Eye-Tracking Diffractive Couplers on Waveguide
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Solution Overview
Problem
Conventional eye-tracking systems for head-mounted display devices add bulk, weight, and optical complications, affecting the user's viewing experience and increasing the cost of the device due to the need for multiple optical components.
Innovation Solution
An eye-tracking system that utilizes a partially transparent visible light waveguide with a microelectromechanical system (MEMS) projector to direct infrared light along the waveguide, combined with diffractive input and output couplers to efficiently track eye movement with minimal additional components, allowing for accurate gaze direction estimation without obstructing the user's view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional eye-tracking components are added to HMD device, then eye-tracking functionality is achieved, but device weight and complexity increase
Solution Approach 1:
The patent combines the eye-tracking optical path with the visible light display waveguide, allowing both functions to share the same optical infrastructure. The IR light path for eye-tracking is integrated through the visible light waveguide, eliminating the need for separate dedicated IR waveguide components and reducing overall device weight.
Solution Approach 2:
The visible light waveguide serves dual purposes: it guides visible light for the display function and simultaneously guides infrared light for eye-tracking. The diffractive couplers are designed to handle both visible and IR wavelengths, enabling a single optical component to perform multiple functions and reduce the total component count.
2Reliability
If conventional eye-tracking components are added to HMD device, then eye-tracking functionality is achieved, but device complexity and component count increase
Solution Approach 1:
The patent merges the eye-tracking optical system with the display optical system by using the same visible light waveguide for both IR and visible light transmission. This integration reduces the number of separate optical components and simplifies the overall optical architecture.
Solution Approach 2:
The diffractive couplers are designed with multi-wavelength capability to handle both visible light for display and infrared light for eye-tracking. This universal approach allows a single component type to serve multiple functions, reducing device complexity.
3Reliability
If conventional eye-tracking components are added to HMD device, then eye-tracking functionality is achieved, but user field of view is obstructed
Solution Approach 1:
The patent uses infrared light for eye-tracking illumination, which is invisible to the human eye, unlike visible light components. This allows the eye-tracking system to operate without creating visible obstructions or light emissions that would block the user's field of view, while the waveguide remains transparent to both IR and visible wavelengths.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the weight and complexity of eye-tracking systems, maintains user visibility, and enhances the user experience by providing efficient and effective eye-tracking functionality within the constraints of a head-mounted display device.
Implementation Method 1
At least one diffractive input coupler may be on an input end of the IR light path downstream of the MEMS projector to diffract at least a portion of the IR light directed by the MEMS projector
Implementation Method 2
A light source may be configured to emit at least infrared (IR) light that travels along an IR light path to impinge upon the eye of the user
Implementation Method 3
At least one diffractive output coupler may be positioned in the IR light path downstream of the at least one diffractive input coupler to receive the portion of the IR light from the at least one diffractive input coupler and direct the portion of the IR light along the IR light path toward the eye
Data Source
AI summary
An eye-tracking system includes an at least partially transparent visible light waveguide having a visible light display region configured to emit visible light to an eye of a user. A light source is configured to emit at least infrared (IR) light that travels along an IR light path to the eye of the user. A microelectromechanical system (MEMS) projector positioned in the IR light path directs the IR light. At least one diffractive input coupler on an input end of the IR light path downstream of the MEMS projector diffracts at least a portion of the IR light. At least one diffractive output coupler positioned in the IR light path downstream of the diffractive input coupler receives the IR light and directs the IR light toward the eye. At least one sensor is configured to receive the IR light after being reflected by the eye.