A Heterodyne Interferometry System Convenient to Adjust Spectral Ratio

Abstract

The invention provides a heterodyne interference measuring system convenient in splitting ratio adjustment. The heterodyne interference measuring system comprises a laser, a polarization splitting prism and a photoelectric detector. An acousto-optic frequency shifter is arranged in front of the laser. Zero-order light generated by the acousto-optic frequency shifter is used as measuring light, and first-order diffraction light is used as reference light. The measuring light is irradiated to a measured object successively through the polarization splitting prism and a quarter-wave plate. The reflected measuring light is transmitted through the quarter-wave plate and then is irradiated to a convex lens after being reflected by the polarization splitting prism. The reference light is irradiated to a convex lens successively through the reflection of a reflector, and a half-wave plate. According to the invention, the zero-order light and the first-order diffraction light generated by the acousto-optic frequency shifter are respectively used as the measuring light and the reference light, a beam splitting device is not needed, the splitting ratio can be conveniently changed by the adjustment of a acousto-optic frequency shifter driving circuit, the intensity of the reference light is enabled to be close to the intensity of the measuring light, a relatively good interference effect is obtained, the measuring precision is improved, the adopted optical member are fewer, and the beneficial effect is substantial.

Description

technical field [0001] The invention relates to the field of laser interferometry, in particular to a heterodyne interferometry system which uses an acousto-optic frequency shifter to adjust the splitting ratio of reference light and measurement light. Background technique [0002] Due to the advantages of non-contact and high precision, laser interferometry is widely used in engineering practice, especially in the fields of displacement, velocity measurement and vibration measurement. The heterodyne method is a method of interferometry. It causes a certain frequency difference between the reference light and the measurement light to introduce a carrier. The interfering measured signal is transmitted through this carrier and received by the photodetector. This method can isolate the DC level drift caused by external environment interference. In heterodyne interference, a spectroscopic prism is generally used as a beam splitting device to divide the laser light emitted by th...

AI Technical Summary

Problems solved by technology

In this method, when adjusting the splitting ratio, it is necessary to rotate the laser or the laser output end element to change the polarization direction of the linearly polarized light, thereby using the characteristics of the polarization beam splitter to change the splitting ratio, and the adjustment process is more complicated.

In addition, more optical components are used in the optical path, resulting in low utilization rate of light energy, large space occupied by the optical path structure, and poor stability of the optical path

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