Laser ranging method and laser ranging device utilizing semi-continuous square wave modulation and flight time measurement

Abstract

The invention discloses a laser ranging method and a laser ranging device utilizing semi-continuous square wave modulation and flight time measurement. The laser ranging method comprises the steps of transmitting a laser signal of which the light strength is modulated by a continuous periodic square wave, receiving an echo optical signal which is reflected by an object, and converting the echo optical signal to an electric signal by means of a photoelectric detector, filtering a low-frequency component through high-pass filtering and moving a voltage middle-position point which is modulated by a square wave to a zero point for settling interference of echo amplitude change to ranging, then inputting the signal into a voltage comparison module for obtaining a plurality of turning signals, measuring a time difference between ranging starting and each turning signal, correcting each time difference according to a square wave signal period for obtaining a plurality of measurement results on flight time of the square wave optical signal, and obtaining accurate distance information after averaging. The laser ranging method has advantages of no measurement range limitation, high ranging speed, easy realization, etc. Performance advantages of a laser in square wave modulation can be sufficiently utilized for constructing a laser ranging system with high performance and multiple channels.

Description

Technical field: [0001] The invention relates to the field of laser ranging signal processing, in particular to a laser ranging method and system based on semi-continuous square wave modulation and time-of-flight measurement. Background technique: [0002] Laser ranging is a major aspect of the application of laser technology. Due to the advantages of high coherence, directivity, and monochromaticity of laser, the laser ranging system can realize long-distance and high-precision ranging functions. The laser ranging system is mainly divided into two types: pulsed light ranging and continuous light ranging. The latter mostly modulates the continuously emitted optical signal and extracts the distance information from the collected echo signal. In the continuous light modulation laser ranging system, higher modulation frequency and laser power can effectively improve the ranging accuracy and ranging speed, but limited by the existing laser technology, the sinusoidally modulated ...

AI Technical Summary

Problems solved by technology

[0003] One of the existing methods is to use a sampling frequency much higher than the modulation frequency of the square wave to sample the echo signal and obtain its multiple high-order harmonics through Fourier transform as described in the literature [1], and calculate the fundamental wave and The phase information of the harmonics is then spliced ​​into the final distance measurement result. However, this method requires a sampling rate dozens of times higher than the modulation frequency of the square wave to obtain high-order harmonic components, and it is difficult to apply to the high fundamental frequency of the square wave itself. occasion

[0004] Another method is to use the same square wave signal as the laser output modulation signal and the gating enable signal of the integral echo detector proposed in literature [2] to obtain the integral value output that changes with the target distance, and use multiple Phase-shifting measurement solves the problem of distance uncertainty, but in principle, this method requires the echo signal and the gating signal to be close to the ideal square wave to achieve high ranging accuracy, and the rise time of the echo signal is strict when the modulation frequency is high

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