Laser Interferometer With Diffraction-Grating Crystal Oscillator
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Solution Overview
Problem
Existing laser interferometers using oscillators face challenges in accurately measuring the velocity of an object due to the variability of the oscillator's modulation signal intensity, which affects the demodulation of the Doppler signal, particularly under varying oscillation conditions.
Innovation Solution
The laser interferometer employs a sensor head unit with a frequency shifter-type optical modulator that includes a crystal oscillator with a diffraction grating, allowing for stable optical modulation and accurate demodulation of the Doppler signal by using a crystal AT oscillator with a diffraction grating and a polarized beam splitter, enabling precise measurement of object velocity and displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oscillator is used to modulate laser light instead of an acousto-optical modulator, then the cost is reduced, but the measurement accuracy deteriorates due to small modulation signal intensity
Solution Approach 1:
The patent changes the physical parameters of the oscillator system by selecting specific oscillation frequencies (10-100 MHz range) and optimizing the interaction between laser light and oscillator to maximize modulation signal intensity while maintaining cost-effectiveness
Solution Approach 2:
The patent introduces a optical modulator as an intermediary component that couples the oscillator's mechanical vibrations to the laser beam, enabling efficient energy transfer and signal generation while maintaining system affordability
2Device complexity
If the oscillation condition of the oscillator varies, then the device complexity is reduced, but the measurement precision deteriorates due to unstable modulation signal intensity
Solution Approach 1:
The patent implements a feedback mechanism where the photodetector receives both reference light and scattered light, converts them to electrical signals, and processes them to extract velocity information while compensating for oscillation condition variations
Solution Approach 2:
The patent employs dynamic signal processing techniques that adapt to varying oscillation conditions in real-time, allowing the system to maintain measurement accuracy despite changes in oscillator behavior
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 accurate measurement of object velocity and displacement by stabilizing the modulation signal, reducing the size and power consumption of the interferometer, and improving measurement accuracy through the use of a crystal oscillator with a diffraction grating, which enhances the interferometer's functionality as a displacement gauge and velocimeter.
Implementation Method 1
measures a velocity of an object by irradiating, with a laser beam, the object that is oscillating and using a frequency of the laser beam changed due to the Doppler effect
Implementation Method 2
a crystal oscillator with a diffraction grating
Implementation Method 3
a polarized beam splitter
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided is a laser interferometer including a light source configured to emit laser light, an optical divider configured to divide the laser light into a first optical path and a second optical path, the laser light being emitted from the light source, an optical modulator being provided on the first optical path or the second optical path, including an oscillator that oscillates when a current is applied, and being configured to modulate the laser light by using the oscillator, a photoreceptor configured to receive the laser light and output a photoreception signal, the laser light being reflected by an object to be measured that is provided on the first optical path or the second optical path, and a demodulation circuit configured to demodulate, from the photoreception signal, a Doppler signal derived from the object to be measured, based on a reference signal and a modulation signal, wherein Iq/f ≤ 1×10-7 is satisfied, where an amplitude value of the current applied to the oscillator that is oscillating is Iq [A] and an oscillation frequency of the oscillator is f [Hz].