Grating and Polarizer Eye-Tracking Optical System
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Solution Overview
Problem
Conventional eye-tracking systems in Head-Mounted Displays (HMDs) face reduced signal-to-noise ratio and accuracy due to surface reflection noise, which degrades the quality of eye-tracking signals and images.
Innovation Solution
An optical system with a grating structure and polarizer configuration that diffracts signal light while blocking noise light by polarizing the light reflected from the eye, ensuring the optical sensor receives only the diffracted signal light, thereby improving the signal-to-noise ratio and accuracy of eye-tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a grating is used to diffract light for eye-tracking, then the eye-tracking function is enabled, but surface reflection noise is introduced reducing signal-to-noise ratio
Solution Approach 1:
A polarizer is introduced as an intermediary component between the grating and the optical sensor. The polarizer selectively transmits light with a specific polarization state while blocking reflected noise, thereby mediating between the signal generation (grating diffraction) and detection (optical sensor) to improve signal-to-noise ratio
Solution Approach 2:
The invention changes the polarization parameter of the light passing through the grating. By orienting the polarizer's transmission axis perpendicular to the substrate surface, it selectively transmits the diffracted signal light while blocking the reflected noise light, thus changing the optical parameter (polarization) to resolve the contradiction
2Reliability
If the polarizer transmission axis is oriented perpendicular to the substrate surface, then signal light is transmitted and noise light is blocked, but this requires precise alignment
Solution Approach 1:
The polarizer is pre-oriented during manufacturing or assembly with its transmission axis perpendicular to the substrate surface. This preliminary alignment ensures that the optimal signal-to-noise ratio is achieved without requiring complex real-time adjustment mechanisms, thereby reducing operational complexity while maintaining high reliability
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
The proposed solution significantly reduces surface reflection noise, enhancing the accuracy and quality of eye-tracking in HMDs for AR, VR, and MR applications by isolating signal light from noise light using polarized filtering.
Implementation Method 1
The grating structure is configured to diffract a first light having an incidence angle within a predetermined range
Implementation Method 2
a polarizer configured to transmit the first light diffracted by the grating structure and block a second light reflected by a surface of the at least one substrate
Data Source
AI summary
An optical system includes a grating including at least one substrate and a grating structure coupled to the at least one substrate. The grating structure is configured to diffract a first light having an incidence angle within a predetermined range. The optical system also includes a polarizer configured to transmit the first light diffracted by the grating structure and block a second light reflected by a surface of the at least one substrate.