US 12,481,155 B2
Suppression of first-order diffraction in a two-dimensional grating of an output coupler for a head-mounted display
Haiwen Wang, Stanford, CA (US); Yu Shi, Redmond, WA (US); Siddharth Buddhiraju, Redmond, WA (US); and Hee Yoon Lee, Kirkland, WA (US)
Assigned to Meta Platforms Technologies, LLC, Menlo Park, CA (US)
Filed by Meta Platforms Technologies, LLC, Menlo Park, CA (US)
Filed on Mar. 11, 2022, as Appl. No. 17/693,187.
Prior Publication US 2023/0288705 A1, Sep. 14, 2023
Int. Cl. G02B 27/01 (2006.01); F21V 8/00 (2006.01); G02B 5/18 (2006.01)
CPC G02B 27/0172 (2013.01) [G02B 5/1842 (2013.01); G02B 6/005 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system used in a head-mounted display, the system comprising:
a projector, configured to emit light;
a waveguide configured to guide light received from the projector;
a grating configured to couple light out of the waveguide, wherein:
the grating comprises a design of two or more materials having different refractive indices;
the design is repeated periodically in a first dimension and repeated periodically in a second dimension to form a two-dimensional pattern;
a refractive index of the two-dimensional pattern is approximated by a two-dimensional Fourier series comprising a first coefficient of order (1, 0), a second coefficient of order (0, 1), and a third coefficient of order (1, 1); and
the third coefficient is less than half the first coefficient and less than half the second coefficient, such that light from the (1, 1) diffraction order of the grating is suppressed.