>I presume they're going for something similar to what I'm building in one of the implementations, using switching polarisation-sensitive lenses in a stack.
The other thing they mentioned and which is feasible immediately is using a liquid lens, if the input is small.
This would be used for 45 degree combiner but too small for a waveguide exit or for Oculus size lenses.
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>Building a single FSD isn't difficult.
Building a single FSD with wide deflection (more pixels) and fast oscillation (more frames and made necessary to counteract the wider deflection) is considerably more difficult.
Building an FSD with the previous attributes an removing jitter/ distortion is more difficult.
Doing all the previous for an assembled array to line up perfectly is more difficult again.
Finally doing an array, particularly a 2D array at scale, and expecting a significant amount of them to actually work is crazy.
The FSD improvements FredzL points to are at odds with each other.
An FSD array can either use to each unit to create a different focus plane/ view or add extra pixels to the 2D resolution for any one instant of time.
One of the University of Washington papers does hint at alternative though.
In the paper it shows a fibre array (line) being placed in a thick block for better alignment.
This would prevent the fibres being vibrated to create the image.
Instead, on a single line, of a different paper they mention trying acousto-optic modulators.
Dennis Smalley had a good paper on the subject, in which ultrasonic waves travelling through a class of materials will locally change the refractive index.
Light bends by different amounts in different refractive indices, thereby allowing the possibility of image formation.
Solid-state scanning arrays or even multiple beams on a MEMS mirror are probably better than FSDs.
They might be able to use FSD, I don't think it's a good idea.