Laser Interferometer Wavelength Feedback for Accurate Vibrometry
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Solution Overview
Problem
Laser vibrometers face decreased measurement accuracy due to changes in the wavelength of the laser beam over time, affecting the accuracy of vibration speed measurements.
Innovation Solution
A laser interferometer with an interference optical system, a gas cell, and a light source controller that stabilizes the wavelength of the laser beams by adjusting the bias current or temperature based on emitted light amount detection signals, ensuring consistent center wavelength and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser beam is used for vibration speed measurement, then the measurement function is achieved, but the measurement accuracy decreases over time due to wavelength changes
Solution Approach 1:
The patent implements a feedback control system where the detector monitors the emitted light amount from the gas cell, and the light source controller adjusts the laser wavelength based on this detection signal to maintain stable resonance conditions, thereby resolving the contradiction between measurement function and wavelength stability
Solution Approach 2:
The patent changes the operating parameters of the laser source by adjusting the injection current or temperature to shift the laser wavelength, enabling the laser to resonate with the gas in the gas cell and maintain stable wavelength for accurate measurements
2Measurement precision
If the laser wavelength is stabilized by adding control systems, then the measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The system achieves self-stabilization of the laser wavelength through the feedback mechanism, where the detector and light source controller work together to automatically maintain resonance conditions without requiring external intervention, thus improving measurement accuracy while limiting complexity growth
Solution Approach 2:
The gas cell serves multiple functions: it acts as both the medium for wavelength stabilization through resonance and as a reference for the interference measurement system, reducing the need for separate stabilization components and thereby controlling device complexity
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 enhances the accuracy of displacement and speed measurements by stabilizing the wavelength of the laser beams, reducing variations in interference light and maintaining a high signal-to-noise ratio.
Implementation Method 1
a gas cell (71) which seals a gas (Cs) absorbing light having a predetermined wavelength (894.6nm) in and allows the laser beams (L1) to be incident
Implementation Method 2
an interference optical system (50) including a laser source (2) which emits laser beams (L1) and causes different types of the laser beams (L1) to interfere with each other
Data Source
AI summary
A laser interferometer includes: an interference optical system including a laser source configured to emit laser beams and to cause the laser beams to interfere with each other; a gas cell configured to seal a gas absorbing light having a predetermined wavelength and allow the laser beams to be incident; an detector configured to detect an amount of light emitted from the gas cell and output an emitted light amount detection signal; and a light source controller configured to control a wavelength of the laser beams based on the emitted light amount detection signal.