Michelson Heterodyne Laser Vibrometer Based on Single Acousto-optic Modulation and Depolarization Spectroscopy

Abstract

The Michelson heterodyne laser vibrometer based on single acousto-optic modulation and depolarization beam splitting belongs to the field of laser interferometry; the reference arm and the measurement arm are formed by depolarization beam splitter NBS beam splitting, and the incident beam on the reference arm passes through the acousto-optic modulator to generate Diffraction, the frequency-shifted first-order diffracted light is adjusted by the beam refraction element, so that the beam propagation direction is parallel to the incident beam; by adjusting the reference cube prism, the reflected light is located above the acousto-optic modulator, so that the reference light only passes through the acousto-optic modulator once The modulator adjusts the measuring corner cube so that the light beams overlap when the reference light and the measuring light pass through the depolarization beam splitter NBS again, and interference occurs; the present invention uses fewer optical elements to realize heterodyne laser interferometry, and the optical path adjustment is simple and can be It effectively solves the problems of polarization leakage, polarization mixing, and complex optical path adjustment in the existing technical solutions, and has significant technical advantages in the field of ultra-precision vibration measurement.

Description

technical field [0001] The invention belongs to the field of laser interferometry, and mainly relates to a Michelson heterodyne laser vibrometer based on single acousto-optic modulation and depolarization splitting. Background technique [0002] As an ultra-precision measuring instrument that can trace the vibration value to the laser wavelength, the laser vibrometer is widely used in the fields of dynamic displacement measurement, vibration measurement and monitoring, ultra-precision equipment and system integration, scientific research and experiments. Laser vibrometers based on laser interferometry can be divided into two categories, homodyne and heterodyne, according to the principle. The two have significant differences in working principle, optical path structure and technical characteristics. The homodyne measurement method uses a single-frequency laser as the light source, based on the classic or improved Michelson laser interference principle, and directly measures ...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a Michael-Zehnder based on single acousto-optic modulation and depolarization splitting for the existing Mach-Zehnder heterodyne laser vibrometer technology scheme in terms of optical path structure and principle existing problems such as difficult optical path adjustment, nonlinear error, etc. The heterodyne laser vibrometer, through the innovation of optical path structure and principle, based on Michelson interferometer, uses less optical components to realize heterodyne laser interferometry, and the adjustment is simple and convenient, which can effectively solve the problem of optical path in existing technical solutions. There are problems of significant polarization leakage and polarization aliasing, and difficulty in adjusting the optical path

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