Optical device having reduced diffraction artifacts for eye-tracking

Patent metadata

Field	Value
Publication number	US-11675188-B2
Application number	US-202117474362-A
Country	US
Kind code	B2
Filing date	Sep 14, 2021
Priority date	Aug 7, 2019
Publication date	Jun 13, 2023
Grant date	Jun 13, 2023

Abstract

A system is provided. The system includes a light source configured to emit an infrared light to illuminate an eye of a user. The system includes a grating disposed facing the eye and including a birefringent material film configured with a uniform birefringence lower than or equal to 0.1. The grating is configured to diffract the infrared light reflected from the eye, and transmit a visible light from a real world environment toward the eye, with a diffraction efficiency less than a predetermined threshold. The system includes an optical sensor configured to receive the diffracted infrared light and generate an image of the eye based on the diffracted infrared light.

First claim

What is claimed is:

1. A system, comprising:
a light source configured to emit an infrared light to illuminate an eye of a user;
a grating disposed facing the eye and including a polarization volume hologram (“PVH”) film configured with a uniform birefringence lower than or equal to 0.1, wherein the grating is configured to diffract the infrared light reflected from the eye, and transmit a visible light from a real world environment toward the eye with a diffraction efficiency of less than 0.5% for the visible light; and
an optical sensor configured to receive the diffracted infrared light and generate an image of the eye based on the diffracted infrared light.

2. The system of claim 1 , wherein the diffraction efficiency is less than 0.1%.

3. The system of claim 1 , wherein the diffraction efficiency is less than 0.05%.

4. The system of claim 1 , wherein the diffraction efficiency is less than 0.01%.

5. The system of claim 1 , wherein the PVH film is a reflective PVH film.

6. The system of claim 1 , wherein the PVH film includes molecules configured with in-plane molecular reorientations that change in a linearly repetitive pattern from a center to an edge of the PVH film.

7. The system of claim 1 , further including a display system configured to project a virtual image into a display window in a predetermined field of view.

8. The system of claim 7 , wherein the grating is configured to optically combine the virtual image and a real image formed by the visible light from the real world environment in the predetermined field of view.

9. The system of claim 1 , wherein the grating reduces a rainbow effect in a see-through view observed caused by a diffraction of the visible light from the real world environment toward the eye.

10. The system of claim 1 , wherein the PVH film is configured to converge or diverge the infrared light while diffracting the infrared light.

11. The system of claim 1 , wherein the PVH film is a transmissive PVH film.

Assignees

• Meta Platforms Tech Llc

Inventors

• Lee Yun-Han
• Lu Lu
• Wang Mengfei
• Peng Fenglin
• Wang Junren

Classifications

• G03H1/0465

  Particular recording light; Beam shape or geometry (G03H1/06 takes precedence) · CPC title

• G02B2027/0178

  Eyeglass type (eyeglass details G02C) · CPC title

• G02B2027/0109

  comprising details concerning the making of holograms · CPC title

• G03H2222/44

  Beam irradiating the object at recording stage · CPC title

• G02B2027/0138

  comprising image capture systems, e.g. camera · CPC title