Magic Leap – Fiber Scanning Display Follow UP

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Some Newer Information On Fiber Scanning

Through some discussions and further searching I found some more information about Fiber Scanning Displays (FSD) that I wanted to share. If anything, this material further supports the contention that Magic Leap (ML) is not going to have a high resolution FSD anytime soon.

Most of the images available is about fiber scanning for use as a endoscope camera and not as a display device. The images are of things like body parts they really don’t show resolution or the amount of distortion in the image. Furthermore most of the images are from 2008 or older which gives quite a bit of time for improvement. I have found some information that was generated in the 2014 to 2015 time frame that I would like to share.

Ivan Yeoh’s 2015 PhD dissertation

2015-yeoh-laser-projection

In terms of more recent fiber scanning technology, Ivan Yeoh’s name seems to be a common link. Show at left is a laser projected image and the source test pattern from Ivan Yeoh’s 2015 PhD dissertation “Online Self-Calibrating Precision Scanning Fiber Technology with Piezoelectric Self-Sensing“at the University of Washington. It is the best quality image of a test pattern or known image that I have found of a FSD anywhere. The dissertation is about how to use feedback to control the piezoelectric drive of the fiber. While his paper is about the endoscope calibration, he nicely included this laser projected image.

The drive resulted in 180 spirals which would nominally be 360 pixels across at the equator of the image with a 50Hz frame rate. But based on the resolution chart, the effective resolution is about 1/8th of that or only ~40 pixels, but about half of this “loss” is due to resampling a rectilinear image onto the spiral. You should also note that there is considerably more distortion in the center of the image where the fiber will be moving more slowly.

2015-yeoh-endoscope-manual-calibrationYeoh also included some good images at right showing how had previously used a calibration setup to manually calibrate the endoscope before use as it would go out of calibration with various factors including temperature. These are camera images and based on the test charts they are able to resolve about 130 pixels across which is pretty close to the Nyquist sampling rate from a 360 samples across spiral. As expected the center of the image where the fiber is moving the slowest is the most distorted.

While a 360 pixel camera is still very low resolution by today’s standards, it is still 4 to 8 times better than the resolution of the laser projected image. Unfortunately Yeoh was concerned with distortion and does not really address resolution issues in his dissertation. My resolution comments are based on measurements I could make from the images he published and copied above.

Washington Patent Application Filed in 2014

uow-2016-fsd-applicationYeoh is also the lead inventor on the University of Washington patent application US 2016/0324403 filed in 2014 and published in June 2016. At left is Fig. 26 from that application. It is supposed to be of a checkerboard pattern which you may be able to make out. The figure is described as using a “spiral in and spiral out” process where the rather than having a retrace time, they just reverse the process. This applications appears to be related to Yeoh’s dissertation work. Yeoh is shown as living in Fort Lauderdale, FL on the application, near Magic Leap headquarters.   Yeoh is also listed as an inventor on the Magic Leap application US 2016/0328884 “VIRTUAL/AUGMENTED REALITY SYSTEM HAVING DYNAMIC REGION RESOLUTION” that I discuss in my last article. It would appear that Yeoh is or has worked for Magic Leap.

2008 YouTube Video

ideal-versus-actually-spiral-scan

Additionally, I would like to include some images from a 2008 YouTube Video that kmanmx from the Reddit Magic Leap subreddit alerted me to. White this is old, it has a nice picture of the fiber scanning process both as a whole and with close-up image near the start of the spiral process.

For reference on the closeup image I have added the size of a “pixel” for a 250 spiral / 500 pixel image (red square) and what a 1080p pixel (green square) would be if you cropped the circle to a 16:9 aspect ratio. As you hopefully can see the spacing and jitter variations-error in the scan process are several 1080p pixels in size. While this information is from 2008, the more recent evidence above does not show a tremendous improvement in resolution.

Other Issues

So far I have mostly concentrated on the issue of resolution, but there are other serious issues that have to be overcome. What is interesting in the Magic Leap and University of Washington patent literature is the lack of patent activity to address the other issues associated with generating a fiber scanned image. If Magic Leap were serious and had solved these issues with FSD, one would expect to see patent activity in making FSD work at high resolution.

One major issue that may not be apparent to the casual observer is the the controlling/driving the lasers over an extremely large dynamic range. In addition to support the typical 256 (8-bits) per color and supporting overall brightness adjustment based on the ambient light, the speed of the scan varies by a large amount an they must compensate for this or end up with a very bright center where the scan is moving more slowly. When you combine it all together they would seem to need to control the lasers over a greater than 2000:1 dynamic range from a dim pixel at the center to a brightest pixel at the periphery.

Conclusion

Looking at all the evidence there is just nothing there to convince me that Magic Leap is anywhere close to having perfected a FSD to the point that it could be competitive with a conventional display device like LCOS, DLP or Micro-OLED, not less the 50 megapixel resolutions they talk about. Overall, there is reasons to doubt that a electromechanical scan process is going to in the long run compete with an all electronic method.

It very well could be that Magic Leap had hoped that FSD would work and/or it was just a good way to convince investors that they had a technology that would lead to super high resolution in the future. But there is zero evidence that have seriously improved on what the University of Washington has done. They may still be pursuing it as an R&D effort but there is no reason to believe that they will have it in a product anytime soon.

All roads point to ML using either LCOS (per Business Insider of October 2016) or a DLP based what I have heard is in some prototypes. This would mean they will likely have either 720p or 1080p resolution display, or the same as others such as Hololens (which will likely have a 1080p version soon).

The whole FSD is about trying to break through the physical pixel barrier of conventional technologies.  There are various physics (diffraction is becoming a serious issue) and material issues that will likely make it tough to make physical pixels much smaller than 3 micron.

Even if there was a display resolution breakthrough (which I doubt based on the evidence), there are issues as to whether this resolution could make it through the optics. As the resolution improves the optics have to also improve or else they will limit the resolution. This is a factor that particularly concerns me with the waveguide technologies I have seen to date that appear to be at the heart of Magic Leap optics.

Magic Leap – No Fiber Scan Display (FSD)

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Sorry, No Fiber Scan Displays

For those that only want my conclusion, I will cut to the chase. Anyone that believes Magic Leap (ML) is going to have a Laser Fiber Scanned Display (FSD) anytime soon (as in the next decade) is going to be sorely disappointed. FSDs is one of those concepts that sounds like it would work until you look at it carefully. Developed at the University of Washington in the mid to late 2000’s, they were able to generate some very poor quality images in 2009 and as best I can find, nothing better since.

The fundamental problem with this technology is that wiggling a fiber is very hard to control accurately enough to make a quality display. This problem is particularly true when the scanning fiber has to come to near rest in the center of the image. It is next to impossible (and impossible at a rational cost) to have the wiggling fiber tip with finite mass and its own resonate frequency follow a highly accurate and totally repeatable path.

Magic Leap has patents applications related to FSDs showing two different ways to try and increase the resolution, provide they could ever make a decent low resolution display in the first place. Effectively, they have patents that doubled down on FSD, one was the “array of FSDs” which I discussed in the Appendix of my last article that would be insanely expensive and would not work optically in a near eye system and the other doubles down on a single FSD that ML calls “Dynamic Region Resolution” (DRR) which I will discuss below after discussing the FSD basics.

The ML patent applications on the subject of FSD read more like technical fairy tales of what they wished they could do with a bit of technical detail and drawing scattered in to make it sound plausible. But the really tough problems of making it work are never even discussed, no less solutions proposed.

Fiber Scanning Display (FSD) Basics

ml-spiral-scanThe concept of the Fiber Scanning Display (FSD) is simple enough, two piezoelectric vibrators connected to one side of an optical fiber cause the fiber tip follow a spiral path starting from the center and a working its way out. The amplitude of the vibration starts at zero in the center and then gradually increases in amplitue causing the fiber to both speed up and follow a spiral path. At the fiber tip accelerates the tip moves outward radially. The spacing of each orbit is a function of the increase in speed.

ml-fiber-scanning-basic

Red, Green, and Blue (RGB) lasers are combined and coupled into the fiber at the stationary end. As the fiber moves, the lasers turn on an off to create “pixels” that come out the spiraling end of the fiber. At the end a scan, the lasers are turned off and drive is gradually reduced to bring the fiber tip back to the starting point under control (if they just stopped the vibration, it would wiggle uncontrollably).  This retrace period while faster than the scan takes a significant amount of time since it is a mechanical process.

An obvious issue is how well they can control a wiggling optical fiber. As the documents point out, the fiber will want to oscillate based on its resonance frequency that can be stimulated by the piezoelectric vibrators. Still, one would expect that the motion will not be perfectly stable, particularly at the beginning when it is moving slowly and has no momentum.  Then there is the issue as how well it will follow the exactly the same path from frame to frame when the image is supposed to be still.

One major complication I did not see covered in any of the ML or University of Washington (which originated the concept) documents or applications is what it takes to control the laser accurately enough. The fiber speeding up from near zero at its center to maximum speed as the end of the scan. At the center of the spiral the tip moving very slowly (near zero speed). If you turned a laser on for the same amount of time and brightness as the center, pixels would be many times closer together and brighter at the center than the periphery. The ML applications even recognize that increasing the resolution of a single electromechanical  FSD is impossible for all practical purposes.

Remember that they are electromechanically vibrating one end of the fiber to cause the tip to move in a spiral to cover the area of a circle. There is a limit to how fast they can move the fiber, how well they can control it, and the fact that they want fill a wide rectangular area so a lot of the circular area will be cut off.

Looking through everything I could find that was published on the FSD, including Schowengerdt (ML co-founder and Chief Scientist) et al’s SID 2009 paper “1-mm Diameter, Full-color Scanning Fiber Pico Projector” and SID2010 paper, “Near-to-Eye Display using Scanning Fiber Display Engine” only low resolution still images are available and no videos. Below are two images from the SID 2009 paper along with the “Lenna” standard image reproduced in one of them, perhaps sadly, these are best FSD images I could find anywhere. What’s more, there has never been a public demonstration of it producing a video which I believe would show additional temporal and motion problems. 2009-fsd-images2

What you can see in both of the actual FSD images is that the center is much brighter than the periphery. From the Lenna FSD image you can see how distorted the image is particularly in the center (look at Lenna’s eye in the center and the brim of the hat for example). Even the outer parts of the image are pretty distorted. They don’t even have an decent brightness control of the pixels and didn’t even attempt to show color reproduction (requiring extremely precise laser control). Yes the images are old, but there are a series of extremely hard problems outlined above that are likely not solvable which is likely why we have not seen any better pictures of an FSD from ANYONE (ML or others) in the last 7 years.

While ML may have improved upon the earlier University of Washington work, there is obviously nothing they are proud enough to publish, no less a video of it working. It is obvious that non of the released ML videos use a FSD.

Maybe ML had improved it enough to show some promise to get investors to believe it was possible (just speculating). But even if they could perfect the basic FSD, by their own admission in the patent applications, the resolution would be too low to support a high resolution near eye display. They would need to come up with a plausible way to further increase the effective resolution to meet the Magic Leap hype of “50 Mega Pixels.”

“Dynamic Region Resolution (DRR) – 50 Mega Pixels ???

Magic Leap on more than one occasion has talked about the need to 50 Megapixels to support the field of view (FOV) they want with the angular resolution of 1-arcminute/pixel that they say is desirable. Suspending the disbelief that they could even make a good low resolution FSD, they doubled down with what they call “Dynamic Region Resolution” (DRR).

US 2016/0328884 (‘884) “VIRTUAL/AUGMENTED REALITY SYSTEM HAVING DYNAMIC REGION RESOLUTION” shows the concept. This would appear to answer the question of how ML convinced investors that having a 50 megapixel equivalent display could be plausible (but not possible).

ml-variable-scan-thinThe application shows what could be considered to be a “foveated display”, where various area’s of the display varies in image density based on where it will be projected onto the human’s retina. The idea is to have high pixel density where the image will project on the highest resolution part of the eye, the fovea, and that resolution is “wasted” on the parts of the eye that can’t resolve it.

The concept is simple enough as shown in ‘884’s figures 17a and 17b (left). The concept is to track the pupil to see where the eye is looking (indicated by the red “X” in the figures) and then adjust the scan speed, line density, and sequential pixel density based on where the eye is looking. Fig 17a show the pattern for when the eye is looking at the center of the image where they would accelerate more slowly in the center of the scan. In Fig. 17b they show the scanning density to be higher where the eye is looking at some point in the middle of the image. They increase the line density in a ring that covers where the eye is looking.

Starting at the center the fiber tip is always accelerating.  For denser lines they just accelerate less, for less dense areas they accelerate at a higher rate so this sound plausible. The devil is in the details in how the fiber tip behaves as it acceleration rate changes.

