A femtosecond laser ranging system based on beat frequency method between modes

Abstract

The invention relates to a femtosecond laser intermode beat frequency method ranging system. The ranging system is characterized in that the ranging system comprises a femtosecond laser frequency comb, an acoustooptic modulator, a first beam splitter prism, a second beam splitter prism, a first mechanical shutter, a second mechanical shutter, a first reflection mirror, a first fiber coupling mirror, a second fiber coupling mirror, a beam expander, a corner reflector, a first photodetector, a second photodetector and a signal processing system. According to the invention, the acoustooptic modulator is used to realize wavelength synthesis; the measuring range of a femtosecond laser intermode beat frequency method is enlarged; changing the resonant cavity length to adjust the repetition frequency of a femtosecond laser is not needed in a measurement process; due to the fact that the acoustooptic modulator is an electronic control device, a acoustooptic modulator controller has the advantages of simple structure, easy operation and short device response time compared with a mechanical delay line which adjusts the resonant cavity length of the laser; time required for single measurement can be greatly reduced; measurement steps are simplified; and fast and convenient measurement is realized.

Description

technical field [0001] The invention relates to a femtosecond laser absolute distance measurement system, in particular to a femtosecond laser intermode beat frequency method distance measurement system. Background technique [0002] Traditional laser ranging methods include time-of-flight, interferometry, and single-wavelength phase methods. The time-of-flight method measures the distance of the target by measuring the round-trip flight time of light between the light source and the target. Due to the extremely fast speed of light, the round-trip flight time of light is short and the measurement accuracy is limited, resulting in low ranging accuracy of this method; the interferometric method can Realize the measurement accuracy of sub-optical wavelength level, but the unambiguous distance is also at the wavelength level. During the measurement process, guide rails must be set up for uninterrupted incremental measurement, and absolute distance measurement cannot be realized;...

AI Technical Summary

Problems solved by technology

However, this method requires manual or electronic adjustment of the delay line length of the femtosecond laser resonator, which involves mechanical adjustment. The structure of the adjustment system is relatively complicated, and the adjustment takes a long time, resulting in a long measurement time, which is not conducive to fast real-time measurement; and the adjustment process may affect the stability of the laser

In addition, some commercial femtosecond laser frequency comb light sources do not have the function of adjusting the laser resonator in a wide range, so it is impossible to realize the synthetic wavelength method to expand the distance measurement range of the femtosecond laser intermode beat frequency method

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