Optical Measurement Device Using Switch Interferometer for Temperature-Stable Distance
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Solution Overview
Problem
Existing optical distance measurement technologies using interference phenomena face discontinuities in coherence length due to environmental temperature fluctuations, affecting the accuracy of distance measurements.
Innovation Solution
An optical measurement device employing a splitter to separate orthogonally polarized interference light, a switch interferometer to manage optical path lengths, and a calculation processor to convert interference signals into frequency spectrums, reducing the influence of temperature-induced optical path-length fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a low-cost light source with short coherence length is used, then the device cost is reduced, but the measurement range becomes limited
Solution Approach 1:
The patent applies dynamics by making the optical path length of the reference light adjustable through a movable mirror. This allows the system to dynamically change the reference light's optical path length to match different measurement depths, enabling extended measurement range beyond the fixed coherence length limitation of low-cost light sources.
Solution Approach 2:
The patent changes the optical path length parameter of the reference light by moving the mirror along the optical axis. This parameter adjustment allows the system to compensate for the short coherence length of low-cost light sources and achieve extended measurement range while maintaining cost-effectiveness.
2Length of stationary object
If the optical path length of reference light is adjusted to expand measurement range, then the measurable range is expanded, but measurement accuracy deteriorates due to temperature-induced fluctuations
Solution Approach 1:
The patent implements feedback by detecting the optical path length of reference light and using this information to control the movable mirror's position. This feedback mechanism compensates for temperature-induced fluctuations, maintaining measurement accuracy despite environmental changes and enabling extended measurement range without sacrificing precision.
Solution Approach 2:
The patent replaces purely mechanical mirror positioning with a controlled positioning system that uses detection and control mechanisms. This substitution allows for precise, adjustable optical path length control that can compensate for environmental fluctuations, resolving the contradiction between extended range and maintained 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 precise distance measurement by stabilizing optical path lengths and minimizing the impact of environmental temperature changes, thereby improving measurement consistency and range.
Implementation Method 1
a splitter to separate orthogonally polarized interference light
Implementation Method 2
output first interference light obtained by causing two orthogonally polarized waves of the reference light to interfere with each other, second interference light obtained by causing two orthogonally polarized waves of reflected light from a target object of the measurement light to interfere with each other
Implementation Method 3
a photoelectric converter to receive each interference light, and convert the received interference light into electric signals
Data Source
AI summary
An optical measurement device includes: a splitter to split light into measurement light and reference light; a switch interferometer to output first interference light obtained by causing two orthogonally polarized waves of the reference light to interfere with each other, second interference light obtained by causing two orthogonally polarized waves of reflected light from a target object of the measurement light to interfere with each other, and third interference light obtained by causing the reference light and the reflected light to interfere with each other; a photoelectric converter to convert the interference light into electric signals; a digital converter to perform A/D conversion on the electric signals; and a calculation processor to obtain an optical path-length difference between the two orthogonally polarized waves of each of the reference light and the reflected light, and an optical path-length difference between the reference light and the measurement light.