Waveguide system for eye tracking in augmented reality glasses form factor

This study presents a novel waveguide system for capturing eye images in augmented reality glasses. While waveguides are widely used to transfer light from display engines to users' eyes, they are typically not suitable for imaging objects at close distances (15-25mm), which is crucial for eye-tracking applications. To address this challenge, we propose innovative waveguide architectures with diffractive optical elements, specifically, met the requirement of eye-tracking systems within the constraints of the augmented reality glasses form factor. These designs enable the capture of eye images for eye-tracking purposes within the limited bandwidth of waveguide system. We validated our proposed architecture by fabricating a prototype and capturing eye robot image and test patterned screen at the eye relief distance. The captured images were evaluated by the standard methods in optics: field of view, modulation transfer function and uniformity, confirming their suitability for eye-tracking applications. Our results demonstrate that this new waveguide design satisfies sufficient image quality for effective eye-tracking. This approach is expected to revolutionize eye-tracking systems by enabling a direct view of the user's eye, which minimizes the keystone effect and allows for seamless calibration and high accuracy using a fully hidden camera integrated into the temple of the augmented reality glasses.