CN-122017872-A - Laser radar double-pulse laser energy high-precision detection device

CN122017872ACN 122017872 ACN122017872 ACN 122017872ACN-122017872-A

Abstract

The device is suitable for an Integral Path Differential Absorption (IPDA) laser radar double-pulse laser energy high-precision detection device, can realize high-precision real-time monitoring of laser energy, and meets the strict precision requirement of the IPDA laser radar on energy monitoring. The device comprises a laser emitting module, a spectroscope, a speckle suppression module, an attenuator, a rough diffuse scattering body, a rotating motor with adjustable rotating speed, a receiving module, an integrating sphere, a delay optical fiber, a collimating mirror, a receiving telescope, a photoelectric detector and a data acquisition and processing module. According to the invention, the rotating rough diffuse scattering body is used for inhibiting speckle errors, the integrating sphere is combined for eliminating the influence of laser pointing change, and the same detector is used for receiving energy signals of the detection light beam and the monitoring light beam, so that the accuracy of energy monitoring is improved, and the measurement error of the IPDA laser radar is reduced.

Inventors

CHEN WEIBIAO
Fan Chuncan
LIU JIQIAO
ZHU XIAOPENG
LI RUI
ZHOU GUOWEI
WAN YUAN
ZANG HUAGUO
ZHANG XIAOXI

Assignees

中国科学院上海光学精密机械研究所

Dates

Publication Date: 20260512
Application Date: 20260415

Claims (10)

