An Equal Arm Length Heterodyne Laser Interferometric Ranging System

Abstract

The invention provides an equal-arm-length heterodyne laser interferometry ranging system at least comprising a vibration isolation system, a vacuum system, a light source system, an interference system, and a phase monitoring and data analysis system. The vibration isolation system is used for isolating and filtering external low-frequency noise to eliminate system vibration noise. The vacuum system is used for reducing thermal noise caused by system temperature fluctuation. The light source system is used for providing two high-stability high-stable-frequency laser beams which have corresponding differential frequencies. The interference system is used for generating two equal-arm-length heterodyne interference signals and acquiring the information of displacement change between two tested objects according to the displacement and phase relationship. The phase monitoring and data analysis system is used for phase detection for the interference signals, acquiring phase information, inverting displacement, and indicating ranging precision of the interference system under each frequency. The equal-arm-length heterodyne laser interferometry ranging system has the advantages that frequency instability of the laser can be eliminated, the influence of various noise sources upon the ranging precision can be eliminated, and long-period picometer-level measurement precision is realized.

Description

technical field [0001] The invention relates to an equal-arm-length heterodyne laser interference ranging system, which can be used for precise measurement of displacement changes between two objects, and the ranging accuracy can reach picometer level. Background technique [0002] Laser ranging technology has many advantages such as high precision, good collimation, and strong anti-interference ability, so it is widely used in satellite remote sensing, precision measurement and processing, machinery manufacturing, engineering construction, and safety monitoring. At present, the relatively mature laser range finder uses a laser to emit laser pulses to the target, and calculates the distance of the target by measuring the round-trip time or phase of the laser pulse reaching the target and returning from the target to the receiving telescope. The laser interferometer uses a beam splitter to divide a beam of laser into two beams, one way passes through a known distance to form ...

AI Technical Summary

Problems solved by technology

In addition, the frequency instability of the laser will also cause the measurement error of the heterodyne laser interferometer due to the inequality of the reference light and the measurement light: ΔL=L·δυ / υ, where L is the light of the reference light and the measurement light δυ is the frequency instability of the laser, and υ is the frequency of the laser; at the same time, the initial phase fluctuation of the laser, as well as various noise sources caused by optical platforms, components and optical fibers, etc. will also cause system measurement errors

[0005] The current laser interferometric ranging system generally does not have a noise isolation system. At the same time, the interference optical path is unequal, and there is no related noise-cancelling reference interferometer. At the same time, due to the lack of noise isolation measures such as vibration isolation, heat insulation and electromagnetic shielding, it is impossible to achieve long-term measurement

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