Tracking the pupil accurately enough seems very possible with today’s technology. The patent application discusses how wide the band of high resolution needs to be to cover a reasonable range of eye movement from frame to frame which make it sound plausible. Some of the obvious fallacies with this approach include:

  1. Control the a wiggling fiber with enough precision to meet the high resolution and to do it repeatedly from scan to scan. They can’t even do it at low resolution with constant acceleration.
  2. Stability/tracking of the fiber as it increase and decreases its acceleration.
  3. Controlling the laser brightness accurately at both the highest and lowest resolution regions.  This will be particularly tricky as the the fiber increases or decreases it acceleration rate.
  4. The rest of the optics including any lenses and waveguides must support the highest resolution possible for the use to be able to see it. This means that the other optics need to be extremely high precision (and expensive)
What about Focus Planes?

Beyond the above is the need to support ML’s whole focus plane (“poor person’s light field”) concept.  To support focus planes they need 2 to 6 or more images per eye per frame time (say 1/60th of a second). The fiber scanning process is so slow that even producing a single low resolution and highly distorted image in 1/60th is barely possible, no less multiple images per 1/60th of a second to support the plane concept.  So to support the focus plane concept they would need a FSD per focus plane with all its associated lasers and control circuitry; the size and cost to produce would become astronomical.

Conclusion – A Way to Convince the Gullible

The whole FSD appears to me to be a dead end other than to convince the gullible that it is plausible. Even getting a FSD to produce a single low resolution image would take more than one miracle.  The idea of a DRR just doubles down on a concept that cannot produce a decent low resolution image.

The overall impression I get from the ML patent applications is that they were written to impress people (investors?) that didn’t look at the details too carefully. I can see how one can get sucked into the whole DRR concept as the applications gives numbers and graphs that try and show it is plausible; but they ignore the huge issues that they have not figured out.

Magic Leap – Separating Magic and Reality

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The Goal – Explain What is Magic Leap Doing

Magic Leap has a way of talking about what they hope to do someday and not necessarily what they can do anytime soon.  Their patent applications are full of things that are totally impossible or impractical to implement.  I’ve been reading well over a thousand pages of Magic Leap (ML) patents/applications, various articles about the company, watching ML’s “through the optics” videos frame by frame, and then applying my own knowledge of display devices and the technology business to develop a picture of what Magic Leap might produce.

Some warnings in advance

If you want all happiness and butterflies, as well as elephants in your hand and whales jumping in auditoriums, or some tall tale of 50 megapixel displays and of how great it will be someday, you have come to the wrong place.  I’m putting the puzzle together based on the evidence and filling in with what is likely to be possible in both the next few years and for the next decade.

Separating Fact From Fiction

There have been other well meaning evaluations such as “Demystifying Magic Leap: What Is It and How Does It Work?“,  “GPU of the Brain“, and the videos by “Vance Vids” but these tend to start from the point of believing the promotion/marketing surrounding ML and finding support in the patent applications rather than critically evaluating them. Wired Magazine has a series of articles as well as Forbes and others have covered ML, but these have been are personality and business pieces that make no attempt to seriously understand or evaluate the technology.

ml-array-picAmong the biggest fantasies surrounding Magic Leap is the Arrayed Fiber Scanning Displays (FSD); many people think this is real. ML Co-founder and Chief Scientist, Brian Schowengerdt, develop this display concept at the University of Washington based off an innovative endoscope technology and it features prominently in a number of ML assigned patent applications.  There are giant issues in scaling up FSD technology to high resolution and what it would require.

In order to get on with what ML is most likely doing, I have moved to the Appendix why FSDs, light fields, and very complex waveguides are not what Magic Leap is doing. Once you get rid of all the “noise” of the impossible things in the ML patents, you are left with a much better picture of what they are actually could be doing.

What left is enough to make impressive demos and it may be possible to produce at a price that at least some people could afford in the next two years. But ML still has to live by what is possible to manufacture.

Magic Leaps Optical “Magic” – Focus Planes

Fm: Journal of Vision 2009

At the heart all of ML optical related patents is the concept eye vergence-accomodation where the focus of the of the various parts of a 3-D image should agree with their distances or it will cause eye/brain discomfort. For more details about this subject see this information about Stanford’s work in this area and their approach of using quantized (only 2 level) time sequential light fields.

There are some key similarities in that between the Stanford and Magic Leap’s approaches.  They both quantize to a few levels to make them possible to implement and they both present their images time sequentially and they rely on the eye/brain to both fill in between the quantizated levels and integrate a series of time sequential images. Stanford’s approach is decidedly not a “see through” with an Oculus-like setup with two LCD flat panel displays in series where Magic Leap’s goal is to merge the 3-D images with the real world with Mixed Reality (MR).

ml-focus-planesMagic Leap uses the concept of “focus planes” where they conceptually break up a 3-D image into quantized focus planes based on the distance of the virtual image.  While they show 6 virtual planes in Fig. 4 from the ML application above, that is probably what they would like to do but they are doing fewer planes (2 to 4) due to practical concerns.

Magic Leap then renders the parts of an image image into the various planes based on the virtual distance.  The ML optics make it planes appear to the eye like they are focus based their corresponding virtual distance. These planes are optically stacked on top of each other give the final image and they rely on the person’s eye/brain to fill in for the quantization.

Frame Sequential Focus Planes With SLMs

ml-slm-vfe-biocular-systemMagic Leap’s patents/applications show various ways to generate these focus planes, the most fully form concepts use a single display per eye and present the focus planes time sequentially in rapid succession, what ML refers to as “frame-sequential“where there is one focus plane per “frame.”

Both due to the cost and size multiple displays per eye and their associated optics including those to align and overlay them, the only possible way ML could build a product for even a modest volume market is by using frame sequential methods using a a high speed spatial light modulator (SLM) such a DLP, LCOS, or OLED microdisplay.

Waveguides and Focus Planes

Light rays that coming from a far away point that make into the eye are essentially parallel (collimated) and light rays from a near point have a wider set angles.  These differences in angles is what makes them focus differently, but at the same time creates problems for existing waveguide optics, such as what Hololens is using.

The very flat and thin optical structures call “waveguides” will only work with collimated light entering them because of how total light totally internally reflects to stay in the light guide and the the way the diffraction works to make the light exits.  So a simple waveguide would not work for ML.

ml-angle-mirror-deviceSome of ML’s concepts use use one or more beam splitting mirrors type optics rather than waveguides for this reasons. Various ML’s patent applications show using a single large beam splitter or multiple smaller ones (such as at left), but these will be substantially thicker than a typical waveguide.

magic-leap-combiner-cropWhat Magic Leap calls a “Photonics Chip” looks to be at least one layer of diffractive waveguide. There is no evidence of mirror structures, and because it bends the wood in the background (if it were just a simple plate of glass, the wood in the background would not be bent), it appears to be a diffractive optical structure.

Because ML is doing focus planes, they need to have not one, but a stack of waveguides, one per focus plane. The waveguides in ML’s patent applications show collimated light entering the each waveguide in the stack like a normal waveguide, but then the exit diffraction gratings both causes the light to exit also imparts the appropriate focus plane angle to the light.

To be complete, Magic Leap has shown in several patent applications shown some very thick “freeform optics” concepts, but none of this would look anything like the “Photonics Chip” that ML shows.  ML’s patent applications show many different optical configurations and they have demoed a variety of different designs. What we don’t know is if the Photonics Chip they are showing is what they hope to use in the future or if this will be in their first products.

Magic Leaps Fully Formed Designs In Their Recent Patent Applications

Most of Magic Leaps patent applications showing optics have more like fragments of ideas.  There are lots of loose ends and incomplete concepts.

More recently (one publish just last week) there are patent applications assigned to Magic Leap with more “fully formed designs” that look much more like they actually tried to design and/or build them.  Interestingly, these applications don’t include as inventors the founders Rony Abovitz, the CEO, nor even Brian T. Schowengerdt, Chief Scientist, while they may use ideas from those prior “founders patent application.”

While the earlier ML applications mention Spatial Light Modulators (SLMs) using DLP, LCOS, and OLED microdisplays and talk about Variable Focus Element (VFEs) for time sequentially generating focus planes, they don’t really show how to put them together to make anything (a lot is left to the reader).

freeform-opticsPatent Applications 2016/0011419 (left) and 2015/0346495 (below) show straight forward ways to achieve field sequential focus planes using a Spatial Light Modulator (SLM) such as DLP, LCOS or OLED microdisplay.  ml-vfe-with-dlp-003b

As focus plane is created by setting the a variable focus element (VFE) to a one focus point and then generating the image by the SLM. Then the VFE focus is then changed and a second focus plane is displayed by the SLM.  This process can be repeated to generate more focus planes and limited by how fast the SLM can generate image and by level of motion artifact that can be tolerated.

These are clearly among the simplest way to generate focus planes. All that is added over a “conventional” design is the VFE.  When I first heard about Magic Leap many months ago, I heard they were using DLPs with multiple focus depths but a more recent Business Insider is reporting ML is using using Himax LCOS.  Both of these could easily be adapted to support OLED microdisplays.

The big issue I have with the straight forward optical approaches are the optical artifacts I have seen in the videos and the big deal ML makes out of their Photonics Chip (waveguide).  Certainly their first generation might use a more straightforward optical design and then save the Photonics Chip for the next generation.

Magic Leaps Videos Show Evidence of Waveguide Optics

As I wrote last time, there is a lot of evidence from the videos ML has put out that they are using a waveguide at least for the video demos.  The problem is when you bend light in a short distance using diffraction gratings or holograms is that some of the light does not get bent correctly and this shows up colors not lining up (chroma aberrations) as well as what I have come to call the “waveguide glow”.  If at R2D2 below (you may have to click on the image see it clearly) you should see a blue/white glow around R2D2.  I have seen this kind of glow in every diffractive and holographic waveguide I have seen.  I have heard that the glow might be eliminated someday with laser/very narrow bandwidth colors and holographic optics.ml-r2d2-glow2

The point here is that there is a lot of artifact evident that ML was at least using some kind of waveguide in their videos.  This makes it more likely that their final product will also use waveguides and at the same time may have some or all of the same artifacts.

Best Fit Magic Leap Application with Waveguides

If you drew a venn diagram of all existing information, the one patent application that fits best it all is the very recent US 2016/0327789. This is no guarantee that it is what they are doing, but it fits the current evidence best. It combines the a focus plane sequential LCOS SLM (although it shows it could also support DLP but not OLED) with waveguide optics.

The way this works is that for every focus plane there are 3 Waveguides (RED, Green,and Blue) and spatial separate set of LEDs Because the are spatially separate,  they will illuminate the LCOS device at a different angle and after going through the beam splitter the waveguide “injection optics” will cause the light from the different spatially separated LEDs to be aimed at a different waveguide of the same color. Not shown in the figure below is that there is an exit grating that both causes the light to exit the waveguide and imparts an angle to the light based on the focus associated with that give focus plane.  I have coloring in the “a” and “b” spatially separated red paths below (there are similar pairs for blue and green).

With this optical configuration, the LCOS SLM is driven with the image date for a given color for a given focus plane and then the associated color LED for that plane is illuminated.  This process then continues with a different color and/or focus plane until all 6 waveguides for the 3 colors by 2 planes have been illuminated.  ml-slm-beam-splitter-lcos-type-optics-color

The obvious drawbacks with this approach:

  1. There are a lot of layers of waveguide with exit diffraction gratings that the user will be looking through and the number of layers grows by 3 with each added focus plane.  That is a lot of stuff to be looking though and it is bound to degrade the forward view.
  2. There are a lot of optical devices that all the light is passing through and even small errors and leak light builds up.  This can’t be good for the overall optical quality.  These errors have their effect on resolution/blurring, chroma aberrations, and glowing/halo effects.
  3. Being able to switch though all the colors and focus planes fast enough to avoid motion artifacts where the colors and/or the focus planes break up.  Note this issue exist with using any approach that both does field and focus plan sequential.   Obviously this issue becomes worse with more focus planes.

The ‘789 patent show an alternative implementation for using a DLP SLM. Interestingly, this arrangement would not work for OLED Microdisplays as they generate their own illumination so you would not be able to get the spatially separated illumination.

So what are they doing?  

Magic Leap is almost certainly using some form of spatial light modulator with field sequential focus planes (I know I will get push-back form the ML fans that want to believe in the FSD — see the Appendix below); but this is the only way I could see them going to production in the next few years.  Based on the Business Insider information, it could very well be an LCOS device in the production unit.

The the 2015/0346495 with the simple beam splitter would be what I would have choose for a first design provide there is an appropriate variable focus element (VFE) available.  It is by far the simplest design and would seem to have the lowest risk. The downside is that the angled large beamsplitter will make it thicker but I doubt that much more so.   Not only is it lower risk (if the VFE works) but the image quality will likely be better using a simple beam splitter and spherical mirror-combiner than many layers diffractive waveguide.

The 2016/0327789 application touches all the basis based on available information.  The downside is that they need 3 waveguides per focus plane.  So if they are going to say support just 3 focus planes (say infinity, medium, and short focus) they are going to have 9 (3×3) layers waveguides to manufacture and pay for and 9 layers to look through to see the real world.  Even if each layer is extremely good quality, the error will build up in so many layers of optics.  I have heard that the Waveguide in Hololens has been a major yield/cost item and what ML would have to build would seem to be much more complex.   

