Researchers from Facebook’s Research and development department, Facebook Reality Labs, and the University of California, Berkeley have published new research that demonstrates a method for expanding the field-of-view of holographic displays. The paper that describes its mechanism is entitled High-Resolution Étendue Expansion for Holographic Displays.
The researchers explain that the relationship between the display’s field-of-view and its eye-box is that of inversion, so in order to keep any image visible, it is necessary that the eye-box should be large.
The researchers had to overcome a number of difficulties ranging from retaining a 120-degree horizontal field-of-view while keeping it compatible with a holographic display that uses a 10mm eye-box.
The way out of this sticky situation would be to use a holographic display with a resolution of 32,500 × 32,500 which is impractical.
The researches made a radical departure from the traditional view and decided to decouple the link between field-of-view and eye-box in the holographic display using what is called the étendue, i.e., the use of a scattering element placed in front of the display which scatters the light to expand its cone of propagation.
This method too came face to face with another problem, in response to which the researchers developed an algorithm that will compensate for the scattering element in such a way that the scattered light forms a proper image.
The researchers have successfully developed a benchtop prototype of their proposal to be later integrated into the said holographic display.
The paper further claims,
“The prototype presented in this work is intended as a proof-of-concept; the final design is ideally a wearable display with a sunglasses-like form factor. Starting with the design presented by Maimone et al. , which had promising form factor and FoV but very limited eyebox, we propose integrating our scattering mask into the holographic optical element that acts as an image combiner.”
This particular research is different from Facebook’s other research in this same area that deals with holographic folded optics. This new research will help to accelerate previous research done in this field, or so the researchers claim.