Polarization-selective Diffractive Elements for Compact Eye Tracking
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Solution Overview
Problem
Conventional imaging optical systems for detecting the fixation state of the eyes are bulky due to the requirement of multiple detection units and optical components, which compromises measurement accuracy.
Innovation Solution
The proposed imaging optical system utilizes a first and second polarization-selective diffractive (PSD) optical element, arranged along an optical path with positive refractive power optical systems, to diffract light by specific angles, allowing for the separation and focusing of polarized components onto a single imaging device, thereby reducing system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a PBS and a plurality of detection units are used to acquire each polarization component of both eyes separately, then measurement accuracy is improved, but the optical system becomes enlarged
Solution Approach 1:
The patent combines the functions of multiple detection units into a single imaging device by using two PSD optical elements that diffract light from both eyes onto the same imaging sensor. The first PSD element separates polarization components of the first eye, and the second PSD element separates polarization components of the second eye, with all four components being imaged onto a single imaging device, thereby reducing system size while maintaining measurement accuracy
Solution Approach 2:
The patent uses diffraction angles to spatially separate different polarization components in the optical path. By controlling the diffraction angles of the PSD optical elements, light from different eyes and different polarization states are directed to different regions of the imaging sensor, enabling simultaneous detection of multiple polarization components from both eyes on a single imaging device
2Adaptability or versatility
If a prism or multiple detection units are used to detect the fixation state of both eyes, then measurement capability is improved, but the optical system becomes enlarged
Solution Approach 1:
The patent merges the detection capability for both eyes into a single imaging device by using two PSD optical elements. Each PSD element processes light from one eye and separates its polarization components, with all components being directed to the same imaging sensor, thereby achieving versatile measurement capability for both eyes without requiring separate detection units
Solution Approach 2:
The imaging device serves multiple functions by detecting polarization components from both eyes simultaneously. The two PSD optical elements enable the single imaging device to perform the work of multiple detection units, making the system universal for detecting fixation states of both eyes while maintaining a compact size
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 configuration achieves miniaturization of the imaging optical system while improving measurement accuracy by effectively separating and focusing the necessary polarized components, reducing the size of the optical system and enhancing inspection precision.
Implementation Method 1
When emitted by the first PSD optical element, the light is diffracted by a first diffraction angle and, when emitted by the second PSD optical element, the light is diffracted by a second diffraction angle that is opposite to the first angle.
Implementation Method 2
a first polarization-selective diffractive (PSD) optical element; and a second PSD optical element
Data Source
AI summary
Provided are an imaging optical system and measurement device for guiding light reflected from a retina to at least one imaging device, the system and device having a first polarization-selective diffractive (PSD) optical element and a second PSD optical element, with the retina, the first PSD optical element, and the second optical PSD element are positioned along an optical path. When emitted by the first PSD optical element, the light is diffracted by a first diffraction angle and, when emitted by the second PSD optical element, the light is diffracted by a second diffraction angle that is opposite to the first angle.