While Magic Leap certainly could have something totally different, but they can’t be pushing on all fronts at once.  They pretty much have to go with a working SLM technology and get their focus planes time sequentially to build an affordable product.

I’m fond to repeating the 90/90 rule that “it takes 90%  of the effort to get 90% of the way there, then it takes the other 90% to do the last 10%” and someone quipped back, it can also be 90/90/90. The point being is that you can have something that look pretty good and impresses people, but solving the niggling problems, making it manufacturable and cost effective almost always takes more time, effort, and money than people want to think. These problems tend to become multiplicative if you take on too many challenges at the same time.

Comments on Display Technologies

As far as display technologies go each of the spatial light technologies has it pro’s and cons.

  1. LCOS seems to be finding the widest acceptance due to cost.  It is generally lower power in near eye displays than DLP.   The downside is that it has a more modest field rate which could limit the number of focus planes.  It could also be used in any of the 3 prime candidate optical system.  Because the LEDs are separate from the display, they can support essentially any level of brightness.
  2. DLP has the fastest potential field rate which will support more focus planes.  With DLPs they could trade color depth for focus planes.  DLPs will also tend to have higher contrast.  Like LCOS, brightness will not an issue as the LEDs can provide more than enough light.  DLP tends to be higher in cost and power and due to the off axis illumination, tend to have a little bigger optical system that LCOS in near eye applications.
  3. OLED – It has a lot of advantages in that it does not have to sequentially change the color fields, but the current devices still have a slower frame rate than DLP and LCOS can support.  What I don’t know, is how much the field rate is limited by the OLED designs to date versus what they could support if pressed.   The lack of control of the angle of illumination such as used in the ‘789 application.  OLEDs put out rather diffuse with little angle control and this could limit its usefulness with respect to focus plane where you need to  control the angles of light.
  4. FSD Per my other comment and the Appendix below, don’t hold your breath waiting for FSDs.
Image Quality Concerns

I would be very concerned about Magic Leap’s image quality and resolution beyond gaming applications. Forget all those magazine writers and bloggers getting all geeked out over a demo with a new toy, at some point reality must set in.

Looking at what Magic Leap is doing and what I have seen in the videos about the effective resolution and image quality it is going to be low compared to what you get even on a larger cell phone.  They are taking a display device that could produce a good image (either 720p or maybe 1080p) under normal/simple optics and putting it through a torture test of optical waveguides and whatever optics used to generate their focus planes at a rational cost; something has to give.

I fully expect to see a significant resolution loss no matter what they do plus chroma aberrations, and waveguide halos provide they use waveguides.  Another big issue for me will be the “real world view” through whatever it takes to create the focus planes and how will it effect you say seeing you TV or computer monitor through the combiner/waveguide optics.

I would also be concerned about field sequential artifacts and focus plane sequential artifacts.  Perhaps these are why there are so many double images in the videos.

Not to be all doom and gloom.  Based on casual comments from people that have seen it and the fact that some really smart people invested in Magic Leap,  it must provide an interesting experience and image quality is not everything for many applications. It certainly could be fun to play with at least for a while. After all, Oculus rift has a big following and its angular resolution is so bad that they cover up by blurring and it has optical problems like “god rays.”

I’m more trying to level out the expectations.   I expect it to be a long way from replacing your computer monitor, as one reporter suggested, or even your cell phone, at least for a very long time. Remember that this has so much stuff in that in addition to the head worn optics and display you are going to have a cable down to the processor and battery pack (a subject I have only barely touched on above).

Yes, Yes, I know Magic Leap has a lot of smart people and a lot of money (and you could say the same for Hololens), but sometime the problem is bigger than all the smart people and money can solve.

Appendix: 

The Big Things Magic Leap is NOT Going To Make in Production Anytime Soon

The first step in understand Magic Leap is to remove all the clutter/noise that ML has generated.  As my father use to often say, there are to ways to hide information, you can remove it from view or your can bury it.” Below is a list of the big things that are discussed by ML themselves and/or in their patents that are either infeasible or impossible any time soon.

It would take a long article on each of these to give all the reasons why they are not happening, but hopefully the comments below will at least outline the why:

ml-array-pic

A) Laser Fiber Scanning Display (FSD) 

A number of people of picked up on this particularly because the co-founder and Chief Scientist, Brian Schowengerdt, developed this at the University of Washington.  The FSD comes in two “flavors” the low resolution single FSD and the Arrayed FSD

1) First, you pretty limited on the resolution of a single mechanically scanning fiber (even more so than Mirror scanners). You can only make them spiral so fast and they have their own inherent resonance. They make an imperfectly space circular spiral that you then have to map a rectangular grid of pixels onto. You can only move the fiber so fast and you can trade frame rate for resolution a bit but you can’t just make the fiber move faster with good control and scale up the resolution. So maybe you get 600 spirals but it only yields maybe 300 x 300 effective pixels in a square.

2) When you array them you then have to overlap the spirals quite a bit. According to ML patent US 9,389,424 it will take about 72 fibers scanner to made a 2560×2048 array (about 284×284 effective pixels per fiber scanner) at 72 Hz.

3) Lets say we only want 1920×1080 which is where the better microdisplays are today or about 1/2.5 of 72 fiber scanners or about 28 of them. This means we need 28 x 3 (Red, Green, Blue) = 84 lasers. A near eye display typical outputs between 0.2 and 1 lumen of light and you divide this then by 28. So you need a very large number really tiny lasers that nobody I know of makes (or may even know how to make). You have to have individual very fast switching lasers so you can control them totally independently and at very high speed (on-off in the time of a “spiral pixel”).

4) So now you need to convince somebody to spend hundreds of millions of dollars in R&D to develop very small and very inexpensive direct green (particularly) lasers (those cheap green lasers you find in laser pointers won’t work because they switch WAY to slow and are very unstable). Then after they spend all that R&D money they have to then sell them to you very cheap.

5) Laser Combining into each fiber. You then have the other nasty problem of getting the light from 3 lasers into a single fiber; it can be done with dichroic mirrors and the like but it has to be VERY precise or you miss the fiber. To give you some idea of the “combining” process you might want to look at my article on how Sony combined 5 lasers (2 Red, 2 Green, and 1 Blue for brightness) for a laser mirror scanning projector http://www.kguttag.com/2015/07/13/celluonsonymicrovision-optical-path/. Only now you don’t do this just once but 28 times. This problem is not impossible but requires precision and precision cost money. Maybe if you put enough R&D money into it you can make it on a single substrate.  BTW, It looks to me that in the photo you see of Magic Leap prototype (https://www.wired.com/wp-content/uploads/2016/04/ff_magic_leap-eric_browy-929×697.jpg) it looks like they didn’t bother combining the lasers into single fibers.

6) Next to get the light injected into a waveguide you need to collimate the arrays of cone shaped light rays. I don’t know of any way, even with holographic optics that you can Collimate this light because you have overlapping rays of light going in different directions.  You can’t collimate the individual cones of light rays or there is not way to get them to overlap to make a single image without gaps in it. I have been looking through the ML patent applications an they never seem to say how they will get this array of FSDs injected into a waveguide. You might be able to build this in a lab for one that is horribly inefficient by diffusing the light first but it would be horribly inefficient.

7) Now you have the issue of how are you going to support multiple focus planes. 72Hz is not fast enough to do it Field Sequentially so you have to put in either parallel ones so multiply by the number of focus planes. The question at this point is how much more than a Tesla Model S (starting at $66K) will it cost in production.

I think this is a big ask when you can buy an LCOS engine at 720p (and probably soon 1080p) for at about $35 per eye. The theoretical FSD advantage is that it might be able to be scaled it up to higher resolutions but you are several miracles away from that today.

ml-wavefrontB) Light Fields, Light Waves, etc.

 There is no way to support any decent resolution with Light Fields that is going to fit on anyone’s head.  It takes about 50 to 100 times the simultaneous image information to support the same resolution with a light field.  Not only can’t you afford to display all the information to support good resolution, it would take and insane level of computer processing. What ML is doing is a “shortcut” of multiple focus planes which is at least possible.  The “light wave display” is insane-squared, it requires the array of fibers to be in perfect sync among other issues.

ml-multi-displayC) Multiple Displays Driving the Waveguides

ML patents show passive waveguides with multiple displays (fiber scanning or conventional) driving them. It quickly becomes cost prohibitive to support multiple displays (2 to 6 as the patents show) all with the resolution required.

ml-vfe-compensation4) Variable Focus Optics on either side of the Waveguides

Several of their figures show electrically controlled variable focus elements (VFE) optics on either side of the waveguides with one set changing the focus of a frame sequential image plane compensating while a second set of VFE compensates so the  “real world” view remains in focus. There is zero probability of this working without horribly distorting the real world view.

What Magic Leap Is Highly Unlikely to Produce

multiplane-waveguideActive Switching Waveguides – ML patents applications show many variations they drawn attention from other articles. The complexity of making them and the resultant cost is one big issue.  There would likely be serious the degradation to the view all the layers and optical structures through to the real world.  Then you have the cost both in terms of displays and optics to get images routed to the various planes of the waveguide.  ML’s patent applications don’t really say how the switching would work other than saying they might use liquid crystal or lithium niobate but nothing so show they have really thought it through.   I put this in the “unlikely” category because companies such as DigiLens have built switchable Bragg Gratings.

Magic Leap Video – Optical Issues and a Resolution Estimate

ml-new-morning-upper-lower-crops-thumbnail

As per my previous post Magic Leaps display technology what Magic Leap is using in their YouTube through the lens demos may or may not be what they will use in the final product. I’m making an assessment of their publicly available videos and patents.  There is also the possibility that Magic Leap is putting out deliberately misleading videos to throw off competitors and whomever else is watching.

Optical Issues: Blurry, Chroma Aberrations, and Double Images

I have been looking at a lot of still frames from the ML’s “A New Morning” video that according the ML is “Shot directly through Magic Leap technology on April 8, 2016 without use of special effects or compositing.”  I chose this video because it has features like text and lines (known shapes) that can better reveal issues with the optics. The overall impression looking at the images they are all somewhat blurry with a number of other optical issues.

Blurry

resolution-01b-cropThe crop of a frame at 0:58 on the left shows details that include real world stitching of a desk organizer with 3 red 1080p pixel dots added on top of two of the stitches. The two insets show 4X pixel replicated blow-ups so you can see the details.

Looking at the “real world” stitches, the camera has enough resolution to capture the cross in the “t” in “Summit” and the center of the “a” in Miura” if they were not blurred out by the optics.

Chroma Abberations

If you look at the letter “a” in the top box, you should notice the blue blur on the right side that extends out a number of 1080p pixels.  These chroma aberrations are noticeable throughout the the frame, particularly at the edges of white objects.  These aberrations indicate that the R, G, and B colors are not all focused and add to the blurring.

The next question is whether the chroma aberration is cause by the camera or the ML optics. With common camera optics, chroma aberrations get worst the further you get away from the center.

resolution-01b-chroma-cropIn the picture on the left, taken from the same 0:53 frame the name “Hillary” (no relation to the former presidential candidate) is near the top of the screen and “Wielicki” is near the middle. Clearly the the name “Wielicki” has significantly worse chroma aberration even though it is near the center of the image. This tends to rule out the camera as the source of the aberration as it is getting worse from top (outside) to the center. Based on this fact, it appears that the chroma aberrations are caused by the ML optics.

resolution-01b-full-frameFor those that want to see the whole frame, click on the image a the right.

Double Images

Consistently during the entire video there are double images the further down and further left you look at the image. These are different from the frame update double images from last time. as they appear when there is no movement and they are dependent on location.

Below I have gone through a sequence of different frames to capture similar content in the upper left, center, and right (UL, UC, UR), as well as the Middle (M), and Lower (L) left, center, and right and put them side by side. I did the best I could to get the best image I could find in each region (using different content for the lower left).  I have done this over a number of frame checking for focus issues and motion blur and the results are the same, the double image is always worse in the bottom and far left.ml-new-morning-upper-lower-crops2

The issue seen are not focusing nor movement problems. Particularly notice, in the lower left (LL) image how the “D” is a double image is displaced slightly higher and to the right. A focus problem would blur it concentrically and not in a single direction.

Usually double images of the the same size are result of reflections off of flat plates.  Reflections off a curved surface, such as a camera lens pr curved mirror would magnify or reduce the reflection.   So this suggests that the problem has something to do with flat or nearly plates which could be a flat waveguide or a flat tilted plate combiner.

The fact that the image gets worse the further down and left would suggest (this is somewhat speculative) that the image in coming from near the top right corner.   Generally an image will degrade more the further it has to go through a waveguide or other optics.

One more thing to notice particularly on the images on the three on the right side are “jaggies” in the horizontal line below the text.

