Diffraction Grating Reflector for High-Speed Fixation Measurement
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Solution Overview
Problem
Existing fixation measurement devices face mechanical difficulties and torque issues when using tilted spinning reflectors or disks, particularly at high scanning rates, leading to vibrations and potential component fatigue.
Innovation Solution
The use of a reflector with a diffraction component, such as a diffraction grating or Fresnel prism, mounted vertically and rotated about its axis of symmetry, eliminates torque by achieving beam tilt through diffraction, allowing high-speed operation without inducing mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a tilted spinning reflector is used to achieve rapid fixation measurement, then measurement speed is improved, but mechanical torque and vibration increase
Solution Approach 1:
The patent replaces the mechanical tilting mechanism with an optical diffraction grating. Instead of physically tilting the reflector to achieve beam deviation, the system uses a vertically oriented diffraction grating that optically tilts the reflected beam through diffraction. This substitution eliminates the mechanical torque problems associated with tilted spinning reflectors while maintaining the ability to achieve rapid fixation measurements at high scanning rates.
2Productivity
If a tilted spinning reflector is used to achieve rapid fixation measurement, then measurement speed is improved, but mechanical stability deteriorates
Solution Approach 1:
The patent substitutes the mechanically unstable tilted reflector with an optically functional diffraction grating mounted in a stable vertical orientation. The diffraction grating achieves the necessary beam tilt through optical diffraction rather than mechanical inclination, allowing the reflector to spin at high rates (200Hz or more) without generating destabilizing torques or vibrations.
3Ease of operation
If a tilted spinning reflector is used to achieve beam tilt, then optical functionality is improved, but mechanical stress on components increases
Solution Approach 1:
The patent replaces the mechanical tilting approach with an optical diffraction-based approach. The diffraction grating is mounted vertically and uses diffraction to tilt the reflected beam, eliminating the need for mechanical tilting. This removes the speed-dependent torques and mechanical stresses that would otherwise act on the reflector mounting and supporting components during high-speed rotation.
4Measurement precision
If high scanning rates are used to achieve rapid measurements, then measurement accuracy is improved, but mechanical vibration increases
Solution Approach 1:
The patent substitutes the mechanically problematic tilted reflector with a vertically mounted diffraction grating. This allows the system to operate at high scanning rates (200Hz or more) necessary for accurate fixation measurements in cooperative subjects or rapid assessments, without generating the harmful vibrations and torques that would otherwise limit the maximum usable scanning rate.
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 enables efficient and stable fixation measurement at high speeds, reducing vibrations and component stress, while maintaining the accuracy of polarization-related changes in light reflection from the eye.
Implementation Method 1
The use of a reflector with a diffraction component, such as a diffraction grating or Fresnel prism, mounted vertically and rotated about its axis of symmetry, eliminates torque by achieving beam tilt through diffraction
Data Source
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AI summary
A method and apparatus for fixation measurement includes rotating a first reflector comprising a diffraction component about a rotation axis, the first reflector being configured to reflect light received from a light source onto a second reflector via the diffraction component and reflect light received from the second reflector via the diffraction component and capturing light which is reflected by the second reflector and subsequently reflected by the first reflector with one or more photodetectors.