US 12,461,363 B1
Dispersion-compensated optical assembly and system
Pavel Trochtchanovitch, Redmond, WA (US); Yun-Han Lee, Redmond, WA (US); Zhisheng Yun, Sammamish, WA (US); Hyunmin Song, Redmond, WA (US); Sascha Hallstein, Saratoga, WA (US); and Yusufu Njoni Bamaxam Sulai, Snohomish, WA (US)
Assigned to Meta Platforms Technologies, LLC, Menlo Park, CA (US)
Filed by Meta Platforms Technologies, LLC, Menlo Park, CA (US)
Filed on Jan. 20, 2022, as Appl. No. 17/580,534.
Int. Cl. G02B 27/00 (2006.01); G02B 5/18 (2006.01); G02B 5/32 (2006.01)
CPC G02B 27/0037 (2013.01) [G02B 5/1866 (2013.01); G02B 5/32 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An optical assembly comprising:
a first grating having a first pitch, for deflecting a polychromatic light beam in a first direction, wherein the polychromatic light beam is provided by a source at a first optical distance from the first grating; and
a second grating having a second pitch, wherein:
the second grating is disposed downstream of the first grating at a second optical distance from a virtual image of the source formed by the second grating, wherein the second optical distance is larger than the first optical distance and the second pitch is larger than the first pitch; and
the second grating is configured to deflect the polychromatic light beam in a second direction opposite to the first direction to lessen a blurring of the virtual image of the source, wherein the blurring is caused by chromatic dispersion of the first grating;
wherein at least one of the first grating or the second grating comprises a polarization volumetric hologram (PVH) comprising a liquid crystal layer with at least one fringe having a helical structure, and
wherein the first grating and the second grating are configured to propagate the polychromatic light beam through the first grating and the second grating.