Ophthalmologic Apparatus Non-Linear Scanner Correction
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Solution Overview
Problem
Optical scanners, such as galvano scanners, struggle to operate at high speeds and wider deflection angles required for high-definition and wide-angle OCT measurements, limiting the acquisition of desired measurement results.
Innovation Solution
An ophthalmologic apparatus and method that controls the optical scanner to perform OCT measurements by synchronizing the deflection operation with predetermined deflection angles and timings, allowing for A-scan data acquisition at substantially equal intervals despite non-linear operations of the scanner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical scanner operates at higher deflection speeds to achieve wider-angle and high-definition OCT measurements, then the measurement coverage and image quality improve, but the scanner cannot maintain accurate positioning and linearity due to its physical operating limitations
Solution Approach 1:
The system acquires actual position information from the optical scanner and uses this feedback to calculate correction values for movement command values. The controller applies these correction values to compensate for positioning errors, enabling accurate OCT measurements even when the scanner operates at high speeds or wide deflection angles where traditional constant-speed operation cannot maintain linearity.
Solution Approach 2:
The system changes the operational parameters by transitioning from constant-speed deflection operation to variable-speed operation with correction. The controller dynamically adjusts movement command values based on actual position feedback, allowing the scanner to operate in regimes (high speed, wide angle) that would otherwise produce unacceptable measurement errors.
2Area of stationary object
If the optical scanner operates at wider deflection angles to achieve wider-angle OCT measurements, then the field of view expands, but the linearity of the scanning trajectory deteriorates due to non-linear scanner characteristics
Solution Approach 1:
The system continuously monitors the actual position information of the optical scanner and uses this feedback to calculate and apply correction values to the movement command values. This feedback mechanism compensates for the non-linear scanning trajectory that occurs at wide deflection angles, maintaining measurement accuracy across the expanded field of view.
Solution Approach 2:
The system performs correction calculation in advance by determining correction values based on actual position information before executing the corrected movement commands. This preliminary correction action ensures that trajectory linearity is maintained throughout the wide-angle scanning process.
3Manufacturing precision
If constant correction calculation is performed on movement command values to ensure scanning linearity, then the scanning accuracy improves, but the system complexity increases
Solution Approach 1:
The system uses the optical scanner's own actual position information to generate correction values, making the correction process self-contained within the existing scanner control architecture. This self-service approach maintains scanning accuracy without requiring external complex correction systems.
Solution Approach 2:
The controller performs multiple functions: it generates original movement commands, acquires actual position information, calculates correction values, and applies corrections. This multi-functionality consolidates the correction system within the existing controller, avoiding additional complex hardware while maintaining scanning accuracy.
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
Enables the acquisition of high-definition tomographic images by compensating for non-linear scanner operations, facilitating wider-angle OCT measurements without the need for increased deflection speeds.
Implementation Method 1
an optical scanner capable of deflecting light in a predetermined deflection angle range
Implementation Method 2
acquire data of a subject's eye by performing A-scan on the subject's eye using optical coherence tomography by measurement light deflected by the optical scanner
Data Source
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AI summary
An ophthalmologic apparatus includes an acquisition unit and a controller. The acquisition unit includes an optical scanner capable of deflecting light in a predetermined deflection angle range. The acquisition unit is configured to acquire data of a subject's eye by performing A-scan on the subject's eye using optical coherence tomography by measurement light deflected by the optical scanner. The controller is configured to cause the acquisition unit to perform A-scan based on a deflection operation state of the optical scanner.