US 12,422,601 B2
Optical element, image waveguide method, head-mounted display apparatus and diffractive waveguide display
Kuo-Feng Lin, Kaohsiung (TW); Hui-Wen Lu, Kaohsiung (TW); Wei-Chen Lin, Kaohsiung (TW); and Hui-Ching Hsueh, Kaohsiung (TW)
Assigned to Radiant Opto Electronics (Suzhou) Co., Ltd., Jiangsu (CN); and Radiant Opto-Electronics Corporation, Kaohsiung (TW)
Filed by Radiant Opto-Electronics (Suzhou) Co., Ltd., Jiangsu (CN); and Radiant Opto-Electronics Corporation, Kaohsiung (TW)
Filed on Mar. 24, 2022, as Appl. No. 17/656,422.
Application 17/656,422 is a continuation of application No. PCT/CN2020/130821, filed on Nov. 23, 2020.
Prior Publication US 2022/0214487 A1, Jul. 7, 2022
Int. Cl. G02B 5/00 (2006.01); G02B 5/18 (2006.01); G02B 6/34 (2006.01); G02B 27/01 (2006.01)
CPC G02B 5/1809 (2013.01) [G02B 5/1814 (2013.01); G02B 6/34 (2013.01); G02B 27/0172 (2013.01); G02B 2027/0125 (2013.01); G02B 2207/101 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An optical element, suitable for guiding an image beam from an image source, the optical element comprising:
a waveguide substrate, having a first side, a second side opposite to the first side, a light entering surface and a light exiting surface, the waveguide substrate configured to allow the image beam to enter the interior thereof through the light entering surface and configured to propagate the image beam between the first side and the second side of the waveguide substrate in a manner of total internal reflection, wherein the image beam exits the light exiting surface after one or more reflections;
a first optical film structure, arranged on the first side of the waveguide substrate;
a second optical film structure, arranged on the second side of the waveguide substrate; and
a sub-wavelength nanostructure, arranged on the first side of the waveguide substrate,
wherein the sub-wavelength nanostructure is configured to receive and diffract the image beam, so as to couple the image beam to the waveguide substrate,
wherein the first optical film structure and the second optical film structure are configured to reflect a part of the image beam at an incident angle inside the waveguide substrate smaller than a critical angle of the waveguide substrate,
wherein the waveguide substrate comprises a first waveguide layer and a second waveguide layer stacked alternately to each other, and a refractive index of the first waveguide layer is higher than a refractive index of the second waveguide layer.