Out-of-Plane IR Illumination Module for Compact Eye Tracking
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Solution Overview
Problem
Conventional mixed-reality systems face discomfort issues due to bulky eye tracking cameras positioned near the user's eyes and require a reduction in the size of laser-based systems to achieve more compact hardware packaging.
Innovation Solution
An improved illumination system with a reduced z-dimensional profile is achieved by reflecting light out of plane relative to the optical axis, utilizing an infrared illumination device, collimating optics, and a waveguide, which allows for eye tracking and iris detection using a scanning waveguide display instead of cameras, and reduces the size of the IR illumination module by redirecting light out of the plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bulky eye tracking cameras are positioned near the user's eyes to track eye movements and perform iris detection, then eye tracking and iris recognition functionality is achieved, but user discomfort increases and device size increases
Solution Approach 1:
The patent replaces mechanical camera-based eye tracking systems with an optical illumination system using IR LEDs and waveguides. The IR illumination device emits infrared light that is directed through a waveguide onto the user's eye, and reflected light is captured by photodetectors integrated into the same optical path, eliminating the need for separate bulky cameras near the user's eyes
Solution Approach 2:
The illumination system performs multiple functions: it provides infrared illumination for eye tracking, enables iris detection through the same optical path, and integrates both functions within a single compact module rather than requiring separate camera systems for each function
2Manufacturing precision
If traditional in-plane collimating optics are used in the IR illumination module, then light collimation is achieved, but the z-dimensional profile and overall module size increase
Solution Approach 1:
The patent transitions from in-plane collimation to out-of-plane collimation by positioning the collimating optics above the IR LED rather than beside it. The infrared light travels vertically upward through the waveguide, allowing collimation to occur in the z-dimension perpendicular to the PCB plane, which reduces the module's footprint and overall size while maintaining effective collimation
3Measurement precision
If additional camera hardware is used for eye tracking and iris detection, then detection accuracy is improved, but device complexity and packaging difficulty increase
Solution Approach 1:
The patent combines the illumination function (IR LEDs) and detection function (photodetectors) into a single integrated optical module. The same waveguide structure that directs illumination to the eye also guides reflected light to the photodetectors, merging what would traditionally be separate illumination and detection subsystems into one compact unit
Solution Approach 2:
The waveguide structure serves dual purposes: it acts as both the illumination delivery path and the detection signal path. The reflected infrared light from the user's eye naturally returns through the same waveguide to the photodetectors, allowing the system to use its own structural components for both sending and receiving optical signals without requiring additional separate pathways
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 eliminates the need for additional camera hardware, reduces user discomfort, and enables more compact and efficient packaging of mixed-reality system components, allowing for seamless eye tracking and iris detection.
Implementation Method 1
The turning optic receives IR light generated by the IR illumination device and reflects this IR light as reflected IR light. The reflected IR light is reflected out of plane relative to the IR illumination device towards the collimating optic.
Implementation Method 2
The collimating optic receives the reflected IR light, collimates the light, and emits collimated IR light.
Implementation Method 3
The waveguide is positioned in a fixed position relative to the collimating optic and includes an input port or grating to receive the collimated IR light.
Data Source
Figure 1
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Figure 3A~3B
AI summary
An illumination system having a reduced z-dimensional profile, which is achieved by reflecting light out of plane relative to a light source that generated the light, is disclosed herein. This illumination system includes an IR illumination device, a collimating optic, a turning optic, and a waveguide. The turning optic is specially configured to receive IR light from the IR illumination device and to reflect the IR light out of plane relative to the emission orientation of the IR illumination device. The reflected IR light is reflected towards the collimating optic. The waveguide is positioned in a fixed position relative to the collimating optic and includes an input port or grating to receive the collimated IR light. By reflecting light out of the plane, the size of the illumination system can be beneficially reduced in the z-direction.