I agree that the lack of coherence (spatial & temporal) of ambient lighy would makes the use of diffraction gratings to actively create destructive interference

I agree that the lack of coherence (spatial & temporal) of ambient lighy would makes the use of diffraction gratings to actively create destructive interference patterns on the retina a futile efftort. Ambient light is generally a white lighy (lacks temporal coherence) and many wavefronts originate closer to the eye than the optical infinity (~8m) and are therefore fairly divergent (curved and thus lack spatial coherence). The resulting interference patterne would therefore be very blurry. Too blurry to form a useful black pixel image on the retina. On the other hand, I believe ML is proposing to use a gratings to display black/clear images. In this setup, the incident ambient light wavefronts are selectively redirected using bragg gratings (why they keep saying Braff gratings" in their literature is beyond me). This technique has been around for many years and is still captivating to watch even in this day and age - see: https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DS5W5JJXtqhw&ved=0ahUKEwj4loTjlpnQAhXE6yYKHUb1AkEQtwIIGjAA&usg=AFQjCNGVVlv9xxrd7RlmDFyp7czhQgiiUg&sig2=1H7cDmEQ31j-uEdjVaVjLw https://www.google.com/url?sa=t&source=web&rct=j&url=https:/... The realization that this affect retains its "sharpness" for near eye applications in concert with (I believe) the realization that you can utilize the electonically-controlled diffraction grating layers you already have in your device (for the purpose of controlling wavefront curvature to support eye depth accommodation) depth is really quite clever. It's truly an exciting prospectct!