Sequential Eye Illumination for Gaze Tracking
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Solution Overview
Problem
Existing optical systems in electronic devices, such as virtual or augmented reality headsets, face challenges with scattered light increasing background noise and reducing contrast due to infrared light scattering, which affects the signal-to-noise ratio in gaze tracking operations.
Innovation Solution
The system employs a waveguide with optical couplers and an infrared emitter to sequentially illuminate different regions of the eye with infrared light, using a scanning mirror, adjustable light sources, or diffractive gratings to minimize scattering, thereby improving the signal-to-noise ratio by directing light and reflected light through the waveguide for precise gaze tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared light is used to illuminate the eye for gaze tracking, then the ability to perform optical sensing is improved, but scattered light increases background noise and reduces contrast
Solution Approach 1:
The illumination is divided into multiple sequential segments, where different regions of the eye are illuminated at different times rather than simultaneously. This temporal segmentation allows the sensor to capture reflected light from each region separately, eliminating scattered light from other regions that would otherwise create background noise and reduce contrast.
Solution Approach 2:
The system employs periodic illumination of different eye regions through sequential activation of light sources or scanning mechanisms. By illuminating each region in a periodic sequence rather than continuously, the system captures reflected light during specific time windows when only the target region is illuminated, thereby minimizing background noise from scattered light in other regions.
2Loss of information
If multiple regions of the eye are illuminated simultaneously, then comprehensive gaze data is obtained, but background noise increases and signal-to-noise ratio decreases
Solution Approach 1:
The comprehensive gaze data acquisition is achieved through temporal segmentation rather than spatial simultaneity. Each eye region is illuminated and measured in separate time slots, ensuring that the sensor receives clean reflected light signals without contamination from scattered light of other regions. The complete gaze information is reconstructed by combining these sequential measurements.
Solution Approach 2:
The system performs preliminary selective illumination of specific eye regions in a predetermined sequence before capturing the reflected light. This preliminary action ensures that when the sensor measures a particular region, only that region is illuminated, preventing background noise from other regions and maximizing the signal-to-noise ratio for each measurement.
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 approach minimizes background noise and maximizes the signal-to-noise ratio in sensor data, enhancing the accuracy of gaze tracking operations by reducing stray light and improving contrast in optical sensor data.
Implementation Method 1
A waveguide may receive the sensing light and may direct the sensing light towards the optical sensor
Implementation Method 2
An input coupler may couple the image light into the waveguide. An output coupler may couple the image light out of the waveguide
Implementation Method 3
A first optical coupler may couple the infrared light into the waveguide. A second optical coupler may couple the infrared light out of the waveguide
Implementation Method 4
An optical emitter that emits infrared light
Implementation Method 5
a scanning mirror that couples the light into the waveguide at different angles at different times
Implementation Method 6
the optical emitter may emit light at different wavelengths that are directed in different directions by diffractive gratings
Data Source
AI summary
A display may include an optical emitter that emits infrared light, a first coupler that couples the infrared light into a waveguide, and a second optical coupler that couples the infrared light out of the waveguide and towards the eye box. The infrared light may reflect off an eye as reflected light. The second optical coupler may couple the reflected light into the waveguide and the first optical coupler may couple the reflected light out of the waveguide and towards a camera for performing gaze tracking operations based on the sensor data. The display may sequentially illuminate different regions of the eye with the infrared light at different times using a scanning mirror, an array of light sources, or a wavelength-adjustable light source and gratings. This may minimize infrared light scattering, which minimizes background generation and maximizes signal-to-noise ratio for gaze tracking operations.