Fabry-Perot interference absolute distance measurement method based on femtosecond optical frequency comb and device thereof

Abstract

The invention relates to a Fabry-Perot interference absolute distance measurement method based on a femtosecond optical frequency comb and a device thereof. Two tunable lasers with frequency capable of being tuned within a large range and free of mode skip are simultaneously adopted, the optical wavelengths of the two lasers are respectively locked on two transmission peaks at a distance of N free spectral ranges of a to-be-detected Fabry-Perot cavity with the cavity length located in a vacuum vibration isolation cavity by utilizing the Pound-Drever-Hall (PDH) method, a wavemeter and an optical frequency comb system are used to respectively measure absolute frequency of two beams of laser, and then the free spectral ranges of the to-be-detected Fabry-Perot cavity are obtained. The cavity length of the to-be-detected Fabry-Perot cavity is obtained by means of the relationship between the to-be-detected cavity length and the free spectral ranges, frequency of the two tunable lasers can be tuned within a large range and free of mode skip, and measurement range is increased. Meanwhile, frequency of the two lasers is locked, and measurement speed can be increased. The optical frequencycomb system for measuring the frequency of the two lasers enables recurrence frequency and off-set frequency to be traced to the source of microwave frequency standard so that measurement results canhave traceability.

Description

technical field [0001] The invention belongs to the field of absolute distance measurement, in particular to a femtosecond optical frequency comb-based F-Per interference absolute distance measurement method and device. Background technique [0002] At present, among the seven basic quantities of the International System of Units, the kilogram is the only unit defined by the physical benchmark. Since the physical benchmark will drift with time and environmental changes, it is unstable and irreproducible. Therefore, the natural benchmark is used Redefining the kilogram instead of the physical basis has become an important task in the field of metrology. Planck's constant h can precisely define the mass benchmark, which is a relatively common method in the world at present. For this reason, the NIM of the Chinese Academy of Metrology and Sciences proposed an energy balance scheme for measuring mutual inductance in the displacement mode of the movable coil. The basic principle...

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Problems solved by technology

However, limited by the frequency tuning range of the laser frequency shifter, the measurement range of this method is small

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