A Femtosecond Laser Frequency Comb Pulse Chirp Interferometric Ranging Method and Ranging System

Abstract

The invention discloses a femtosecond laser frequency comb pulse chirp interferometry ranging method and a ranging system. The ranging system comprises a femtosecond laser frequency comb and a Michelson interference system. The light emitted by the femtosecond laser frequency comb is incident to a beam splitter, the light transmitted by the beam splitter is emitted to a first reflecting mirror, and the light reflected by the first reflecting mirror is returned to the beam splitter; the light reflected by the beam splitter is emitted to a first raster, the diffraction light passing through the first raster is incident to a second raster, the diffraction light passing through the second raster is incident to a second reflecting mirror, and the reflected light passing through the second reflecting mirror passes through the second raster and the first raster in order to return to the beam splitter. In the process, chirp is generated to optical pulse, and the center frequency of the optical pulse deviates. The reflected light passing through the first reflecting mirror and the reflected light passing through the second reflecting mirror are combined at the beam splitter, the interference signals of the two light beams are detected and received by a spectrometer, thereby completing range measurement. The ranging method provided by the invention is simple and reliable, has the advantage of high precision, and can be applied in absolute distance measurement.

Description

technical field [0001] The invention relates to a distance measurement method and a distance measurement system, in particular to a femtosecond laser frequency comb pulse chirp interference distance measurement method and a distance measurement system suitable for absolute distance measurement. Background technique [0002] A femtosecond laser frequency comb is a device that locks the repetition rate and phase shift frequency of a femtosecond pulsed laser with a frequency reference source. In the time domain, the optical frequency comb is a continuous pulse sequence (the pulse width is several femtoseconds); in the frequency domain, the optical frequency comb is a longitudinal mode arranged at equal intervals, and the frequency interval between adjacent spectral lines is equal to the repetition frequency of the femtosecond laser. The spectral range covered by the spectral lines is tens of nanometers, and the shape resembles the teeth of a comb, so it is also called "optical ...

AI Technical Summary

Problems solved by technology

First of all, due to the introduction of the filter, the different width of the filter will affect the ranging result, making the ranging result not unique; secondly, when the measured distance is small, the distance between the three peaks is too close in the pseudo-time domain to fail. to achieve accurate filtering; moreover, L pp -L and L pp The spectral interference fringes of +L are identical, making it impossible to distinguish between positive and negative shifts

These are the three limitations of traditional spectral interference-based methods

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