Near-field saturation signal attenuation device and method based on acousto-optic modulator

Abstract

The present invention provides a near-field saturation signal attenuation device and method based on an acousto-optic modulator, which can be applied to the field of laser radar technology. The device includes: a laser transmitting module, which is used to transmit an incident pulse laser; a polarization beam splitter prism, which is used to screen the incident pulse laser to obtain a parallel polarized pulse laser; a collection module, which is used to transmit the parallel polarized pulse laser to a target position and collect the echo light signal generated by the target position scattering, wherein the echo light signal includes a near-field saturation signal and a far-field echo signal; an attenuation module, which is used to attenuate the near-field saturation signal collected by the collection module when determining that the echo light signal is a near-field saturation signal, to obtain a target echo light signal; a photoelectric detector, which is used to process the target echo light signal and the far-field echo signal emitted by the attenuation module to obtain target data for analyzing the target position.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and more specifically to a near-field saturation signal attenuation device and method based on an acousto-optic modulator. Background Art

[0002] The structure of laser radar is roughly divided into: optical transmitter, optical receiver and data processing system. The optical transmitter emits a light beam of a certain wavelength to reach the designated target. After a certain physical effect occurs with the designated target, the optical receiver receives the returned echo signal and obtains the electrical signal through the data processing system, and digitizes the electrical signal.

[0003] For most lidars, there are blind spots in near-field detection. The blind spots are mostly formed because the signals in the near field are too strong, causing the detector to be saturated. The data processing system is unable to extract valid information from it, resulting in the extracted information being inaccurate. Summary of the invention

[0004] In view of the above problems, the present invention provides a near-field saturation signal attenuation device and method based on an acousto-optic modulator.

[0005] According to a first aspect of the present invention, a near-field saturation signal attenuation device based on an acousto-optic modulator is provided, comprising: a laser transmitting module, used to transmit an incident pulse laser; a polarization beam splitter prism, used to screen the incident pulse laser emitted by the laser transmitting module to obtain a parallel polarized pulse laser; an acquisition module, used to transmit the parallel polarized pulse laser emitted by the polarization beam splitter prism to a target position, and to acquire an echo light signal generated by scattering from the target position, wherein the echo light signal comprises a near-field saturation signal and a far-field echo signal; an attenuation module, used to attenuate the near-field saturation signal acquired by the acquisition module when determining that the echo light signal is a near-field saturation signal, to obtain a target echo light signal; and a photodetector, used to perform data processing on the target echo light signal and the far-field echo signal emitted by the attenuation module to obtain target data for analyzing the target position.

[0006] According to an embodiment of the present invention, the attenuation module includes: an acousto-optic modulator, which is used to attenuate the near-field saturation signal emitted by the polarization splitter prism to obtain a target echo light signal; an acousto-optic modulator driver, which is connected to the acousto-optic modulator and is used to control the start and stop of the acousto-optic modulator; a signal generator, one end of which is connected to the acousto-optic modulator driver and the other end of which is connected to the laser transmitting module, and is used to generate a control instruction and send it to the acousto-optic modulator driver when it is determined that the echo light signal is a near-field saturation signal.

[0007] According to an embodiment of the present invention, the acquisition module includes: a reflector for adjusting the emission direction of the parallel polarized pulse laser emitted by the polarization splitter prism and the incident direction of the echo light signal; a telescope for transmitting the parallel polarized pulse laser emitted by the reflector to the target position and collecting the echo light signal generated by scattering from the target position.

[0008] According to an embodiment of the present invention, the above-mentioned device further includes: a quarter wave plate, which is arranged between the polarization beam splitter prism and the acquisition module, and is used to adjust the polarization state of the parallel polarized pulse laser and the echo light signal.

[0009] According to an embodiment of the present invention, the above-mentioned device further includes: a narrow-band filter, which is arranged between the polarization beam splitter prism and the attenuation module, and is used to filter the echo light signal to obtain a filtered echo light signal.

[0010] According to an embodiment of the present invention, the above-mentioned device also includes: a beam expander, which is arranged between the laser emission module and the polarization splitter prism, and is used to expand the incident pulsed laser; a coupling lens, which is arranged between the photodetector and the attenuation module, and is used to couple the target echo light signal and the far-field echo signal to the photodetector.