1. The utility model provides a laser radar dipulse laser energy high accuracy detection device which characterized in that includes: The laser emission module comprises a dual-wavelength pulse laser (1) and a spectroscope (2), wherein the spectroscope (2) is arranged on an emergent light path of the dual-wavelength pulse laser (1) to divide an incident laser pulse into two paths, one path is a detection light beam, the other path is a monitoring light beam, and the detection light beam is directly emitted to the atmosphere; The speckle suppression module is characterized in that an attenuator (3), a rough diffuse scattering body (4) and a rotating motor (5) with adjustable rotating speed are sequentially arranged along the propagation direction of the monitoring light beam, the rough diffuse scattering body (4) is fixedly arranged on a rotating shaft of the rotating motor (5), the monitoring light beam firstly attenuates energy through the attenuator (3) and then enters the surface of the rough diffuse scattering body (4) driven to rotate by the rotating motor (5), and the rotating speed of the rough diffuse scattering body (4) is changed by adjusting the rotating speed of the rotating motor (5) so as to suppress laser speckles; The receiving module comprises an integrating sphere (6), a delay optical fiber (7), a collimating mirror (8), a receiving telescope (9) and a photoelectric detector (10), wherein an incident port of the integrating sphere (6) is opposite to an emergent surface of the rough diffuse scattering body (4) and is used for receiving a monitoring beam after speckle suppression, the emergent port of the integrating sphere (6) is coupled to an input end of the delay optical fiber (7), an output end of the delay optical fiber (7) is connected with the collimating mirror (8), an emergent light path of the collimating mirror (8) is aligned with a photosensitive surface of the photoelectric detector (10), and an optical path output end of the receiving telescope (9) is also aligned with the same photosensitive surface of the photoelectric detector (10) and is used for receiving a detection beam echo signal after hard target reflection; And the input end of the data acquisition and processing module (11) is electrically connected with the output end of the photoelectric detector (10) and is used for acquiring and processing monitoring beam signals and detecting beam echo signals.
2. The laser radar double-pulse laser energy high-precision detection device according to claim 1 is characterized in that the rough diffuse scattering body (4) is frosted glass, a ceramic scattering sheet or a metal diffuse reflection plate, the surface roughness of the rough diffuse scattering body is optimally selected according to the wavelength and the energy monitoring precision requirement of the double-wavelength pulse laser (1), the rotating motor (5) is an automatic rotating platform or a direct current brushless motor with continuously adjustable rotating speed, the rotating speed adjusting range covers a rotating speed interval with optimal speckle suppression effect, so that the surface linear speed of the rough diffuse scattering body (4) is larger than the movement correlation length of a speckle pattern in one laser pulse period, and the energy standard deviation caused by speckle is reduced to be below 0.5%.
3. The laser radar double-pulse laser energy high-precision detection device according to claim 1, wherein the inner wall of the integrating sphere (6) is made of high-diffuse reflection material, a preset gap or light path alignment is kept between an incidence port of the integrating sphere and an emergent surface of the rough diffuse scattering body (4), the high-precision detection device is used for receiving a monitoring light beam after speckle suppression, influences of directional jitter and energy distribution nonuniformity of the monitoring light beam on energy measurement are eliminated through multiple diffuse reflection inside the integrating sphere, and emergent light of the integrating sphere (6) is lambertian uniform scattered light.
4. The laser radar double pulse laser energy high precision detection device according to claim 1, characterized in that the delay fiber (7) is a multimode fiber, the length of which is set according to the detection distance of the detection beam, so that the monitoring beam generated by the same laser pulse is separated in time from the detection beam echo signal, and the monitoring beam signal reaches the same photosensitive surface of the photoelectric detector (10) before the detection beam echo signal, thereby realizing single detector time sharing reception.
5. The lidar double-pulse laser energy high-precision detection device according to claim 1, characterized in that the photodetector (10) is an Avalanche Photodiode (APD), a photomultiplier tube (PMT) or a PIN photodiode, the photosensitive surfaces of which are located on the outgoing light path of the collimating mirror (8) and the outgoing light path of the receiving telescope (9) at the same time, and the monitoring beam and the detection beam echo signal do not overlap in time, so as to avoid signal crosstalk.
6. The laser radar double-pulse laser energy high-precision detection device according to claim 1, wherein the data acquisition and processing module (11) comprises a high-speed data acquisition card and an FPGA embedded processing board, a control output end of the FPGA embedded processing board is connected with a trigger input end of the double-wavelength pulse laser (1) and used for controlling laser emission time sequence, the FPGA embedded processing board also synchronously triggers the high-speed data acquisition card to record a voltage waveform output by the photoelectric detector (10), and a peak extraction algorithm and a normalization energy ratio calculation unit are embedded in the FPGA embedded processing board and used for extracting a monitoring pulse peak value (P on0 、P off0 ) and an echo pulse peak value (P on 、P off ) from the waveform and calculating a normalization energy ratio so as to correct gas concentration inversion of the IPDA laser radar.
7. The laser radar double-pulse laser energy high-precision detection device according to claim 1, wherein two wavelengths output by the double-wavelength pulse laser (1) are respectively positioned on an absorption line and an absorption line of target gas and are used for detecting the atmospheric temperature chamber gas concentration of the integral path differential absorption laser radar, and the spectroscope (2) has a spectroscope ratio of 99:1, 98:2 or 95:5, so that most laser energy is used as a detection beam, and a small part of energy is used as a monitoring beam.
8. The laser radar double pulse laser energy high precision detecting device according to claim 1, wherein the receiving telescope (9) is a Cassegrain Lin Fanshe telescope, and an optical axis of the telescope is parallel or coaxial with an emission optical axis of the detecting beam, and is used for collecting echo signals after diffuse reflection of a hard target and converging the echo signals to a photosensitive surface of the photoelectric detector (10).
9. The laser radar double pulse laser energy high precision detecting device according to claim 1, wherein the attenuator (3) is a neutral density attenuator or an adjustable attenuator, and the attenuation multiple is set according to the initial energy of the monitoring beam and the linear response range of the photodetector (10) so as to avoid saturation of the photodetector and ensure that the photodetector works in a linear region.
10. The laser radar double-pulse laser energy high-precision detection device according to claim 1, wherein the speckle suppression module, the integrating sphere (6) and the photoelectric detector (10) form a single-detector time-sharing receiving framework in a coordinated manner, the speckle suppression module is used for suppressing speckle noise of a monitoring beam, the integrating sphere (6) is used for eliminating directional jitter and energy maldistribution of the monitoring beam, and the photoelectric detector (10) receives a monitoring beam signal and a detection beam echo signal in a time-sharing manner, so that the problem of energy measurement errors caused by speckle effects, directional jitter and double-detector differences is solved.

