Ophthalmic Apparatus Optical Calibration System
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Solution Overview
Problem
Ophthalmic apparatuses using the Fourier domain method face challenges in accurately determining the position of a measuring portion inside an eye due to changes in light properties over time, such as temperature changes or aging of the light source, affecting the interference light received.
Innovation Solution
Incorporating an optical calibration system that uses interference light for calibration, allowing the processor to correct the position of the measuring portion by comparing the optical path lengths of different sections, thereby maintaining accuracy despite changes in light properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the Fourier domain method is used to simplify the optical system configuration, then the device complexity is reduced, but the measurement precision deteriorates over time due to changes in light source properties
Solution Approach 1:
The patent implements a feedback mechanism by introducing a calibration optical path that periodically measures the actual optical path length using interference patterns. The processor compares the measured calibration path length with the expected value and automatically corrects the position determination by applying a compensation value, thereby maintaining measurement precision despite light source property changes over time
Solution Approach 2:
The patent introduces a calibration optical path as an intermediary system that indirectly measures the light source property changes. By using a known reference path length and comparing it with the actual measured path length through interference patterns, the system creates a mediator mechanism that quantifies drift without requiring direct monitoring of light source properties
2Productivity
If the optical measurement system operates continuously without calibration, then the productivity is maintained, but the reliability of position determination deteriorates due to temperature change and aging
Solution Approach 1:
The patent implements periodic calibration by alternating between measurement mode and calibration mode. The calibration optical path is activated at regular intervals to measure and correct for drift, creating a periodic feedback loop that maintains reliability without requiring continuous calibration operations that would reduce productivity
Solution Approach 2:
The system performs preliminary calibration measurements by establishing a known reference path length before actual measurements begin. This preliminary action creates a baseline for detecting subsequent drift, allowing the system to proactively compensate for changes before they significantly impact measurement reliability
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
The ophthalmic apparatus accurately determines the position of the measuring portion inside the eye even when light properties change, ensuring precise measurements by using the optical calibration system to correct for variations in optical path lengths.
Implementation Method 1
a light receiving element receives interference light for measurement produced by both the reflected light guided by the optical measurement system and the reference light guided by the optical reference system
Data Source
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AI summary
An ophthalmic apparatus (10) is provided with a light source (12), an optical measurement system (24, 72, 48), an optical reference system (24, 22), an optical calibration system (24, 72, 74), a light receiving element (26), and a processor. The light receiving element (26) receives an interference light for measurement produced by both the reflected light guided by the optical measurement system (24, 72, 48) and the reference light guided by the optical reference system (24, 22), and also receives an interference light for calibration produced by the calibration light guided by the optical calibration system (24, 72, 74) and the reference light guided by the optical reference system (24, 22). The processor (64) determines a position of a measuring portion inside an eye (100) to be examined by Fourier-analyzing the interference light for measurement and the interference light for calibration.