US 12,078,816 B2
Grating collimator, backlight system, and method employing a light-recycling light source
Xuejian Li, Menlo Park, CA (US); Ming Ma, Palo Alto, CA (US); and David A. Fattal, Mountain View, CA (US)
Assigned to LEIA Inc., Menlo Park, CA (US)
Filed by LEIA INC., Menlo Park, CA (US)
Filed on Feb. 4, 2021, as Appl. No. 17/168,108.
Application 17/168,108 is a continuation of application No. PCT/US2018/046562, filed on Aug. 13, 2018.
Prior Publication US 2021/0157160 A1, May 27, 2021
Int. Cl. G02B 27/30 (2006.01); G02B 5/02 (2006.01); G02B 27/44 (2006.01)
CPC G02B 27/30 (2013.01) [G02B 5/0252 (2013.01); G02B 27/44 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A grating collimator comprising:
a light guide configured to guide light as guided light at a non-zero propagation angle relative to a plane of a guiding surface of the light guide, the guided light having a propagation direction toward an output of the grating collimator;
a light-recycling light source configured to provide light to the light guide and to recycle light received from the light guide, the light recycled by the light-recycling light source being configured to augment the provided light; and
a diffraction grating coupler at the guiding surface of the light guide, the diffraction grating coupler being configured to diffractively redirect the light provided by the light-recycling light source into the light guide as the guided light at the non-zero propagation angle,
wherein the light-recycling light source comprises an optical emitter configured to emit light, an optical diffuser configured to diffuse light received from the light guide, and an optical reflector configured to reflect light diffused by the optical diffuser in a direction toward the light guide as reflected diffuse light, the light emitted by the optical emitter and the reflected diffuse light being provided in combination as the light provided to the light guide.