CN-119471644-B - Laser scanning system and nonlinear correction method

CN119471644BCN 119471644 BCN119471644 BCN 119471644BCN-119471644-B

Abstract

The embodiment of the invention discloses a laser scanning system and a nonlinear correction method, wherein the system comprises a laser emission and control module, a scanning device, a receiving device and a signal processing module, wherein the system can obtain an initial first beat signal, remove a direct current signal and a high-frequency signal in the first beat signal to obtain a second beat signal from which the direct current signal and the high-frequency signal are removed, calculate the target voltage of the second beat signal according to the input voltage corresponding to the first beat signal and the instantaneous frequency of the second beat signal, output a new beat signal based on the target voltage to obtain a target beat signal with the frequency of a preset target frequency, and the target frequency and time are in a linear relation. By controlling the frequency of the input voltage control beat signal, the output beat signal is realized in a linear relationship between frequency and time.

Inventors

ZHANG JUN
DING HANFENG
CHEN HAO
LIANG PANPAN

Assignees

桂林电子科技大学

Dates

Publication Date: 20260508
Application Date: 20241023

Claims (10)

1. A laser scanning system, characterized in that the system comprises a laser emission and control module, a scanning device, a receiving device and a signal processing module; the laser emission and control module is used for obtaining target waveform data and outputting a target waveform signal corresponding to the target waveform data into an optical signal, wherein the target waveform data is waveform data corresponding to a preset input voltage; The scanning device is connected with the laser emission and control module and is used for emitting optical signals to a target irradiation object to form emitted light; the receiving device is connected with the scanning device and is used for receiving echo signals, calculating the difference value between the transmitting signals and the echo signals and obtaining beat signals; The signal processing device is connected with the receiving device and is used for receiving the beat signal, obtaining an initial first beat signal, obtaining a spectrogram of the first beat signal, removing a direct current signal and a high-frequency signal in the first beat signal based on the spectrogram, obtaining a second beat signal after the direct current signal and the high-frequency signal are removed; The signal processing device is connected with the laser emission and control module and is used for outputting a target voltage to the laser emission and control module; the signal processing device is used for outputting a target beat signal based on the target voltage to obtain a linear time-frequency curve, wherein the target beat signal is a beat signal with the frequency being a preset target frequency, and the target frequency and time are in a linear relation.
2. The system of claim 1, wherein the laser emission and control module comprises a waveform generator comprising an FPGA; The FPGA is internally provided with a phase accumulator, and is used for storing preset waveform data, establishing a corresponding relation between the waveform data and a corresponding reading address to obtain a lookup table, and acquiring the waveform data corresponding to the reading address from the lookup table according to the reading address output by the phase accumulator to obtain target waveform data.
3. The system of claim 1, wherein the laser emission and control module 101 further comprises a laser, wherein the waveform generator further comprises a digital-to-analog converter, a filter, and a post-amplifier; The digital-to-analog converter is connected with the FPGA, the FPGA is used for outputting the target waveform data to the digital-to-analog converter in the form of initial waveform signals, and the digital-to-analog converter is used for receiving the initial waveform signals output by the FPGA, converting the initial waveform signals into analog signals and outputting the analog signals; The filter is connected with the digital-to-analog converter and is used for receiving the analog signal output by the digital-to-analog converter, performing smoothing filter processing on the analog signal to obtain a target analog signal after the smoothing filter processing and outputting the target analog signal; the post-stage amplifier is connected with the filter and is used for receiving the target analog signal output by the filter, performing voltage amplification processing on the target analog signal to obtain a final target signal and outputting the target signal; the laser is connected with the post-stage amplifier and is used for receiving a target signal and outputting an optical signal.
4. The system of claim 2, wherein the laser emission and control module is further configured to control deflection of a scanning device configured to emit the light signal at the deflected current angle to the target illumination object to form the emitted light.