What, there are Jaggies? A clue to the resolution which appears to be about 720p

Something I was not expecting to see were the stair step effect of a diagonally drawn line, particularly through the blurry optics.  Almost all modern graphics rendering does “antialiasing”/smooth edge rendering with gray scale values that smooth out these steps, and after the losses due to the optics and camera I was not expecting to see any jaggies.  There are no visible jaggies for all the lines and text in the image with the notable exception for the lines under the text of “TODAY” and “YESTERDAY” associated with the notification icons.

In watching the video playing it is hard to miss these lines as the jaggies move about drawing your eye to them.  The jaggies’ movement it also a clue that they are moving the drawn image as the camera moves slightly.

Below I have taken one of those lines with jaggies and then below it I have simulated the effect in Photoshop with 4 lines below it.  The results have been magnified by 2X and you may want to click in the image below to see the detail.  One thing you may notice in the ML Video line is that in addition to the jaggies, it appears to have thick spots in it.  These thick spots between jaggies are caused by the line being both at an angle and with slight perspective distortion which causes the top and bottom of a wider than one pixel thick line be rendered at slightly different angles which causes the jaggies to occur in different places on the top and bottom and results in the thick sections.  In the ML Video line there are 3 steps on the top (pointed to by the green tick marks) and 4 on the bottom (indicated by red tick marks).
resolution-jaggies-02

Below the red line, I simulated the effect using Photoshop on the 1080p image and copied the color of background to be the background for the simulation.  I started with a thin rectangle that was 4 pixels high and then scaled it by making it very slightly trapezoidal (about 1 degree difference between the top and bottom edge) and then rotated it to the same angle as the line in the video, using “nearest neighbor” (no smoothing/antialiasing) scaling; this produced the 3rd line “Rendered w/ jaggies”.   I then applied a Gaussian with a 2.0 pixel radius to simulate the blur from the optics to produce the “2.0 Gaussian of Jaggies” line that matches the effect seen in the ML video. I did not bother with simulating the chroma aberrations (the color separation above and below the white line) that would further soften/blur the image.

Looking at result you will see the thick and thin spots just like the ML video.  But note there are about 7 steps (at different places) on the top and bottom.  Since the angle of my simulated line and the angle of the line in the ML Video are the same and making the reasonable assumption that the jaggies in the video are 1 pixel high, the resolution should differ by the ratio of the jaggies or about 4/7 (ratio of the ML versus the 1080p jaggies).

Taking 1080 (lines) times 4/7 give about 617 lines which what you would expect right if they slightly cropped a 720p image.  This method while very rough and assumes they have not severely cropped the image with the camera (to make themselves look bad).

For completeness to show the difference with what would happen if the light was rendered with antialiasing, I produced the “AA rendered” version and then use did the same Gaussian blur on it. This results, similar to all the other lines in the video where there are no detectable jaggies nor any changing in the apparent thickness of the line.

OK, I can here people saying, “But the Magazine Writers Said It Looked “Good/Great”

I have often said that for a video demo, “If I can control the product or control the demo content, I choose controlling the content.” This translates to “choose demo content that looks good on your product and eliminate content that will expose its weaknesses.”

If you show videos with a lot of flashy graphics and action with no need to look for detail, with smooth rendering, only imaging experts might notice that the resolution is low and/or there are issues with the optics.  If you put up text, use a larger font so that it is easily readable, most people will think you have high resolution sufficient for reading documents; in the demo you are not giving them a page of high resolution text to read if you don’t have high resolution.

I have been working with graphics and display devices for about 38 years and see a LOT of demos.  Take it from me, the vast majority of people can’t tell anything about resolution, but almost everyone thinks they can.  For this reason, I highly discount report from non display experts that have a chance to seriously evaluate a display. Even an imaging experts can be fooled by a quick well done demo or a direct or indirect financial motive.

Now, I have not seen what the article writers and the people that invested money (and their experts) have seen.  But what I hopefully have prove to you is that the what Magic Leap has shown in their YouTube videos is of pretty poor image quality by today’s standards.

Magic Leap Focus Effects
ml-out-of-focus

0:41 Out of Focus

ml-in-of-focus

0:47 Becoming In Focus

ml-in2-of-focus

1:00 Sharpest Focus

ml-back-out-of-focus

1:05 Back Out Of Focus

Magic Leap makes a big point of the importance of “vergence,” which means that the apparent focus agrees with the apparent distance in 3-D space. This is the key difference between Magic Leap and say Microsoft’s Hololens.

With only one lens/eye you can’t tell the 3-D stereo depth so they have to rely on how the camera focuses.  You will need to click on the thumbnails above to see the the focus effects in the various still captures.

They demonstrate the focus effects with “Climbing Everest” sequence in the video.  ML was nice enough to put some Post-It (TM) type tabs curled up in the foreground (in particular watch the yellow smiley face in the lower left) and a water bottle and desk organizer (with small stitches in the background.

Toward the end of the sequence (click on the 1:05 still) you can see the Mount Everest information which is at an angle relative to the camera is highly out of focus on the left hand side and gets better the right hand side, while the “Notices” information which appears to be further away is comparatively is in-focus. Also notice how the stitches in the desk organizer in the real world and which appear to be roughly the same angle as the Everest Information goes from out of focus on the left to more in-focus on the right agreeing with what is seen in the projected image.

This focus rake appears to be conclusive proof that that there is focus depth in the optical system in this video.  Just to be complete, it would be possible to the fake effect just for the video is by blurring the image by the computer synchronously with the focus rake.  But I doubt they “cheated” in this way as outsiders have reported seeing the focusing effect in  live demos.

In the 1:05 frame capture the “15,000 ft” in the lower left is both out of focus and has a double image which makes it hard to tell which are deliberate/controllable focusing effects and which are just double images due to poor optics. Due to the staging/setup, the worst part of the optics matches what should be the most out of focus part of the image.  This could be a coincidence or they may have staged it that way.

Seeing the Real World Through Display

Overall, seeing the real world through the display looks very good and without significant distortion.  It didn’t get any hints as to the waveguide/combiner structure.   It would be interesting to see what say a computer monitor would look like through the display or other light source shining through it.

The the lighting in the video is very dark; the white walls are dark gray due to a lack of light except where some lamps act as spotlights on them.  The furniture and most of the other things on the desk are black or dark (I guess the future is going to be dark and have a lot of black furniture and other things in it). This setup helps the generated graphics stand out. In a normally lit room with white wall, the graphics will have to be a lot brighter to stand out and there are limits to how much you can crank up the brightness without hurting people’s eyes or there will have to be a darkening shades as seen with Hololens.

Conclusion

The resolution appears to be about 720p and the optics are not up to showing that resolution.  I have been quite  of the display quality because it really is not good. There are image problems that are many pixels wide.

On the plus side, they are able to demonstrate the instantaneous depth of field with their optical solution and the view of the real world looks good so far as they have shown.  There may be issues with the see-through viewing that are not visible in these videos in a fairly dark environment.

I also wonder how the resolution translates into the FOV versus angular resolution, and how they will ever support multiple simultaneous focus planes.  If you discount a total miracle from their fiber scanned display happening anytime soon (to be covered next time), 720p to at most 1080p is about all that is affordable in a microdisplay today, particularly when you need one for each eye, in any production technology (LCOS, DLP, or Micro-OLED) that will be appropriate for a light guide.  And this is before you consider that to support multiple simultaneous focus planes, they will need multiple displays or a higher resolution display that they cut down. To me as a technical person who studied displays for about 18 years, this is a huge ask.

Certainly Magic Leap must have shown something that impressed some very big name investors, to invest $1.4B.  Hopefully it is something Magic Leap has not shown yet.

Next Time: Magic Leap’s Fiber Scanned Display

I have been studying the much promoted Magic Leap Fiber Scan Display (FSD).  It turns out there patents suggest two ways of using this technology:

  1. A more conventional display that can be used in combination with a waveguide with multiple focus layers.
  2. To directly generate a light fields from an array of FSDs

I plan to discuss the issues with both approaches next time.  To say the least, I’m high doubtful that either method is going to be in volume production any time soon and I will try and outline my reasons why.

Asides: Cracking the Code
Enigma

I was wondering whether the jaggies were left in as an “image generation joke” for insiders or just sloppy rendering. They are a big clue as to the native resolution of the display device that came through the optical blur and the camera’s resolving power.

It is a little like when the British were breaking of the Enigma code in WWII. A big help in breaking Enigma was sloppy transmitting operators giving them what they called “cribs” or predictable words or phrases. On a further aside, Bletchley Park where the cracked the Enigma Code is near Bedford England where I worked with and occasionally lived for over an 16 year period. Bletchley Park is a great place to visit if you are interested in computer history (there is also a computer museum at the same location).  BTW, the movie the “The Imitation Game” is an enjoyable movie but lousy history.

Solving the Display Puzzles

Also, I am not claiming to be infallible in trying to puzzle out what is going on with the various technologies. I have change my mind/interpretation of what I am seeing in the videos a number of times and some of my current conclusions may have alternative explanations. I definitely appreciate readers offering their alternative explanations and I will try and see if I think they fit the facts better.

Magic Leap’s work is particularly interesting because they have made such a big claims, raised so much money, are doing something different, and have released tantalizingly little solid information.  It also seems that a good number of people are expecting Magic Leap to do a lot more with their product than may be feasible at volume price point or even possible at any cost, at least for a number of years.

Magic Leap – The Display Technology Used in their Videos

ml-new-morning-text-images-pan-left

So, what display technology is Magic Leap (ML) using, at least in their posted videos?   I believe the videos rule out a number of the possible display devices, and by a process of elimination it leaves only one likely technology. Hint: it is NOT laser fiber scanning prominently shown number of ML patents and article about ML.

Qualifiers

Magic Leap, could be posting deliberately misleading videos that show technology and/or deliberately bad videos to throw off people analyzing them; but I doubt it. It is certainly possible that the display technology shown in the videos is a prototype that uses different technology from what they are going to use in their products.   I am hearing that ML has a number of different levels of systems.  So what is being shown in the videos may or may not what they go to production with.

A “Smoking Gun Frame” 

So with all the qualifiers out of the way, below is a frame capture from Magic Leaps “A New Morning” while they are panning the headset and camera. The panning actions cause temporal (time based) frame shutter artifact in the form of partial ghost images as a result of the camera and the display running asynchronously and/or different frame rates. This one frame along with other artifacts you don’t see when playing the video, tells a lot about the display technology used to generate the image.

ml-new-morning-text-images-pan-leftIf you look at the left red oval you will see at the green arrow a double/ghost image starting and continuing below that point.  This is where the camera caught the display in its display update process. Also if you look at the right side of the image you will notice that the lower 3 circular icons (in the red oval) have double images where the top one does not (the 2nd to the top has a faint ghost as it is at the top of the field transition). By comparison, there is not a double image of the real world’s lamp arm (see center red oval) verifying that the roll bar is from the ML image generation.

ml-new-morning-text-whole-frameUpdate 2016-11-10: I have upload for those that would want to look at it.   Click on the thumbnail at left to see the whole 1920×1080 frame capture (I left the highlighting ovals that I overlaid).

Update 2016-11-14 I found a better “smoking gun” frame below at 1:23 in the video.  In this frame you can see the transition from one frame to the next.  In playing the video the frame transition slowly moves up from frame to frame indicating that they are asynchronous but at almost the same frame rate (or an integer multiple thereof like 1/60 or 1/30th)

ml-smoking-gun-002

 In addition to the “Smoking Gun Frame” above, I have looked at the “A New Morning Video” as well the “ILMxLAB and ‘Lost Droids’ Mixed Reality Test” and the early “Magic Leap Demo” that are stated to be “Shot directly through Magic Leap technology . . . without use of special effects or compositing.”through the optics.”   I was looking for any other artifacts that would be indicative of the various possible technologies

Display Technologies it Can’t Be

Based on the image above and other video evidence, I think it save to rule out the following display technologies:

  1. Laser Fiber Scanning Display – either a single or multiple  fiber scanning display as shown in Magic Leaps patents and articles (and for which their CTO is famous for working on prior to joining ML).  A fiber scan display scans in a spiral (or if they are arrayed an array of spirals) with a “retrace/blanking” time to get back to the starting point.  This blanking would show up as diagonal black line(s) and/or flicker in the video (sort of like an old CRT would show up with a horizontal black retrace line).  Also, if it is laser fiber scanning, I would expect to see evidence of laser speckle which is not there. Laser speckle will come through even if the image is out of focus.  There is nothing to suggest in this image and its video that there is a scanning process with blanking or that lasers are being used at all.  Through my study of Laser Beam Scanning (and I am old enough to have photographed CRTs) there is nothing in the still frame nor videos that is indicative of a scanning processes that has a retrace.
  2. Field Sequential DLP or LCOS – There is absolutely no field sequential color rolling, flashing, or flickering in the video or in any still captures I have made. Field sequential displays, display only one color at a time very rapidly. When these rapid color field changes beat against the camera’s scanning/shutter process.  This will show up as color variances and/or flicker and not as a simple double image. This is particularly important because it has been reported that Himax which makes field sequential LCOS devices, is making projector engines for Magic Leap. So either they are not using Himax or they are changing technology for the actual product.  I have seen many years of DLP and LCOS displays both live and through many types of video and still cameras and I see nothing that suggest field sequential color is being used.
  3. Laser Beam Scanning with a mirror – As with CRTs and fiber scanning, there has to be a blanking/retrace period between frames will show up in the videos as roll bar (dark and/or light) and it would roll/move over time.  I’m including this just to be complete as this was never suggested anywhere with respect to ML.
UPDATE Nov 17, 2016

Based on other evidence that as recently come in, even though I have not found video evidence of Field Sequential Color artifacts in any of the Magic Leap Videos, I’m more open to thinking that it could be LCOS or (less likely) DLP and maybe the camera sensor is doing more to average out the color fields than other cameras I have used in the past.  

