	US 12,078,800 B2
	Pupil expander integrity
Timothy Smeeton, Milton Keynes (GB); Jamieson Christmas, Milton Keynes (GB); Daniel Burnham, Milton Keynes (GB); Ruisheng Lin, Milton Keynes (GB); and Rakesh Maharjan, Milton Keynes (GB)
Assigned to Envisics Ltd, Milton Keynes (GB)
Appl. No. 18/552,629
Filed by Envisics Ltd, Milton Keynes (GB)
PCT Filed Aug. 17, 2022, PCT No. PCT/EP2022/072926 § 371(c)(1), (2) Date Sep. 26, 2023, PCT Pub. No. WO2023/046375, PCT Pub. Date Mar. 30, 2023.
Claims priority of application No. 2113438 (GB), filed on Sep. 21, 2021.
Prior Publication US 2024/0168283 A1, May 23, 2024
Int. Cl. G02B 27/01 (2006.01); G02B 27/00 (2006.01)

CPC G02B 27/0081 (2013.01) [G02B 27/0093 (2013.01); G02B 27/0149 (2013.01); G02B 2027/0105 (2013.01); G02B 2027/0125 (2013.01)]

19 Claims

1. A waveguide pupil expander comprising:

first and second substantially planar reflective surfaces arranged in parallel having an optically transparent material therebetween, and

an input port for receiving input light;

wherein the first reflective surface is fully reflective and the second reflective surface is partially reflective such that input light is guided from the input port to an output port at the second partially reflective surface by a series of internal reflections;

wherein the waveguide is formed by a layered glass structure arranged to maintain the integrity of the waveguide in the event of breakage of glass; and

wherein the layered glass structure comprises a polymer-based layer comprising a polymer-based turning film arranged to change an angle of light propagating therethrough; a polymer-based louvre, or a polymer-based polariser.