Device and method for sinusoidal phase modulation interference absolute ranging based on femtosecond optical frequency comb

Abstract

The invention discloses a femtosecond optical frequency comb based sinusoidal phase modulation interferometric absolute distance measuring device and method. The device comprises a light source system, a sinusoidal phase modulation interferometric system and a signal processing system, wherein the light source system outputs two laser beams with different wavelengths, the laser beams are shot to the sinusoidal phase modulation interferometric system, the interferometric light beams are shot to the signal processing system for phase demodulation, and the distance to be measured is obtained according to frequency scanning interference and multi-wavelength interference principles; and the frequency scanning range in FSI (Frequency Scanning Interferometry) and the value of each wavelength in MWI (Multi-Wavelength Interferometry) are calibrated by a femtosecond optical frequency comb, and the distance measurement is directly traced to the time frequency standard. The device disclosed by theinvention is simple in optical path structure, large in measurement range, high in accuracy and capable of being applied to the fields such as large equipment manufacturing and precision metering.

Description

technical field [0001] The invention belongs to the technical field of laser interference absolute distance measurement, in particular to a sinusoidal phase modulation interference absolute distance measurement device and method based on a femtosecond optical frequency comb. Background technique [0002] With the continuous improvement of my country's advanced manufacturing level, applications such as the measurement of large precision machine tools, the assembly of large aircraft and ships, the measurement of the length of the main shaft of steam turbines and water turbines, and the monitoring of satellite positions in satellite formation flights urgently require large-scale, high-precision absolute distances. measurement technology. The time-of-flight method and the interferometry based on synthetic wavelengths are the two major categories of methods to achieve absolute distance measurement. The time-of-flight method is limited by the time measurement accuracy, and the dis...

AI Technical Summary

Problems solved by technology

The active homodyne method uses the optical path method to realize the orthogonal bias. In order to reduce the influence of signal fading, it is necessary to add a phase shifter to the interferometer for feedback control so that the interferometer works at the orthogonal operating point. This method The dynamic range is small, and the initial phase drift caused by the working environment affects its low-frequency demodulation characteristics; the passive homodyne method uses a circuit method to achieve quadrature bias, and its representative is the 3×3 coupler method, which does not need to be added to the interferometer phase shifter, but the random phase fading of the interferometer causes random fluctuations in the signal-to-noise ratio of the output signal, and even the signal is completely blanked

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