Display Technologies That it Could Be 

Below are a list of possible technologies that could generate video images consistent with what has been shown by Magic Leap to date including the still frame above:

  1. Mico-OLED (about 10 known companies) – Very small OLEDs on silicon or similar substrates. As list of the some of the known makers is given here at OLED-info (Epson has recently joined this list and I would bet that Samsung and others are working on them internally). Micro-OLEDs both A) are small enough toinject an image into a waveguide for a small headset and B) has the the display characteristics that behave the way the image in the video is behaving.
  2. Transmissive Color Filter HTPS (Epson) – While Epson was making transmissive color filter HTPS devices, their most recent headset has switch to a Micro-OLED panel suggesting they themselves are moving away.  Additionally while Meta first generation used Epson’s HTPS, they moved away to a large OLED (with a very large spherical reflective combiner).  This technology is challenged in going to high resolution and small size.
  3. Transmissive Color Filter LCOS (Kopin) – is the only company making Color Filter Transmissive LCOS but they have not been that active as of last as a component supplier and they have serious issues with a roadmap to higher resolution and size.
  4. Color Filter reflective LCOS– I’m putting this in here more for completeness as it is less likely.  While in theory it could produce the images, it generally has lower contrast (which would translate into lack of transparency and a milkiness to the image) and color saturation.   This would fit with Himax as a supplier as they have color filter LCOS devices.
  5. Large Panel LCD or OLED – This would suggest a large headset that is doing something similar to the Meta 2.   Would tend to rule this out because it would go against everything else Magic Leap shows in their patents and what they have said publicly.   It’s just that it could have generated the image in the video.
And the “Winner” is I believe . . . Micro-OLED (see update above) 

By a process of elimination including getting rid of the “possible but unlikely” ones from above, it strongly points to it being Micro-OLED display device. Let me say, I have no personal reason to favor it being Micro-OLED, one could argue it might be to my advantage based on my experience for it to be LCOS if anything.

Before I started any serious analysis, I didn’t have an opinion. I started out doubtful that it was field sequential or and scanning (fiber/beam) devices due to the lack of any indicative artifacts in the video, but it was the “smoking gun frame” that convince me that that if the camera was catching temporal artifacts, it should have been catching the other artifact.

I’m basing this conclusions on the facts as I see them.  Period, full stop.   I would be happy to discuss this conclusion (if asked rationally) in the comments section.

Disclosure . . . I Just Bought Some Stock Based on My Conclusion and My Reasoning for Doing So

The last time I played this game of “what’s inside” I was the first to identify that a Himax LCOS panel was inside Google Glass which resulted in their market cap going up almost $100M in a couple of hours.  I had zero shares of Hixmax when this happened, my technical conclusion now as it was then was based on what I saw.

Unlike my call on Himax in Google Glass I have no idea which company make the device Magic Leap appears to using nor if Magic Leap will change technologies for their production device.  I have zero inside information and am basing this entirely on the information I have given above (you have been warned).   Not only is the information public, but it is based on videos that are many months old.

I  looked at companie on the OLED Microdisplay List by www.oled-info.com (who has followed OLED for a long time).  It turned out all the companies were either part of a very large company or were private companies, except for one, namely eMagin.

I have know of eMagin since 1998 and they have been around since 1993.  They essentially mirror Microvision doing Laser Beam Scanning and was also founded in 1993, a time where you could go public without revenue.  eMagin has spent/loss a lot of shareholder money and is worth about 1/100th from their peak in March 2000.

I have NOT done any serious technical, due diligence, or other stock analysis of eMagin and I am not a stock expert. 

I’m NOT saying that eMagine is in Magic Leap. I’m NOT saying that Micro-OLED is necessarily better than any other technology.  All I am saying is that I think that someone’s Micro-OLED technology is being using the Magic Leap prototype and that Magic Leap is such hotly followed company that it might (or might not) affect the stock price of companies making Micro-OLEDs..

So, unlike the Google Glass and Himax case above, I decided to place a small “stock bet” (for me) on ability to identify the technology (but not the company) by buying some eMagin stock  on the open market at $2.40 this morning, 2016-11-09 (symbol EMAN). I’m just putting my money where my mouth is so to speak (and NOT, once again, stock advice) and playing a hunch.  I’m just making a full disclosure in letting you know what I have done.

My Plans for Next Time

I have some other significant conclusions I have drawn from looking at Magic Leap’s video about the waveguide/display technology that I plan to show and discuss next time.

Magic Leap “A Riddle Wrapped in an Enigma”

ml-combiners-from-us-20150241705

magic-leap-combiner-cropSo what is Magic Leap doing?  That is the $1.4 billion dollar question. I have been studying their patents as well as videos and articles about them and frankly a lot of it does not add up.   The “Hype Factor” is clearly off the chart with major and high tech news/video outlets covering them with a majors marketing machine spending part of the $1.4B, yet no device has been shown publicly, only a few “through the Magic Leap” online videos (6 months ago and 1 year ago).   Usually something this much over-hyped ends up like Segway (I’m not the first to make the Segway comparison to Magic Leap) or more recently Google Glass.

Magic Leap appears to be moving on many different technological fronts at once (high resolution fiber scanning display technology, multi-focus- combiner/light fields, and mega-processing to support the image processing required) which almost always is a losing strategy even for a large company no less a startup, albeit a well funded one. What’s more, and the primary subject of this article, they appear to be moving on many different fronts/technologies with respect to the multi-focus-combiner.

Based on the image above from Wired in April 2016 and other articles talking about a “photonic chip,” a marketing name for their combiner not used in any of their patent applications that I could find.   By definition, a photonic device would have some optical property that is altered electronically, but based on other comments made by Magic Leap and looking at the patents, the so called “chip” is just as likely a totally passive device.

ml-scanned-fiber-applicationIt is also well known that Magic Leap is working on piezo scanned laser fiber displays, a display technology initially developed by Magic Leap’s CTO while at the University of Washington (click left for a bigger image). Note that is projects a spiraling cone of light.

A single scanning display is relatively low resolution and so to achieve Magic Leaps resolution goals will require arrays of these scanning fibers as outlined in their US Application 2015/0268415.

Magic Leap is moving in so many different directions at the same time. I plan on covering the scanning fiber display in more detail much more detail in the near future.   

Background – Nvidia and Stanford Light Fields

A key concept running through everything about Magic Leap it is that their combiner supports at least multiple focus depths at the same time.   The term “Light Fields” is often used in connection with Magic Leap, but what they are doing is not classic light fields such as Nvidia has demonstrated (very good article and video is here).   Or even what Stanford’s Gordon Wetzstein work talks about with compressive light field displays (example here) and several of his YouTube videos, in particular this one that discusses light fields and the compressive display.   (More on this background at the end). 

A key think to understand about “light fields” and Magic Leaps multi-focus-planes is that they are based on controlling the angles of the rays of light as it controls the focus distance.   The rays of light that will make it through the eye’s pupil from a point on far away objects come in nearly parallel, whereas the rays from a nearby point have a wider range of angles.

Magic Leap Patents

Magic Leaps patents show a mix of related and very different types of waveguide combiners.   Most in-line with what Magic Leap talks about in the press and videos are the ones that include multi-plane waveguides and scanned laser fiber displays.   These include US patent applications US20150241705 (‘705) and the 490 page US20160026253 (‘253).  I have clipped out some of the key figures from each below (click on the images to see larger images).

ml-combiners-from-us-20150241705Fig. 8 from the ‘705 patent uses a multi-layer electrically switched diffraction grating waveguide (but they don’t say what technology they expect to use to cause the switching). In addition to switching each diffraction grating makes the image focus differently as shown in Fig. 9.  While this “fits” with the “photonic chip” language by Magic Leap, I’m less inclined to believe this is what Magic Leap is doing based on the evidence to date (although Digilens has developed switchable SBGs in their waveguides).

Fig. 6 likely comes closer to what Magic Leap seems to be working on, at least in the long term. In this case there is one or more laser scanning fiber displays for each layer of the diffraction grating (similar to Fig. 8 but passive/fixed). The gratings layers in this setup are passive and based on which display is “on” chooses the grating layer and thus chooses the focus.  Also note the ” collimation element 6” between the scanning fibers 602a-e and the waveguide 122. They take the cone of rays from the spiral scanning fiber and turns them into an array of parallel (collimated) rays. Below shows a prototype from the June 2016 “Wired” article with two each of red, green, blue fibers per eye (6 total)ml-combiners-from-us-20150346495which would support two simultaneous focus points (in future articles I plan on going into more about the scanning fiber displays).

wired-photo-croppedAbove I have put together a series of figures from Magic Leap’s US patent application 2015/0346495.  Most of these are difference approaches to accomplish essentially the same effect, namely to create 2 or more images in layers that appear to be in focus at different distances.  In some approaches they will generate the various focused images time sequentially and rely on the eye’s persistence of vision to fuse them (the Stanford Compressive Display works sequentially).  You may note that some of the combiner technologies shown above are not that flat including what is known as  “free form optics” (Fig. 22G above) that would be compatible with a panel (DLP, LCOS, or Micro-OLED display).

And Now for something completely different

ml-495-application

To the left patent application 2015/0346495 that shows a very different optical arrangement with a totally different set of inventors from the prior patents.   This device supports multiple focus effects via a Variable Focus Element (VFE).   What they do is generate a series of images sequentially and change the focus between images and use the persistence of the human visual system to fuse the various focused images.

This is a totally different approach to achieve the same effect.   It does requires a very fast image generating device which would tend to favor DLP and OLED over say LCOS as the display device.   I have questions as to how well the time sequential layers will work with a moving image and would there be temporal breakup-effect.

There are also a number of patents with totally different optical engines and totally different inventors (and not principles of Magic Leap) with free-form (very thick/non-flat) optics  20160011419 and 20160154245 which would fit with using an LCOS (or DLP) panel instead of the laser fiber scanning display.

I have heard from more than one source that at least some early prototypes by Magic Leap used DLPs.  This would suggest some form of time sequential focusing.

Problems I See with the “Photonic Chip” Magic Leap Showed in the June 2016 Wired picture

hololens-combiner-002-sm“Edge injection” waveguide – There needs to be an area to inject the light.  All the waveguide structures in Magic Leaps patents show use “side/edge” injection of the image.  Compare to the Microsoft’s Hololens (at right)which injects  the image
light in the face (highlighted with the green dots).   With a edge injected waveguide, the waveguide would need to be thicker for even a single layer, no less the multiple layers with multiple focus distances that Magic Leap is requires.

lumusLumus (at left) has series of exit prisms similar to a single layer of the Magic Leap ‘495 application Figs. 5H, 6A, 8A, and 10.  Lumus does edge injection but at roughly a 45 degree angle (see circled edge) which gives more area to inject the image and gets the light started at an angle sufficient for Total Internal Reflection (TIR).  There is nothing like this in the Magic Leap chip.

magic-leap-combiner-cropLooking at the Magic Leap chip” (right) there is not obvious place for light to be “injected”.  One would expect to see some discernible structure such as an angled edge or a some structure like in the ‘705 application Fig. 8 for injecting the light. Beyond this, what about the injecting multiple images for the various focus layers.  There is a “tab” at the top which would seem to be either for mounting or it could be a light injection area for a surface injection like Hololens, but then I would expect to see some blurring/color or other evidence of diffractive structure (like Hololens does) to cause the light to bend about 45 degrees for TIR in such a short distance.

Another concern is that you don’t see any structure other than some blurring/diffusion in the Magic Leap chip.  Notice in both the Lumus and Microsoft combiners you can see structures, a blurring/color change in the case of Hololens and the exit prisms in the case of Lumus.

Beyond this if they are using their piezo scanned laser fiber display, it generates a light spiral angular cone of light that has to be “columated” (make the light rays parallel which is shown in the patent applications) so they can make their focus effects work. There would need to be a structure for doing the columation.   If they are using a more conventional display such as DLP, LCOS, or MicroOLED they are going to need a larger light injection area.

My conclusion is that at best this Magic Leap chip shown is either part of their combiner (one layer) or just a mock-up of what they hope to make someday.   I haven’t had a chance to look at or through it and anyone that has is under NDA, but based on the evidence I have, it seems unlikely that what is shown is function.