Description

Laser radar double-pulse laser energy high-precision detection device Technical Field The invention belongs to the technical field of laser radar energy monitoring, and particularly relates to a laser energy real-time monitoring and correcting device suitable for Integrated Path Differential Absorption (IPDA) laser radar double-pulse laser energy high-precision detection, which can be used for detecting the gas concentration of an atmospheric temperature chamber. Background Integral Path Differential Absorption (IPDA) lidar is currently a device for high-precision detection of atmospheric chamber gas concentration, and the measurement precision thereof depends on the calculation of the energy ratio of laser emission pulse to echo pulse. Since the emitted pulse directly enters the atmosphere and cannot be directly measured, the prior art generally adopts a spectroscopic monitoring scheme, namely, the emitted pulse is divided into a detection beam (for atmospheric detection) and a monitoring beam (for energy monitoring), and the initial energy change of the detection beam is indirectly reflected through the energy jitter of the monitoring beam. The existing energy monitoring technology has two key problems, namely, speckle effect influence, energy signal jitter is caused by interference of coherent light to form speckle patterns with light and dark alternation after monitoring light beams are scattered by an integrating sphere, monitoring precision is reduced, and the difference problem of two detectors is solved, wherein part of the schemes adopt independent detectors to respectively receive echo signals and monitoring signals, and extra errors are introduced due to different ageing degrees of the detectors in long-term operation. In addition, the roughness and the rotating speed of the existing diffuser are not subjected to system optimization, the speckle suppression effect is limited, and the high-precision requirement of high-precision detection on energy monitoring is difficult to meet. In view of the foregoing, there is a need to design a laser energy detection device that can effectively suppress speckle error, eliminate the influence of laser pointing shake, avoid the difference between two detectors, and has high stability, so as to improve the overall measurement accuracy and long-term reliability of the IPDA laser radar. Disclosure of Invention The invention aims to solve the technical problems of large monitoring error and the like caused by speckle effect in the existing IPDA laser radar energy detection device, provides a high-stability and high-precision energy monitoring device, and meets the energy monitoring requirement of IPDA laser radar greenhouse gas concentration detection. The technical scheme of the invention is as follows: the utility model provides a laser radar dipulse laser energy high accuracy detection device which characterized in that includes: The laser emission module comprises a dual-wavelength pulse laser and a spectroscope, wherein the spectroscope is arranged on an emergent light path of the dual-wavelength pulse laser, the incident laser pulse is divided into two paths, one path is a detection light beam, the detection light beam is directly emitted to the atmosphere, and the other path is a monitoring light beam; The speckle suppression module is used for sequentially arranging an attenuator, a rough diffuse scattering body and a rotating motor with adjustable rotating speed along the propagation direction of the monitoring light beam; the rough diffuse scattering body is fixedly arranged on a rotating shaft of the rotating motor, the monitoring light beam firstly attenuates energy through the attenuator and then enters the surface of the rough diffuse scattering body driven by the rotating motor to rotate, and the rotating speed of the rough diffuse scattering body is changed by adjusting the rotating speed of the rotating motor so as to inhibit laser speckles; The receiving module comprises an integrating sphere, a delay optical fiber, a collimating mirror, a receiving telescope and a photoelectric detector; the entrance port of the integrating sphere is opposite to the emergent surface of the rough diffuse scattering body and is used for receiving the monitoring light beam after speckle suppression; the exit port of the integrating sphere is coupled to the input end of the delay optical fiber, the output end of the delay optical fiber is connected with the collimating mirror, and the exit light path of the collimating mirror is aligned with the photosensitive surface of the photoelectric detector; the light path output end of the receiving telescope is also aligned to the same photosensitive surface of the photoelectric detector and is used for receiving the echo signal of the detection light beam reflected by the hard target; And the input end of the data acquisition and processing module is electrically connected with the output end of the photoelectric detector