5. The system of claim 4, wherein the scanning device comprises a transverse X-axis scanning device and a longitudinal Y-axis scanning device; the transverse X-axis scanning device and the longitudinal Y-axis scanning device are respectively connected with the FPGA; the FPGA is used for controlling the transverse X-axis scanning device to deflect a first fixed angle for a plurality of times, and the scanning device is used for respectively emitting light signals based on the current angle after the transverse X-axis scanning device deflects the first fixed angle each time to form emitted light so as to transversely scan the target irradiation object; The FPGA is further used for controlling the longitudinal Y-axis scanning device to deflect a second fixed angle after the scanning device transversely scans the target irradiation object, and returning to execute the step of controlling the transverse X-axis scanning device to deflect a first fixed angle for a plurality of times so as to control the scanning device to deflect the second fixed angle after the scanning device transversely scans the target irradiation object, and transmitting optical signals based on the current angle after each time of deflecting the first fixed angle by the transverse X-axis scanning device respectively to form transmitting light until the target irradiation object is transversely scanned; If the target irradiation object is not scanned, the FPGA is further used for returning to the step of controlling the longitudinal Y-axis scanning device to deflect a second fixed angle after the scanning device transversely scans the target irradiation object until the target irradiation object is scanned.
6. The system of claim 1, wherein the signal processing module is configured to determine whether an instantaneous frequency of the second beat signal reaches a preset target frequency, output the second beat signal if the instantaneous frequency of the second beat signal reaches the preset target frequency, obtain a target beat signal with a frequency equal to the preset target frequency, calculate an initial voltage according to the instantaneous frequency and the input voltage if the instantaneous frequency of the second beat signal does not reach the preset target frequency, obtain a third beat signal obtained by taking the initial voltage as an input voltage of the laser emission and control module, remove a dc current signal and a high frequency signal in the third beat signal based on a frequency of the third beat signal, obtain a fourth beat signal from which the dc current signal and the high frequency signal are removed, and return to perform the step of determining whether the instantaneous frequency of the second beat signal reaches the preset target frequency by taking the third beat signal as a first beat signal and the fourth beat signal.
7. A method of non-linear correction, the method being applied to the system of claim 1, the method comprising: Acquiring an initial first beat signal, acquiring a spectrogram of the first beat signal, and removing a direct current signal and a high-frequency signal in the first beat signal based on the spectrogram to obtain a second beat signal from which the direct current signal and the high-frequency signal are removed; Obtaining input voltage corresponding to the first beat signal, obtaining the instantaneous frequency of the second beat signal, judging whether the instantaneous frequency of the second beat signal reaches a preset target frequency, outputting the second beat signal to obtain a target beat signal with the frequency being the preset target frequency if the instantaneous frequency of the second beat signal reaches the preset target frequency, calculating target voltage according to the instantaneous frequency and the input voltage if the frequency of the second beat signal does not reach the preset target frequency, outputting a new beat signal based on the target voltage to obtain the target beat signal with the frequency being the preset target frequency, wherein the target frequency and time are in a linear relation.
8. The method of claim 7, wherein calculating a target voltage from the instantaneous frequency and the input voltage, outputting a new beat signal based on the target voltage, and obtaining a target beat signal with a frequency that is a preset target frequency, comprises: Calculating an initial voltage according to the instantaneous frequency and the input voltage, obtaining a third beat signal obtained by taking the initial voltage as the input voltage of the laser emission and control module, and removing a direct current signal and a high frequency signal in the third beat signal based on a spectrogram of the third beat signal to obtain a fourth beat signal from which the direct current signal and the high frequency signal are removed; and returning to the step of judging whether the instantaneous frequency of the second beat signal reaches a preset target frequency by taking the third beat signal as a first beat signal and taking the fourth beat signal as a second beat signal.
9. The method of claim 7, wherein the removing the dc current signal and the high frequency signal from the first beat signal based on the spectrogram comprises: and searching a direct current signal reaching a first frequency and a high frequency signal reaching a second frequency in the first beat signal based on the spectrogram, and filtering the direct current signal with the first frequency and the high frequency signal with the second frequency by adopting a band-pass filter.
10. The method of claim 8, wherein the calculation formula for calculating the initial voltage from the instantaneous frequency and the input voltage is: Wherein U 2 represents an initial voltage, a represents a frequency modulation rate, r represents a transmission delay, f represents an instantaneous frequency of the second beat signal, and U 1 represents an input voltage.