Pupil/Eyebox

I’m curious to see how small/critical the pupil/eyebox will be for their combiner.   On the one hand they want light at a the right angles to create the focusing effects and on the other hand they will will diverse/diffused light to give a large enough pupil/eyebox which could be at a cross purpose.  I’m wondering how critical it will be to position the eye in precisely the right place.   This is a question and not a criticism per say.

What, Himax LCOS? Business Insider OCT 27, 2016 (“Magic Leap Lite”?)

I had been studying the various patents and articles for some time and then last week’s Business Insider (see: http://www.businessinsider.in/Magic-Leap-could-be-gearing-up-for-a-2017-launch/articleshow/55097808.cms) throws a big curve ball.  The article attributes KGI Securities analyst Ming-Chi Kuo as saying:

“the high cost of some of Magic Leap’s components, such as a micro projector from Himax that costs about $35 to $45 per unit.”

I have no idea as to whether this is true or not, but if true it suggests something very different.   Using a Himax LCOS device is inconsistent with about everything Magic Leap has filed patents on. Even the sequentially focusing display would at best be tough with the Himax LCOS as it has a significantly lower field sequential rate than DLP.

If true, it would suggest that Magic Leap going to put out a “Magic Leap Very Lite” product based around some of their developments. Maybe this will be more of a software, user interface, and developer device. But I don’t see how they get close to what they have talked about to date.  The highest resolution Himax production device is 1366×768.

More Observations on Stanford’s Compressive Display and Magic Leap

Both are based on greatly reducing the image content from the general/brute force case so that a feasible system might be possible.  The Stanford approach is different from what Magic Leap appears to be doing.  The Stanford System has a display panel and a “modulator” panel that selects the lights rays (via controlling the angle of light that gets through) from display panel.  In contrast Magic Leap generates multiple layers of images with different focus associated with each layer in an additive manner.   This should mean that there two approaches to things like “occlusion” where parts of an image hide something behind it will have to be different (it would seem to be more easily dealt with in the Stanford approach I would think).

A key point that Dr. Wetztein makes is that brute force light fields (ala Nvidia which hugely sacrifices resolution) are impractical (too much to display and too much to process) so you have to find ways to drastically reduce the display information.  Dr. Wetztein also comments (a passing comment in the video) the that the problems are greatly reduced if you can track the eye.  Reducing the necessary image content has to be at the hear the heart of Magic Leap as well.  In all the incarnations in the patent art and Magic Leap’s comments point to supporting simultaneously two or more focus points.   Eye tracking is another key point in Magic Leap’s patents.

One might wonder if you can eye track and if you can tell the focus point of the eyes, you could eliminate the need to the light field display altogether and generate an image that appears to be focused and blurred based on the focus point of the eye.  Dr. Wetztein points out that one of the big reasons for having light fields is to deal with the eyes focus not agreeing with where the two eyes are aimed

Conclusion

Summing it all up, I am skeptical that Magic Leap is going to live up to the hype, at least anytime soon.  $1.4B can buy a lot of marketing as well as technology development, but it looks to me that to accomplish what Magic Leap wants to do, is not going to be feasible for a long time. Assuming they can make it work (I wonder about the fiber scanning display), there is then the issue of feasibility (The Concord SST airplane was “possible” but it was not “feasible” for example).

If they do enter the market in 2017 as some have suggested, it is almost certainly going to be a small subset of what they plan to do. It could be like Apple’s Newton that arguably was too far ahead of its time to fulfill its vision or it could be the next SST/Segway.

Next time I am planning on writing about Magic Leap’s scanning fiber display.

AR/MR Combiners Part 2 – Hololens

hololens-combiner-with-patent

Microsoft’s Hololens is perhaps the most most well known device using flat “waveguide” optics to “combine” the real world with computer graphics. Note there are no actual “holograms” anywhere in Hololens by the scientific definition.

At left is a picture from the Verge Teardown of a Hololens SDK engine and a from a US Patent Application 2016/0231568 I have added some red and green dots to the “waveguides” in the Verge picture to help you see their outlines.

diffraction grating is a type of Diffractive Optical Element (DOE) and has a series of very fine linear structures with a period/repeated spacing on the order of the wavelengths of light (as in extremely small). hololens-diffraction-gratingA diffraction grating acts like a lens/prism to bend the light and as an unwanted side effect the light also is split separated by wavelength (see top figure at left) as well has affecting the polarization of the light. If it were a simple grating, the light would symmetrically split the light in two directions (top figure at left) but as the patent points out if the structure is tilted then more of the light will go in the desired direction (bottom figure at left).   This is a very small structure (on the order of the wavelength of the light) must be formed on the surface of the flat waveguide.

Optical waveguides use the fact that once light enters glass or clear plastics at a certain angle or shallower, it is will totally reflect, what is known as Total Internal Reflection or TIR.  The TIR critical angle is around 45 degrees for the typical glass and plastics with their coatings used in optics.

hololens-patent-sideviewHololens use the diffraction grating (52 in Fig 3B above) to bend or “incouple” the light or the light so that it will TIR (see figure at right).   The light then TIR’s off of the flat surfaces around within the glass and hits off a triangular “fold zone” (in Fig. 3B above) which causes light to turn ~90 degrees down to the “exit zone” DOE (16 in Fig. 3B).  The exit zone DOE causes the angle of the light to be reduced so it will no longer TIR so it can exit the glass toward the eye.

Another function of the waveguides, particularly the exit waveguide 16 is to perform “pupil expansion” or slightly diffusing the light so that the image can be viewed from a wider angle.   Additionally, it is waveguide 16 that the user sees the real world through and invariably it has to have some negative effect from seeing the world through a slightly diffuse diffraction grating.

Hololens is far from the first to use DOE’s to enter and exit a flat waveguide (there are many examples) and they appear to have acquired the basic technology from Nokia’s efforts of about 10 years ago.   Other’s have used holographic optical elements (HOE) which perform similar functions to DOEs and still others have use more prismatic structure in the waveguides, but each of these alternatives solves some issues as the expense of others.

A big issue for the flat combiners I have seen to date has been chroma aberrations, the breaking up of white light into colors and out of focus and haze effects.   In bending the light at about 45 degrees is like going through a “prism” and the color separate, follow slightly different paths through the waveguide and are put back together by the exit grating.  The process is not perfect and thus there is some error/haze/blur that can be multiple pixels wide. Additionally as pointed out earlier, the user is invariably looking  at the real world through the structure meant to cause the light to exit the from the waveguide toward the eye and it has to have at least some negative effect.

There is a nice short 2013 article on flat combiners by (one author being a Google employee) that discusses some of the issues with various combiners including the Nokia one on which Hololens is base.  In particular they stated:

“The main problems of such architecture are the complexity of the master fabrication and mass replication as well as the small angular bandwidth (related to the resulting FOV). In order to mimic the holographic Bragg effect, sub-wavelength tilted structures with a high aspect ratio are needed, difficult to mass replicate for low cost volume production”  

Base on what I have heard from a couple of sources, the yield is indeed currently low and thus the manufacturing cost is high in making the Hololens combiner.   This may or may not be a solvable (in terms of meeting a consumer acceptable price) problem with volume production.

hololens-odg-comparisonWhile the Hololens combiner is a marvel of optical technology, one has to go back and try and understand why they wanted a thin flat combiner rather than say the vastly simpler (and less expensive maybe by over 10X) tilted flat combiner that say Osterhout Design Group (ODG), for example, is currently using.   Maybe it is for some planned greater advantage in the long term, but when you look at the current Hololens flat combiner, the size/width of the combiner would seem to have little effect on the overall size of the resulting device.  Interestingly, Microsoft has spent about $150 million in licensing fees to ODG.

Conclusions

Now step back and look at the size of the whole Hololens structure with the concentric bands going around the users head.  There is inner band to grip the user’s head while the electronics is held in the outer band.  There is a large nose bridge to distribute the weight on the persons nose and a big curve shield (usually dark tinted) in front of the combiner.  You have to ask, did the flat optical combiner make a difference?

I don’t know reasons/rational/advantages of why Hololens has gone with a vastly more complex combiner structure.   Clearly at the present, it does not give a significant (if any) size advantage.   It almost looks like they had this high tech combiner technology and decided to use it regardless (maybe it was the starting point of the whole program).

Microsoft is likely investing several billion dollars into Hololens. Google likely spent over $1 billion on the comparatively very simple Google Glass (not to mention their investment in Magic Leap). Closely realated, Facebook spent $2b to acquire Oculus Rift. Certainly big money is being thrown around, but is it being spent wisely?

Side Comments: No Holograms Anywhere to be Found

What Microsoft calls “Holograms” are the marketing name Microsoft has given to Mixed Reality (MR).   It is rather funny to see technical people that know better stumble around saying things like “holograms, but not really holograms, . . .”  Unfortunately due to the size and marketing clout of Microsoft others such as Metavision has started calling what they are doing “holograms” too (but this does not make is true).

Then again probably over 99% of what the public thinks are “holograms” are not.  Usually they are simple optical combiner effects cause by partial reflections off of glass or plastic.

Perhaps ironically, while Microsoft talks of holograms and the product as the “Hololens” there are as best I can find no holograms used even static ones that could have been used in the waveguide optics (they use diffraction gratings instead).

Also interestingly, the patent application is assigned to Microsoft Technology Licensing, LLC., a recently separated company from Microsoft Inc.  This would appear to be in anticipation of future patent licensing/litigation (see for example).

Next Time on Combiners

Next time on this subject, I plan on discussing Magic Leap the $1.4 Billion invested “startup” and what it looks like they may be doing.   I was originally planning on covering it with Hololens, but it became clear that it was too much to try and cover in one article.

AR/MR Optics for Combining Light for a See-Through Display (Part 1)

combiners-sample-cropIn general, people find the combining of an image with the real world somewhat magical; we see this with heads up displays (HUDs) as well as Augmented/Mixed Reality (AR/MR) headsets.   Unlike Starwars R2D2 projection into thin air which was pure movie magic (i.e. fake/impossible), light rays need something to bounce off to redirect them into a person’s eye from the image source.  We call this optical device that combines the computer image with the real world a “combiner.”

In effect, a combiner works like a partial mirror.  It reflects or redirects the display light to the eye while letting light through from the real world.  This is not, repeat not, a hologram which it is being mistakenly called by several companies today.  Over 99% people think or call “holograms” today are not, but rather simple optical combining (also known as the Pepper’s Ghost effect).

I’m only going to cover a few of the more popular/newer/more-interesting combiner examples.  For a more complete and more technical survey, I would highly recommend a presentation by Kessler Optics. My goal here is not to make anyone an optics expert but rather to gain insight into what companies are doing why.

With headsets, the display device(s) is too near for the human eye to focus and there are other issues such as making a big enough “pupil/eyebox” so the alignment of the display to the eye is not overly critical. With one exception (the Meta 2) there are separate optics  that move apparent focus point out (usually they try to put it in a person’s “far” vision as this is more comfortable when mixing with the real word”.  In the case of Magic Leap, they appear to be taking the focus issue to a new level with “light fields” that I plan to discuss the next article.

With combiners there is both the effect you want, i.e. redirecting the computer image into the person’s eye, with the potentially undesirable effects the combiner will cause in seeing through it to the real world.  A partial list of the issues includes:

  1. Dimming
  2. Distortion
  3. Double/ghost images
  4. Diffraction effects of color separation and blurring
  5. Seeing the edge of the combiner

In addition to the optical issues, the combiner adds weight, cost, and size.  Then there are aesthetic issues, particularly how they make the user’s eye look/or if they affect how others see the user’s eyes; humans are very sensitive to how other people’s eye look (see the EPSON BT-300 below as an example).

FOV and Combiner Size

There is a lot of desire to support a wide Field Of View (FOV) and for combiners a wide FOV means the combiner has to be big.  The wider the FOV and the farther the combiner is from the eye the bigger the combiner has to get (there is not way around this fact, it is a matter of physics).   One way companies “cheat” is to not support a person wearing their glasses at all (like Google Glass did).

The simple (not taking everything into effect) equation (in excel) to computer the minimum width of a combiner is =2*TAN(RADIANS(A1/2))*B1 where A1 is the FOV in degrees and and B1 is the distance to farthest part combiner.  Glasses are typically about 0.6 to 0.8 inches from the eye and the size of the glasses and the frames you want about 1.2 inches or more of eye relief. For a 40 degree wide FOV at 1.2 inches this translates to 0.9″, at 60 degrees 1.4″ and for 100 degrees it is 2.9″ which starts becoming impractical (typical lenses on glasses are about 2″ wide).

For, very wide FOV displays (over 100 degree), the combiner has to be so near your eye that supporting glasses becomes impossible. The formula above will let your try your own assumptions.

