US 12,422,677 B2
Slanted surface relief grating replication by optical proximity recording
Bernard Charles Kress, Redwood City, CA (US); Ishan Chatterjee, Seattle, WA (US); Joel Steven Kollin, Seattle, WA (US); and Maria Esther Pace, Palo Alto, CA (US)
Assigned to Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed by Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed on Feb. 3, 2022, as Appl. No. 17/592,383.
Prior Publication US 2023/0273432 A1, Aug. 31, 2023
Int. Cl. G02B 5/18 (2006.01); G02B 27/01 (2006.01)
CPC G02B 27/0172 (2013.01) [G02B 5/1814 (2013.01); G02B 5/1876 (2013.01); G02B 27/0101 (2013.01); G02B 2027/0178 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method for replicating a surface relief grating (SRG) using optical proximity recording, wherein the SRG is usable in a mixed-reality display system, having a real-world side and an eye side, that combines light for virtual images and real-world images for display to a user, the method comprising:
dispensing a layer of polymer dispersed liquid crystal mixture between a top plate and a bottom waveguide substrate; placing a mask in optical proximity to the layer of polymer dispersed liquid crystal mixture;
directing at least one recording beam from a light source to the mask which interacts with the at least one recording beam to diffract at least a portion of the at least one recording beam to the layer of polymer dispersed liquid crystal mixture;
recording diffraction grating features for the SRG in the layer of polymer dispersed liquid crystal mixture onto the bottom waveguide substrate, in which the recorded diffraction grating features result from interferential exposure formed from the diffracted portion of the at least one recording beam; and
and developing the layer of polymer dispersed liquid crystal mixture to realize the SRG with a minimal bias layer by evacuating one or more portions of interferentially-unexposed mixture substantially down to the bottom waveguide substrate using plasma ashing, wherein the evacuation of the interferentially-unexposed mixture reduces virtual image light being diffracted by the SRG towards the real-world side of the display system.