Description

Laser scanning system and nonlinear correction method Technical Field The present invention relates to the field of laser signal processing technologies, and in particular, to a laser scanning system and a nonlinear correction method. Background Ranging can be performed by a laser, specifically, a difference between the emitted light (emitted signal) and the reflected light (echo signal) of the target irradiation object by the laser is calculated to obtain a beat signal, and the distance of the target irradiation object can be calculated according to the frequency of the beat signal. Ideally, the frequency and time of the beat signal output by the laser are linear, and then affected by external factors (such as temperature) can cause the frequency and time of the beat signal to be nonlinear, so that the ranging accuracy can be reduced. In the prior art, the frequency of the beat signal can be adjusted by a current tuning mode, but the relation between the injection current and the output wavelength is theoretically analyzed to be a linear relation, and the laser wavelength is inversely proportional to the frequency, so that even if the linear current is injected, the linear frequency modulation laser cannot be obtained, and on the other hand, the influence on the output frequency is caused along with the change of temperature in the current tuning process. Therefore, a method is required to achieve correction of the frequency of the beat signal so that the frequency of the output beat signal is linear with time. Disclosure of Invention The invention mainly aims to provide a laser scanning system, a nonlinear correction method, computer equipment and a storage medium, which can solve the problem of nonlinearity of frequency and time of a beat signal in the prior art. To achieve the above object, a first aspect of the present invention provides a laser scanning system, the system including a laser emission and control module, a scanning device, a receiving device, and a signal processing module; the laser emission and control module is used for obtaining target waveform data and outputting a target waveform signal corresponding to the target waveform data into an optical signal, wherein the target waveform data is waveform data corresponding to a preset input voltage; The scanning device is connected with the laser emission and control module and is used for emitting optical signals to a target irradiation object to form emitted light; the receiving device is connected with the scanning device and is used for receiving echo signals, calculating the difference value between the transmitting signals and the echo signals and obtaining beat signals; The signal processing device is connected with the receiving device and is used for receiving the beat signal, obtaining an initial first beat signal, obtaining a spectrogram of the first beat signal, removing a direct current signal and a high-frequency signal in the first beat signal based on the spectrogram, obtaining a second beat signal after the direct current signal and the high-frequency signal are removed; The signal processing device is connected with the laser emission and control module and is used for outputting a target voltage to the laser emission and control module; the signal processing device is used for outputting a target beat signal based on the target voltage to obtain a linear time-frequency curve, wherein the target beat signal is a beat signal with the frequency being a preset target frequency, and the target frequency and time are in a linear relation. With reference to the first aspect, in one possible implementation manner, the laser emission and control module comprises a waveform generator; The FPGA is internally provided with a phase accumulator, and is used for storing preset waveform data, establishing a corresponding relation between the waveform data and a corresponding reading address to obtain a lookup table, and acquiring the waveform data corresponding to the reading address from the lookup table according to the reading address output by the phase accumulator to obtain target waveform data. With reference to the first aspect, in one possible implementation manner, the laser emission and control module 101 further includes a laser, the waveform generator further includes a digital-to-analog converter, a filter, and a post-amplifier; The digital-to-analog converter is connected with the FPGA, the FPGA is used for outputting the target waveform data to the digital-to-analog converter in the form of initial waveform signals, and the digital-to-analog converter is used for receiving the initial waveform signals output by the FPGA, converting the initial waveform signals into analog signals and outputting the analog signals; The filter is connected with the digital-to-analog converter and is used for receiving the analog signal output by the digital-to-analog converter, performing smoothing filter processing on the analog signal to o