Popular/Recent Combiner Types (Part 1)

Below, I am going to go through the most common beam combiner options.  I’m going to start with the simpler/older combiner technologies and work my way to the “waveguide” beam splitters of some of the newest designs in Part 2.  I’m going to try and hit on the main types, but there are many big and small variations within a type

gg-combinerSolid Beam Splitter (Google Glass and Epson BT-300)

These are often used with a polarizing beam splitter polarized when using LCOS microdisplays, but they can also be simple mirrors.  They generally are small due to weight and cost issues such as with the Google Glass at left.  Due to their small size, the user will see the blurry edges of the beam splitter in their field of view which is considered highly undesirable.  bt-300Also as seen in the Epson BT-300 picture (at right), they can make a person’s eyes look strange.  As seen with both the Google Glass and Epson, they have been used with the projector engine(s) on the sides.

Google glass has only about a 13 degree FOV (and did not support using a person’s glasses) and about 1.21 arc-minutes/pixel angular resolution with is on the small end compared to most other headset displays.    The BT-300 about 23 degree (and has enough eye relief to supports most glasses) horizontally and has dual 1280×720 pixels per eye giving it a 1.1 arc-minutes/pixel angular resolution.  Clearly these are on the low end of what people are expecting in terms of FOV and the solid beam quickly becomes too large, heavy, and expensive at the FOV grows.  Interesting they are both are on the small end of their apparent pixel size.

meta-2-combiner-02bSpherical/Semi-Spherical Large Combiner (Meta 2)

While most of the AR/MR companies today are trying to make flatter combiners to support a wide FOV with small microdisplays for each eye, Meta has gone in the opposite direction with dual very large semi-spherical combiners with a single OLED flat panel to support an “almost 90 degree FOV”. Note in the picture of the Meta 2 device that there are essentially two hemispheres integrated together with a single large OLED flat panel above.

Meta 2 uses a 2560 by 1440 pixel display that is split between two eyes.  Allowing for some overlap there will be about 1200 pixel per eye to cover 90 degrees FOV resulting in a rather chunkylarge (similar to Oculus Rift) 4.5 arc-minutes/pixel which I find somewhat poor (a high resolution display would be closer to 1 a-m/pixel).

navdy-unitThe effect of the dual spherical combiners is to act as a magnifying mirror that also move the focus point out in space so the use can focus. The amount of magnification and the apparent focus point is a function of A) the distance from the display to the combiner, B) the distance from the eye to the combiner, and C) the curvature.   I’m pretty familiar with this optical arrangement since the optical design it did at Navdy had  similarly curved combiner, but because the distance from the display to the combiner and the eye to the combiner were so much more, the curvature was less (larger radius).

I wonder if their very low angular resolution was as a result of their design choice of the the large spherical combiner and the OLED display’s available that they could use.   To get the “focus” correct they would need a smaller (more curved) radius for the combiner which also increases the magnification and thus the big chunky pixels.  In theory they could swap out the display for something with higher resolution but it would take over doubling the horizontal resolution to have a decent angular resolution.

I would also be curious how well this large of a plastic combiner will keep its shape over time. It is a coated mirror and thus any minor perturbations are double.  Additionally and strain in the plastic (and there is always stress/strain in plasic) will cause polarization effect issues, say whenlink-ahmd viewing and LCD monitor through it.   It is interesting because it is so different, although the basic idea has been around for a number of years such as by a company called Link (see picture on the right).

Overall, Meta is bucking the trend toward smaller and lighter, and I find their angular resolution disappointing The image quality based on some on-line see-through videos (see for example this video) is reasonably good but you really can’t tell angular resolution from the video clips I have seen.  I do give them big props for showing REAL/TRUE video’s through they optics.

It should be noted that their system at $949 for a development kit is about 1/3 that of Hololens and the ODG R-7 with only 720p per eye but higher than the BT-300 at $750.   So at least on a relative basis, they look to be much more cost effective, if quite a bit larger.

odg-002-cropTilted Thin Flat or Slightly Curved (ODG)

With a wide FOV tilted combiner, the microdisplay and optics are locate above in a “brow” with the plate tilted (about 45 degrees) as shown at left on an Osterhout Design Group (ODG) model R-7 with 1280 by 720 pixel microdisplays per eye.   The R-7 has about a 37 degree FOV and a comparatively OK 1.7 arc-minutes/pixel angular resolution.

odg-rr-7-eyesTilted Plate combiners have the advantage of being the simplest and least expensive way to provide a large field of view while being relatively light weight.

The biggest drawback of the plate combiner is that it takes up a lot of volume/distance in front of the eye since the plate is tilted at about 45 degrees from front to back.  As the FOV gets bigger the volume/distance required also increase.
odg-horizons-50d-fovODG is now talking about a  next model called “Horizon” (early picture at left). Note in the picture at left how the Combiner (see red dots) has become much larger. They claim to have >50 degree FOV and with a 1920 x 1080 display per eyethis works out to an angular resolution of about 1.6 arc-minutes/pixel which is comparitively good.

Their combiner is bigger than absolutely necessary for the ~50 degree FOV.  Likely this is to get the edges of the combiner farther into a person’s peripheral vision to make them less noticeable.

The combiner is still tilted but it looks like it may have some curvature to it which will tend to act as a last stage of magnification and move the focus point out a bit.   The combiner in this picture is also darker than the one in the older R-7 combiner and may have additional coatings on it.

ODG has many years of experience and has done many different designs (for example, see this presentation on Linked-In).  They certainly know about the various forms of flat optical waveguides such as Microsoft’s Hololens is using that I am going to be talking about next time.  In fact,  that Microsoft’s licensed Patent from ODG for  about $150M US — see).

Today, flat or slightly curved thin combiners like ODG is using probably the best all around technology today in terms of size, weight, cost, and perhaps most importantly image quality.   Plate combiners don’t require the optical “gymnastics” and the level of technology and precision that the flat waveguides require.

Next time — High Tech Flat Waveguides

Flat waveguides using diffraction (DOE) and/or holographic optical elements (HOE) are what many think will be the future of combiners.  They certainly are the most technically sophisticated. They promise to make the optics thinner and lighter but the question is whether they have the optical quality and yield/cost to compete yet with simpler methods like what ODG is using on the R-7 and Horizon.

Microsoft and Magic Leap each are spending literally over $1B US each and both are going with some form of flat, thin waveguides. This is a subject to itself that I plan to cover next time.

 

Near Eye AR/VR and HUD Metrics For Resolution, FOV, Brightness, and Eyebox/Pupil

Image result for oculus riftI’m planning on following up on my earlier articles about AR/VR Head Mounted Displays
(HMD) that also relate to Heads Up Displays (HUD) with some more articles, but first I would like to get some basic Image result for hololenstechnical concepts out of the way.  It turns out that the metrics we care about for projectors while related don’t work for hud-renaultmeasuring HMD’s and HUDs.

I’m going to try and give some “working man’s” definitions rather than precise technical definitions.  I be giving a few some real world examples and calculations to show you some of the challenges.

Pixels versus Angular Resolution

Pixels are pretty well understood, at least with today’s displays that have physical pixels like LCDs, OLEDs, DLP, and LCOS.  Scanning displays like CRTs and laser beam scanning, generally have additional resolution losses due to imperfections in the scanning process and as my other articles have pointed out they have much lower resolution than the physical pixel devices.

When we get to HUDs and HMDs, we really want to consider the angular resolution, typically measured in “arc-minutes” which are 1/60th of a degree; simply put this is the angular size that a pixel covers from the viewing position. Consumers in general haven’t understood arc-minutes, and so many companies have in the past talked in terms of a certain size and resolution display viewed from a given distance; for example a 60-inch diagonal 1080P viewed at 6 feet, but since the size of the display, resolution and viewing distance are all variables its is hard to compare displays or what this even means with a near eye device.

A common “standard” for good resolution is 300 pixels per inch viewed at 12-inches (considered reading distance) which translates to about one-arc-minute per pixel.  People with very good vision can actually distinguish about twice this resolution or down to about 1/2 an arc-minute in their central vision, but for most purposes one-arc-minute is a reasonable goal.

One thing nice about the one-arc-minute per pixel goal is that the math is very simple.  Simply multiply the degrees in the FOV horizontally (or vertically) by 60 and you have the number of pixels required to meet the goal.  If you stray much below the goal, then you are into 1970’s era “chunky pixels”.

Field of View (FOV) and Resolution – Why 9,000 by 8100 pixels per eye are needed for a 150 degree horizontal FOV. 

As you probably know, the human eye’s retina has variable resolution.  The human eyes has roughly elliptical FOV of about 150 to 170 degrees horizontally by 135 to 150 degrees vertically, but the generally good discriminating FOV is only about 40 degree (+/-20 degrees) wide, with reasonably sharp vision, the macular, being about 17-20 degrees and the fovea with the very best resolution covers only about 3 degrees of the eye’s visual field.   The eye/brain processing is very complex, however, and the eye moves to aim the higher resolving part of the retina at a subject of interest; one would want the something on the order of the one-arc-minute goal in the central part of the display (and since having a variable resolution display would be a very complex matter, it end up being the goal for the whole display).

And going back to our 60″, 1080p display viewed from 6 feet, the pixel size in this example is ~1.16 arc-minutes and the horizontal field of view of view will be about 37 degrees or just about covering the generally good resolution part of the eye’s retina.

Image result for oculus rift

Image from Extreme Tech

Now lets consider the latest Oculus Rift VR display.  It spec’s 1200 x 1080 pixels with about a 94 horz. by 93 vertical FOV per eye or a very chunky ~4.7 arc-minutes per pixel; in terms of angular resolution is roughly like looking at a iPhone 6 or 7 from 5 feet away (or conversely like your iPhone pixels are 5X as big).   To get to the 1 arc-minute per pixel goal of say viewing today’s iPhones at reading distance (say you want to virtually simulate your iPhone), they would need a 5,640 by 5,580 display or a single OLED display with about 12,000 by 7,000 pixels (allowing for a gap between the eyes the optics)!!!  If they wanted to cover the 150 by 135 FOV, we are then talking 9,000 by 8,100 per eye or about a 20,000 by 9000 flat panel requirement.

Not as apparent but equally important is that the optical quality to support these types of resolutions would be if possible exceeding expensive.   You need extremely high precision optics to bring the image in focus from such short range.   You can forget about the lower cost and weight Fresnel optics (and issues with “God rays”) used in Oculus Rift.

We are into what I call “silly number territory” that will not be affordable for well beyond 10 years.  There are even questions if any know technology could achieve these resolutions in a size that could fit on a person’s head as there are a number of physical limits to the pixel size.

People in gaming are apparently living with this appallingly low (1970’s era TV game) angular resolution for games and videos (although the God rays can be very annoying based on the content), but clearly it not a replacement for a good high resolution display.

Now lets consider Microsoft’s Hololens, it most criticized issue is is smaller (relative to the VR headsets such as Oculus) FOV of about 30 by 17.5 degrees.  It has a 1268 by 720 pixel display per eye which translates into about 1.41 arc-minutes per pixel which while not horrible is short of the goal above.   If they had used 1920×1080 (full HD) microdisplay devices which are becoming available,  then they would have been very near the 1 arc-minute goal at this FOV.

Let’s understand here that it is not as simple as changing out the display, they will also have to upgrade the “light guide” that the use as an combiner to support the higher resolution.   Still this is all reasonably possible within the next few years.   Microsoft might even choose to grow the FOV to around 40 degrees horizontally rather and keep the lower angular resolution a 1080p display.  Most people will not seriously notice the 1.4X angular resolution different (but they will by about 2x).

Commentary on FOV

I know people want everything, but I really don’t understand the criticism of the FOV of Hololens.  What we can see here is a bit of “choose your poison.”  With existing affordable (or even not so affordable) technology you can’t support a wide field of view while simultaneously good angular resolution, it is simply not realistice.   One can imaging optics that would let you zoom between a wide FOV with lower angular resolution and a smaller FOV with higher angular resolution.  The control of this zooming function could perhaps be controlled by the content or feedback from the user’s eyes and/or brain activity.

Lumens versus Candelas/Meter2 (cd/m2 or nits)

With an HMD or HUD, what we care about is the light that reaches the eye.   In a typical front projector system, only an extremely small percentage of the light that goes out of the projector, reflects off the screen and makes it back to any person’s eye, the vast majority of the light goes to illuminating the room.   With a HMD or HUD all we care about is the light that makes it into the eye.

Projector lumens or luminous flux, simply put, are a measure of the total light output and for a projector is usually measure when outputting a solid white image.   To get the light that makes it to the eye we have to account for the light hits a screen, and then absorbed, scattered, and reflects back at an angle that will get back to the eye.  Only an exceeding small percentage (a small fraction of 1%) of the projected light will make it into the eye in a typical front projector setup.

With HMDs and HUDs we talk about brightness in terms candelas-per-Meter-Squared (cd/m2), also referred to as “nits” (while considered an obsolete term, it is still often used because it is easier to write and say).  Cd/m2 (or luminance) is measure of brightness in a given direction which tells us how bright the light appears to the eye looking in a particular direction.   For a good quick explanation of lumens, cd/m2 I would recommend a Compuphase article.

