High precision absolute distance measuring instrument of frequency scanning interference method

Abstract

A submillimeter scale measuring device with high precision and long distance (scores of meters to hundreds of meters) is always a difficulty and a hot point of the study in the world. The invention provides a system for carrying out absolute distance measurement with long distance and high precision by utilizing a frequency scanning interferometry, pertaining to the technical field of precision measurement. The distance measuring system essentially comprises a semiconductor laser without a mode jumping frequency scanning external cavity, a Fabry-Perot-type cavity with high precision, a reference interferometer, a measurement interferometer and a data acquisition and control system. Through the utilization of the frequency scanning interferometry of the laser, the phase difference can be directly measured, and the phase difference is in direct proportion to the measured absolute distance. The complete phase difference can be obtained by phase unwrapping so as to eliminate the indeterminacy of a mode 2Pi, and the indeterminacy of the measurement of the absolute distance does not exist. The system of the invention has the advantages of high measuring precision, speediness, stability, reliability, and the like, and is applicable to the measurement of such fields as the distance between a space synthetic aperture and a sub-aperture, formation of asteroids, survey and draw, building and military, and the like.

Description

1. Technical field [0001] High-precision, long-distance (tens to hundreds of meters) submillimeter measurement instruments have always been a difficult and hot topic in international research. The invention proposes an absolute distance measurement system for high-precision long-distance measurement by using a frequency scanning interferometry, which belongs to the technical field of precision measurement. It can be used for medium and long-distance precision distance measurement, especially for space comprehensive aperture sub-aperture distance measurement and positioning, small satellite formation, surveying and mapping, construction and military fields. 2. Background technology [0002] In recent years, more and more attention has been paid to space research at home and abroad, including multi-satellite flight formation, gravitational wave detection, arrangement and positioning of X-ray telescopes and space synthetic aperture sub-telescopes, etc. Important components of ...

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Problems solved by technology

The measurement accuracy of the time-of-flight method is greatly affected by the clock, and the general measurement accuracy is on the order of millimeters; the amplitude modulation method uses the measurement phase instead of the measurement time, which can improve the measurement accuracy, but the approximate distance of the target must be known in advance; the single-wavelength interferometry is a A commonly used high-precision distance measurement method, usually used to measure the change of relative distance. If absolute distance measurement is to be performed, the phase change cannot exceed π; the dual-wavelength interferometry uses two wavelengths for interference, and its phase difference is greatly reduced. The sensitivity of the optical path change is improved, but this method also has the uncertainty of modulus 2π, which cannot accurately realize the absolute distance measurement; the multi-wavelength interferometry improves the measurement accuracy by increasing the wavelength, but the system is more complicated and multi-frequency multiplexing The technology is difficult to implement; the frequency modulated continuous wave method uses a fixed rate of change for frequency sweeping, and only moderate resolution can be obtained due to the limitation of the sweeping frequency change

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