Method and device for measuring frequency scanning absolute distance based on femtosecond optical frequency comb

Abstract

The invention relates to a device for measuring a frequency scanning absolute distance based on a femtosecond optical frequency comb and a method for measuring the absolute distance based on the device. The device comprises: a tunable laser (1), a polarization maintaining fiber system (2), a double-frequency heterodyne interferometer (3) and a system for measuring a laser frequency and an interferometric phase (4); the tunable laser (1) is used for generating single-frequency, single-line polarization laser, and an output laser frequency can be controlled by the working voltage and current ofthe tunable laser; the polarization maintaining fiber system (2) is used for coupling space laser with a polarization maintaining fiber in an unreflected way, and dividing the space laser into three paths of optical signals with equal optical intensity, and keeping an output laser polarization direction the same as an input laser polarization direction; the double-frequency heterodyne interferometer (3) is used for converting single-frequency laser into double-frequency orthogonal polarization laser, and converting distance information to be measured into phase information of a laser beat signal; and the system for measuring the laser frequency and the interferometric phase (4) is used for precisely measuring and locking and inputting the frequency of the laser, and measuring a phase different between the two paths of alternating current signals.

Description

technical field [0001] The present invention relates to an absolute distance measurement method and device, in particular to a femtosecond optical frequency comb-based frequency scanning absolute distance measurement method and device. Background technique [0002] Laser interference distance measurement is to obtain the distance difference between the measurement optical path and the reference optical path by detecting the phase difference between the reference optical path and the measurement optical path and according to the corresponding relationship between the interference wavefront phase and the optical path. The phase difference of the reference optical path and the measuring optical path changes by 2π every time the optical distance of the optical path changes by one interference wavelength. The phase difference between the reference light path and the measurement light path includes an integer part and a fractional part of the phase, that is, the number of whole cy...

AI Technical Summary

Problems solved by technology

However, the Fabry-Perot cavity can only use the principle of multi-beam interference to measure the laser frequency indirectly, and its measurement accuracy depends on the physical cavity length stability and fineness of the Fabry-Perot cavity

In addition, the operating frequency of the tunable laser has not been established with the current metrology standard, and this method fails to meet the requirements of metrology that the measurement should be traceable

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