Optical Measurement Instrument Misalignment Compensation
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Solution Overview
Problem
Optical measurement instruments face challenges in verifying correct operation when measuring model eyes due to variations in sphere and cylinder values caused by misalignment angles, which are not present when measuring human eyes, making it difficult to achieve precise alignment and meet performance tolerances.
Innovation Solution
The method involves using a model eye with a known corneal reflex to determine the misalignment angle between the optical measurement instrument and the model eye, compensating measured characteristics for this angle, and comparing them to calibration values to ensure proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical measurement instrument measures a model eye without alignment compensation, then the measurement process is simple, but the measurement precision deteriorates due to misalignment angle variations
Solution Approach 1:
The system performs preliminary detection of the corneal reflex position before conducting the actual optical measurement. By detecting the corneal reflex in advance and using it to calculate misalignment angles, the system prepares the necessary alignment data beforehand, enabling accurate compensation during the measurement process and thus maintaining high measurement precision without excessive complexity
Solution Approach 2:
The corneal reflex serves as an intermediary element that provides information about the misalignment angle. By detecting this intermediate feature (the corneal reflex position) and using it to calculate compensation values, the system indirectly obtains alignment information without requiring direct complex alignment mechanisms, thus resolving the contradiction between measurement precision and device complexity
2Measurement precision
If mechanical constraints are used to align the model eye, then the alignment accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The system replaces complex mechanical alignment constraints with an optical detection and computational compensation approach. By using the corneal reflex detection and misalignment angle calculation to compensate for alignment errors in software, the system achieves high alignment accuracy without requiring complex mechanical alignment devices, thus reducing device complexity and cost while maintaining measurement precision
3Ease of operation
If the misalignment angle is not compensated, then the operation is simple, but the measurement precision deteriorates beyond tolerable variations
Solution Approach 1:
The system performs self-alignment verification by automatically detecting the corneal reflex position and calculating the misalignment angle. This self-service approach allows the instrument to automatically compensate for its own alignment errors without requiring complex external alignment equipment or complicated operational procedures, thus maintaining ease of operation while significantly improving measurement precision through automatic misalignment compensation
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 allows for accurate verification of optical measurement instrument performance by accounting for misalignment, reducing measurement variations and ensuring the instrument operates within specified tolerances, even with significant misalignment angles.
Implementation Method 1
determining an observed location of a corneal reflex from the model eye
Data Source
AI summary
A method of compensating for misalignment between an optical measurement instrument and a model eye includes: receiving a light beam from the model eye at the optical measurement instrument; producing image data, including light spot data for a plurality of light spots, from the received light beam; determining an observed location of a corneal reflex from the model eye within an image representing the image data; and determining an angle of misalignment between an axis normal to the front surface of the model eye and the optical axis of the optical measurement instrument from the observed location of the corneal reflex within the image.