Triangular Prism Optical Path Adjustment for Ocular Axial Length Measurement
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Solution Overview
Problem
Conventional eye measurement apparatuses require prolonged measurement times and exert a significant burden on examinees due to the need for multiple reciprocations of the optical-path-length varying optical member to accurately measure distances between eye components.
Innovation Solution
The apparatus employs a triangular prism as an optical-path-length varying optical member, which is moved in one direction to adjust the optical path difference between measurement light paths, allowing for simultaneous measurement of ocular axial length on both directions of travel, thereby reducing the number of reciprocations and measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical-path-length varying optical member reciprocates multiple times to ensure measurement accuracy, then measurement precision is improved, but measurement time is prolonged and burden on examinee increases
Solution Approach 1:
The patent implements continuous measurement by detecting interference signals throughout the entire reciprocal movement of the optical member. Instead of stopping at each endpoint to perform separate measurements, the system continuously monitors for interference signals during the sweeping motion, allowing multiple measurements to be obtained in a single reciprocation cycle. This eliminates idle time between measurements and maintains continuous useful action.
Solution Approach 2:
The patent performs preliminary positioning by moving the optical member to a starting position before measurement begins. The control unit pre-establishes the measurement protocol and prepares the detection system. During the subsequent reciprocal movement, the system is already prepared to detect and process interference signals immediately, eliminating setup time for each individual measurement.
2Reliability
If the optical-path-length varying optical member reciprocates multiple times to obtain sufficient measurement data, then measurement reliability is improved, but the number of reciprocations increases measurement time
Solution Approach 1:
The patent merges multiple measurement functions into a single reciprocal movement cycle. By detecting interference signals at multiple positions during one sweeping motion and combining these measurements, the system achieves reliable results without requiring separate reciprocation cycles. Multiple measurement points are combined into one coherent measurement process, improving both reliability and efficiency.
Solution Approach 2:
The patent utilizes periodic reciprocal movement of the optical member as the basis for measurement. Each reciprocation cycle follows a regular pattern that allows systematic data collection at predetermined intervals. This periodic action ensures consistent measurement conditions while maintaining efficient timing, as the system knows exactly when and where to expect interference signals during each cycle.
3Measurement precision
If the optical member is moved slowly to allow accurate detection of interference signals, then measurement precision is improved, but measurement time is prolonged
Solution Approach 1:
The patent employs feedback mechanisms where the control unit continuously monitors the position of the optical member and the output of the photodetector. When an interference signal is detected, the system provides feedback to confirm successful measurement and can adjust subsequent measurement parameters. This real-time feedback allows the system to maintain accurate detection without requiring excessively slow movement, as the feedback loop ensures no signals are missed.
Solution Approach 2:
The patent implements dynamic measurement where the optical member moves at controlled speeds during the sweeping phase and can pause or adjust speed when interference signals are detected. The system adapts its speed dynamically based on measurement conditions - moving faster when no signals are expected and slowing down or pausing when interference patterns are detected, optimizing both speed and detection accuracy throughout the measurement process.
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 enables continuous and accurate measurement of ocular axial length with reduced examination time and burden on the examinee, allowing for stable and high-accuracy results with fewer reciprocations of the optical member.
Implementation Method 1
a photo-receiving optical system arranged to photo-receive reflection light from the two sections as interference light by a photodetector
Data Source
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AI summary
An apparatus for measuring a distance between eye components includes an interference optical system including a light source, a beam splitter splitting light into first and second light, a projection optical system projecting the first and/or second light onto the eye, a photo-receiving optical system synthesizing the first light reflected from the eye and the second light, and an optical-path-length varying optical member disposed on one of light optical paths to be movable in an optical axis direction and adjusting a relationship between light optical path lengths, a mechanism obtaining a travel position of the member, and a unit controlling a driving unit to move the member toward one direction of the axis direction and toward the reverse direction, obtaining interference signals respectively while moving the optical member toward the directions, and calculating distances between the components based on the travel position where the signals are obtained.