Epic Takedown of Attempted Smackdown of OLED for Near Eye Displays By Anonymous

From Karl Guttag's blog, noted defender of all Applications LCOS is taken on by "A". Interesting in light of the CEO of eMagin saying LCOS may be the display of today but another Technology is on the verge of supplanting it. From April but more pertinent now as eMagin's ability to ramp their manufacturing capacity is nearing lift-off.

First Guttag:
OLED – Larger pixel due to 3 color sub-pixels.  It is not clear how small this technology will scale in the foreseeable future.  OLED while improving the progress has been slow — it has been the “next great near eye technology” for 10 years.   Has a very simple optical path and potentially high light efficiency which has made it seem to many like on technology with the best future, but it is not clear how it scales to very small sizes and higher resolution (the smallest OLED pixel I have found is still about 8 times bigger than the smallest FSC LCOS pixel) .    Also it is very diffuse light and therefore the depth of focus will be low.

Now "A":

 
Karl – your LCOS bias is showing
You need to do some checking on the current state of OLED and some of your claims on pixel size are misleading as to the total BOM cost of a system
Firstly you used the example of 3 micron vs 9 micron pixel – that is going to drive a high cost difference in optics – yes you could make an HD 3micro LCOS but the optics to take that out to say 65 deg FOV where you can use that resolution would be horrendous – resolution is useless if the MTF of the optical system means you cannot see the pixels due to distortion. The smaller the pixel the harder that gets and the wrong choice means not just added cost but weight and compromises in eyebox etc – Smaller is anything but better past a certain point. Even if the resolution is lower, you still have the same magnification factors so optics remains an issue. The truth is that whilst we can make chips and components smaller, we cannot address fundamental material issues on what light does through a material – some of the new work on new methods of building up optics shows promise but that will remain limited to military uses due to cost for some time.
Also for most applications, and particularly AR, field sequential LCOS is useless unless you go to a 3 panel system and some sort of horrid to make cube – even then you are limited on the base frame rate since you have to dither to deliver grey scale. Also a LOT of LCOS solutions only really perform properly unless HEATED to 40c which is significantly higher power costs.
It is not just an issue of being fixed to the head but that in a dynamic environment, between head and eye movement, 60hz FS is just not up to the task and the image will smear. I suspect this is because in your past was more focused on fixed projectors – HMD’s with head tracked VR and true AR will need non-sequential color at much higher than 60hz to avoid all manner of human factor issues – have a look at the truly nasty Silicon Micro Display ST1080 to see why FS-LCOS is not a fit. Even Google glass will need to solve this for just data let alone true AR which they are clearly not.
An OLED panel with far better contrast ratio will be better fit for both night and day, temp means nothing from -45 to +70c (2 reasons that OLED is largely displacing LCD in military applications) and the MICROsecond non-sequential response times mean that it is ideally suited to VR/AR since you can take the frame rate and PWM high enough to eliminate motion artifacts without compromising on color depth.
LCOS and LCD have their place but to really solve the human factors issues, OLED is going to be the best fit long term.