Image result for hololens

Hololens appears to be “luminosity challenged” (lacking in  cd/m2) and have resorted to putting sunglasses on outer shield even for indoor use.  The light blocking shield is clearly a crutch to make up for a lack of brightness in the display.   Even with the shield, it can’t compete with bright light outdoors which is 10 to 50 times brighter than a well lit indoor room.

This of course is not an issue for the VR headsets typified by Oculus Rift.  They totally block the outside light, but it is a serious issue for AR type headsets, people don’t normally wear sunglasses indoors.

Now lets consider a HUD display.  A common automotive spec for a HUD in sunlight is to have 15,000 cd/m2 whereas a typical smartphone is between 500 and 600 cd/m2 our about 1/30th the luminosity of what is needed.  When you are driving a car down the road, you may be driving in the direction of the sun so you need a very bright display in order to see it.

The way HUDs work, you have a “combiner” (which may be the car’s windshield) that combines the image being generated with the light from the real world.  A combiner typical only reflects about 20% to 30% of the light which means that the display before the combiner needs to have on the order of 30,000 to 50,000 cd/m2 to support the 15,000 cd/m2 as seen in the combiner.  When you consider that you smartphone or computer monitor only has about 400 to 600 cd/m2 , it gives you some idea of the optical tricks that must be played to get a display image that is bright enough.

phone-hudYou will see many “smartphone HUDs” that simply have a holder for a smarphone and combiner (semi-mirror) such as the one pictured at right on Amazon or on crowdfunding sites, but rest assured they will NOT work in bright sunlight and only marginal in typical daylight conditions. Even with combiners that block more than 50% of the daylight (not really much of a see-through display at this point) they don’t work in daylight.   There is a reason why companies are making purpose built HUDs.

The cd/m2 also is a big issue for outdoor head mount display use. Depending on the application, they may need 10,000 cd/m2 or more and this can become very challenging with some types of displays and keeping within the power and cooling budgets.

At the other extreme at night or dark indoors you might want the display to have less than 100 cd/m2 to avoid blinding the user to their surrounding.  Note the SMPTE spec for movie theaters is only about 50 cd/mso even at 100 cd/m2 you would be about 2X the brightness of a movie theater.  If the device much go from bright sunlight to night use, you could be talking over a 1,500 to 1 dynamic range which turns out to be a non-trivial challenge to do well with today’s LEDs or Lasers.

Eye-Box and Exit Pupil

Since AR HMDs and HUDs generate images for a user’s eye in a particular place, yet need to compete with the ambient light, the optical system is designed to concentrate light in the direction of the eye.  As a consequence, the image will only be visible in a given solid angle “eye-box” (with HUDs) or “pupil” (with near eye displays).   There is also a trade-off in making the eyebox or pupil bigger and the ease of use, as the bigger the eye-box or pupil, the easier it will be the use.

With HUD systems there can be a pretty simple trade-off in eye-box size and cd/m2 and the lumens that must be generated.   Using some optical tricks can help keep from needing an extremely bright and power hungry light source.   Conceptually a HUD is in some ways like a head mounted display but with very long eye relief. With such large eye relieve and the ability of the person to move their whole head, the eyebox for a HUD has significantly larger than the exit pupil of near eye optics.  Because the eyebox is so much larger a HUD is going to need much more light to work with.

For near eye optical design, getting a large exit pupil is a more complex issue as it comes with trade-offs in cost, brightness, optical complexity, size, weight, and eye-relief (how far the optics are from the viewer’s eye).

Too small a pupil and/or with more eye-relief, and a near eye device is difficult to use as any small movement of the device causes you to to not be able to see the whole image.  Most people’s first encounter with an exit pupil is with binoculars or a telescope and how the image cuts offs unless the optics are centered well on the user’s eye.

Conclusions

While I can see that people are excited about the possibilities of AR and VR technologies, I still have a hard time seeing how the numbers add up so to speak for having what I would consider to be a mass market product.  I see people being critical of Hololens’ lower FOV without being realistic about how they could go higher without drastically sacrificing angular resolution.

Clearly there can be product niches where the device could serve, but I think people have unrealistic expectations for how fast the field of view can grow for product like Hololens.   For “real work” I think the lower field of view and high angular resolution approach (as with Hololens) makes more sense for more applications.   Maybe game players in the VR space are more willing to accept 1970’s type angular resolution, but I wonder for how long.

I don’t see any technology that will be practical in high volume (or even very expensive at low volume) that is going to simultaneously solve the angular resolution and FOV that some people want. AR displays are often brightness challenged, particularly for outdoor use.  Layered on top of these issues are those size, weight, cost, and power consumption which we will have to save these issues for another day.

 

Wrist Projector Scams – Ritot, Cicret, the new eyeHand

ritot-cicret-eyehand-001Wrist Projectors are the crowdfund scams that keeps on giving with new ones cropping up every 6 months to a year. When I say scam, I mean that there is zero chance that they will ever deliver anything even remotely close what they are promising. They have obviously “Photoshopped”/Fake pictures to “show” projected images that are not even close to possible in the the real world and violate the laws of physics (are forever impossible). While I have pointed out in this blog where I believe that Microvision has lied and mislead investors and showed very fake images with the laser beam scanning technology, even they are not total scammers like Ritot, Cicret, and eyeHand.

According to Ritot’s Indiegogo campaign, they have taken in $1,401,510 from 8917 suckers (they call them “backers”).   Cicret according to their website has a haul of $625,000 from 10,618 gullible people.

Just when you think that Ritot and Cicret had found all the suckers for wrist projectors, now CrowdFunder reports that eyeHand has raised $585,000 from individuals and claims to have raised another $2,500,000 in equity from “investors” (if they are real then they are fools, if not, then it is just part of the scam). A million here, $500K there, pretty soon you are talking real money.

Apparently Dell’s marking is believing these scams (I would hope their technical people know better) and has show video Ads that showed a similar impossible projectors.  One thing I will give them is that they did a more convincing “simulation” (no projecting “black”) and they say in the Ads that these are “concepts” and not real products. See for example the following stills from their Dell’s videos (click to see larger image).  It looks to me like they combined a real projected image (with the projector off camera and perpendicular to the arm/hand) and then add fake projector rays to try and suggest it came from the dummy device on the arm): dell-ritots-three

Ritot was the first of these scams I was alerted to and I help contribute some technical content to the DropKicker article http://drop-kicker.com/2014/08/ritot-projection-watch/. I am the “Reader K” that they thanked in the author’s note at the beginning of the article.  A number of others have called out the Ritot and Cicret as being scams but that did not keep them from continuing to raise money nor has it stopped the new copycat eyeHand scam.

The some of key problems with the wrist projector:

  1. Very shallow angle of projection.  Projectors normally project on a surface that is perpendicular to the direction of projection, but the wrist projectors have to project onto a surface that is nearly parallel to the direction of projection.  Their concepts show a projector that is only a few (2 to 4) millimeters above the surface. When these scammers later show “prototypes” they radically change the projection distance and projection angle.
  2. Extremely short projection distance.  The near side of the projection is only a few millimeters away while the far side of the image could be 10X or 50X further away.  There is no optics or laser scanning technology on earth that can do this.  There is no way to get such a wide image at such a short distance from the projector.  As light falls off with the square of distance, this results in an impossible illumination problem (the far side being over 100X dimmer than the near side).
  3. Projecting in ambient light – All three of the scammers show concept images where the projected image is darker than the surrounding skin.  This is absolutely impossible and violates the laws of physics.   The “black” of the image is set by the ambient light and the skin, the projector can only add light, it is impossible to remove light with a projector.  This shows ignorance and/or a callous regard for the the truth by the scammers.
  4. The blocking of the image by hairs, veins, and muscles.  At such a shallow angle (per #1 above) everything is in the way.
  5. There is no projector small enough.  These projector engines with their electronics that exist are more than 20X bigger in volume than what would be required to fit.
  6. The size of the orifice through with the light emerges is too small to support the size of the image that they want to project
  7.  The battery required to make them daylight readable would be bigger than the whole projector that they show.  These scammers would have you believe that a projector could work off a trivially small battery.
  8. Cicret and eyeHand show “touch interfaces” that won’t work due to the shallow angle.  The shadows cast by fingers working the touch interface would block the light to the rest of the image and made “multi-touch” impossible.   This also goes back to the shallow angle issue #1 above.

The issues above hold true whether the projection technology uses DLP, LCOS, or Laser Beam Scanning.

Cicret and Ritot have both made “progress reports” showing stills and  videos using projectors more than 20 times bigger and much higher and farther away (to reduce the projection angle) than the sleek wrist watch models they show in their 3-D CAD models.   Even then they  keep off-camera much/most of the electronics and battery/power-supply necessary needed to drive the optics that the show.

The image below is from a Cicret “prototype” video Feb of 2015 where they simply strapped a Microvision ShowWX+ HMDI upside down to a person’s wrist (I wonder how many thousand dollars they used engineering this prototype). They goofed in the video and showed enough of the projector that I could identify (red oval) the underside of the Microvision projector (the video also shows the distinctive diagonal roll bar of a Microvision LBS projector).  I have show the rest of the projector roughly to scale in the image below that they cropped off when shooting the video.  What you can’t tell in this video is that the projector is also a couple of inches above the surface of the arm in order to project a reasonable image.

cicret-001b

So you might think Cicret was going to use laser beam scanning, but no, their October 2016 “prototype” is showing a panel (DLP or LCOS) projector.  Basically it looks like they are just clamping whatever projector they find to a person’s wrist, there is no technology they are developing.  In this latest case, it looks like what they have done is found a small production projector taken its guts out and put it in a 3-D printed case.  Note the top of the case is going to be approximately 2 inches above a person’s wrist and how far away the image is from the projector.

cicret-002e

Ritot also has made update to keep their suckers on the hook.   Apparently Indiegogo only rule is that you much keep lying to your “backers” (for more on the subject of how Indiegogo condones fraud click here).  These updates at best show how little these scammers understood projection technology.   I guess one could argue that they were too incompetent to know they were lying.  ritot-demo-2014

On the left is a “demo” Ritot shows in 2014 after raising over $1M.  It is simply an off the shelf development system projector and note there is no power supply.  Note they are showing it straight on/perpendicular to the wrist from several inches away.

ritot-2015By 2015 Rito had their own development system and some basic optics.  Notice how big the electronics board is relative to the optics and that even this does not show the power source.

By April 2016 they showed an optical engine (ONLY) strapped to a persons wrist.  ritot-2016-04-20-at-25sCut off in the picture is the all the video drive electronics (see the flex cable in the red oval) that is off camera and likely a driver board similar to the one in the 2015 update  and the power supplies/battery.

In the April 2016 you should notice how the person’s wrist is bent to make make it more perpendicular to the direction of the projected image.  Also not that the image is distorted and about the size of an Apple watch’s image.   I will also guarantee that you will not have a decent view-able image when used outdoors in daylight.

The eyeHand scam has not shown anything like a prototype, just a poorly faked (projecting black) image.  From the low angle they show in their fake image, the projected would be blocked by the base of the thumb even if the person hold their hand flat.  To make it work at all they would have to move the projector well up the person’s arm and then bend the wrist, but then the person could not view it very well unless they hold their arm at an uncomfortable angle.  Then you have the problem of keeping the person from moving/relaxing their wrist and loosing the projection surface.   And of course it would not be view-able outdoors in daylight.

It it not like others have been trying to point out that these projectors are scams.  Google search “Ritot scam” or “Cicret scam” and you will find a number of references.  As best I can find, this blog is the first to call out the eyeHand scam:

  • The most technically in depth article was by Drop-Kicker on the Ritot scam
  • Captain Delusional has a  comic take on the Cicret scam on YouTube – He has some good insights on the issue of touch control but also makes some technical mistakes such as his comments on laser beam scanning (you can’t remove the laser scanning roll-bar by syncing the camera — also laser scanning has the same fall-off in brightness due do the scanning process).
  • Geek Forever had an article on the Ritot Scam 
  • A video about the Ritot Scam on Youtube
  • KickScammed about Ritot from 2014

The problem with scam startups is that they tarnish all the other startups trying to find a way to get started.  Unfortunately, the best liars/swindlers often do the best with crowdfunding.  The more they are willing to lie/exaggerate, the better it makes their product sound.

Indiegogo has proven time and again to have extremely low standards (basically if the company keep posting lies, they are good to go – MANY people tried to tell Indiegogo about the Ritot Scam but to no avail before Ritot got the funds). Kickstarter has some standards but the bar is not that large but at least I have not see a wrist projector on Kickstarter yet. Since the crowdfunding sites get a cut of the action whether the project delivers or not, their financial incentives are on the side of the companies and the people funding. There is no bar for companies that go with direct websites, it is purely caveat emptor.

I suspect that since the wrist projector scam has worked at least three (3) times so far, we will see other using it.   At least with eyeHand you have a good idea of what it will look like in two years (hint – like Ritot and Cicret).