Laser Interferometer Vibration Modulation for Displacement Measurement
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Solution Overview
Problem
Existing laser interferometers face challenges in accurately demodulating the beat signal for measuring vibration velocity and displacement when the vibration state of the object does not satisfy predetermined conditions, leading to inaccurate measurements.
Innovation Solution
A laser interferometer configuration that includes a light source, an optical modulator with a vibrator to generate modulated laser light, a photodetector to receive interference light, and an optical path length variable section to adjust the optical path length, allowing for precise demodulation of the sample signal and enabling accurate measurement of object displacement and vibration velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a demodulation process that splits the light reception signal into two and applies separate arithmetic processing is used, then the beat signal can be demodulated, but when the vibration state of the object does not satisfy predetermined conditions, the measurement precision deteriorates
Solution Approach 1:
The patent applies parameter changes by modulating the reference light beam frequency using a vibrator (piezo element or quartz crystal resonator) and varying the vibration frequency by changing the voltage. This allows the system to adapt to different vibration states of the object and achieve high-accuracy demodulation across various conditions, resolving the contradiction between measurement precision and adaptability
2Measurement precision
If the frequency of the reference light beam is shifted over time, then the beat signal can be obtained, but the demodulation accuracy deteriorates when the object's vibration state does not meet predetermined conditions
Solution Approach 1:
The patent employs dynamics by using a vibrator with variable vibration frequency that can be adjusted by changing the voltage. This dynamic adjustment capability allows the reference light beam frequency shift to adapt to different object vibration states, maintaining high measurement accuracy across various conditions rather than being limited to predetermined vibration states
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 configuration enables high-accuracy demodulation of the sample signal, even when the object's vibration state does not meet predetermined conditions, thereby improving the measurement precision of displacement and vibration velocity.
Implementation Method 1
an optical modulator that includes a vibrator and modulates the first laser light by using the vibrator to generate second laser light including a modulated signal
Implementation Method 2
a photodetector that receives interference light between third laser light including a sample signal generated by reflecting the first laser light on an object and the second laser light
Implementation Method 3
an optical path length variable section that changes an optical path length of an optical path through which the third laser light propagates
Data Source
AI summary
A laser interferometer includes a light source that emits first laser light, an optical modulator that includes a vibrator and modulates the first laser light by using the vibrator to generate second laser light including a modulated signal, a photodetector that receives interference light between third laser light including a sample signal generated by reflecting the first laser light on an object and the second laser light to output a light reception signal, and an optical path length variable section that changes an optical path length of an optical path through which the third laser light propagates.