Holographic Waveguide Optical Tracker

Abstract

There is provided an object tracker comprising: a first waveguide; a source of illumination light; a detector optically coupled to said waveguide; and at least one grating lamina formed within said waveguide. Illumination light propagating along a first optical path from said source to an object in relative motion to the object tracker. Image light reflected from at least one surface of an object is deflected by said grating lamina into a second optical path towards said detector.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. application Ser. No. 15 / 513,288 filed Mar. 22, 2017, which application is a U.S. national phase of PCT Application No. PCT / GB2015 / 000274 filed on Sep. 25, 2015, which application claims the benefit of U.S. Provisional Patent Applications No. 62 / 071,534 filed on Sep. 26, 2014, U.S. Provisional Patent Applications No. 62 / 124,154 filed on Dec. 10, 2014, U.S. Provisional Patent Applications No. 62 / 125,454 filed on Jan. 22, 2015, and U.S. Provisional Patent Applications No. 62 / 179,336 filed on May 5, 2015, the disclosures of which are incorporated herein by reference in their entireties.BACKGROUND OF THE INVENTION[0002]This invention relates to sensors, and more particularly to an object tracking device using waveguide display using electrically switchable gratings.[0003]The tracking of objects is a key requirement in many fields including eye tracking (in augmented reality (AR), virtual reality (VR) ...

AI Technical Summary

Benefits of technology

This patent describes a new kind of tracker for tracking the movement of objects in real-time. It is meant to be small and easily integrated into displays, like eye-slaved displays or LIDAR systems. The tracker has a wide field of view and low latency, allowing for accurate tracking. The invention also includes a dynamic occlusion mask based on a spatial light modulator, which helps to create a more realistic visual world. Overall, this patent provides a solution for creating compact and efficient tracking systems for various applications.

Problems solved by technology

The first practical challenge is how to introduce the image sensor and illuminator in such a way that both can work efficiently while avoiding obscuring the line of sight Most eye tracker implementations in HMDs have employed flat beam splitters in front of the users' eyes and relatively large optics to image the reflections onto an imaging sensor.

In order to maximize the exit pupil, the imaging optics are positioned close to the beamsplitter, and represent a vision obscuration and a safety hazard.

Another known limitation with eye trackers is the field of view, which is generally limited by the illumination scheme in combination with the geometry of the reflected images.

The size of the corneal reflected angles would ordinarily require a large angular separation between the illumination and detection optical axes making using corneal reflections over large FOVs very difficult.

However, the latency incurred by the need to recognize and track eye features remains a significant processing bottleneck.

Although recent advances in displays have collectively spanned these requirements no one display technology possesses all of these characteristics.

The device exhibits near 100% efficiency with no voltage applied and essentially zero efficiency with a sufficiently high voltage applied.

SBGs efficiently diffract P polarized light (ie light with the polarization vector in the plane of incidence) but have nearly zero diffraction efficiency for S polarized light (ie light with the polarization vector normal to the plane of incidence.

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