[0011] The second aspect of the present invention provides a near-field saturation signal attenuation method based on an acousto-optic modulator, characterized in that the method includes: using a laser transmitting module to transmit an incident pulse laser; using a polarization splitter prism to screen the incident pulse laser to obtain a parallel polarized pulse laser; emitting the parallel polarized pulse laser to a target position, and collecting an echo light signal generated by scattering from the target position; using a signal generator to determine that the echo light signal is a near-field saturation signal, using an acousto-optic modulator to attenuate the near-field saturation signal to obtain a target echo light signal.

[0012] According to an embodiment of the present invention, the near-field saturation signal is determined based on the following operations: collecting a first time point of an incident pulse laser, the first time point representing the time point when the incident pulse laser completes emission; determining a second time point based on the first time point and a preset time difference, the second time point representing the time point when the near-field saturation signal collection is completed; and determining an echo light signal received earlier than the second time point as a near-field saturation signal.

[0013] According to an embodiment of the present invention, the incident pulse laser includes a first polarization state pulse laser and a second polarization state pulse laser; the incident pulse laser is screened by using a polarization beam splitter prism to obtain a parallel polarized pulse laser, including: using a polarization beam splitter prism to remove the second polarization state pulse laser of the incident pulse laser, and using the first polarization state pulse laser of the incident pulse laser as the parallel polarized pulse laser.

[0014] According to an embodiment of the present invention, the echo light signal includes a first polarization state light signal and a second polarization state light signal; the method also includes: using a polarization beam splitter prism to remove the first polarization state light signal of the echo light signal, and transmitting the second polarization state light signal of the echo light signal to an acousto-optic modulator, wherein the second polarization state light signal is a vertically polarized light signal.

[0015] According to an embodiment of the present invention, the laser transmitting module transmits an incident pulse laser; the polarization beam splitter screens the incident pulse laser to obtain a parallel polarized pulse laser; the acquisition module transmits the parallel polarized pulse laser to the target position, and acquires the echo light signal generated by the target position scattering; the attenuation module attenuates the near-field saturation signal when determining that the echo light signal is a near-field saturation signal to obtain a target echo light signal; the photodetector processes the target echo light signal and the far-field echo signal to obtain target data. Since the attenuation module is used to determine whether the currently received echo light signal is a near-field saturation signal, the near-field saturation signal can be attenuated without affecting the far-field echo signal, thereby avoiding the problem that the signal near the detector is saturated due to being too strong, and the data processing system cannot extract effective information from it, so that the information obtained after processing is more accurate, which is convenient for relevant analysis and processing of the target position. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 A structural block diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to an embodiment of the present invention is shown;

[0018] Figure 2 A schematic diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to an embodiment of the present invention is shown;

[0019] Figure 3 A schematic diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to another embodiment of the present invention is shown;

[0020] Figure 4 A flowchart of a near-field saturation signal attenuation method based on an acousto-optic modulator according to an embodiment of the present invention is shown;

[0021] Figure 5 A timing diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0022] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0023] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0024] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0025] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0026] For most lidars, there are blind spots in near-field detection. The blind spots are mostly formed because the signals in the near field are too strong, causing the detector to be saturated. The data processing system is unable to extract valid information from it, resulting in the extracted information being inaccurate.

[0027] The embodiment of the present invention provides a near-field saturation signal attenuation device based on an acousto-optic modulator, comprising: a laser transmitting module, used to transmit an incident pulse laser; a polarization beam splitter prism, used to screen the incident pulse laser emitted by the laser transmitting module to obtain a parallel polarized pulse laser; a collection module, used to transmit the parallel polarized pulse laser emitted by the polarization beam splitter prism to a target position, and collect an echo light signal generated by scattering at the target position, wherein the echo light signal includes a near-field saturation signal and a far-field echo signal; an attenuation module, one end of which is connected to the laser transmitting module, and is used to attenuate the near-field saturation signal collected by the collection module when determining that the echo light signal is a near-field saturation signal, so as to obtain a target echo light signal; a photoelectric detector, used to perform data processing on the target echo light signal and the far-field echo signal emitted by the attenuation module, so as to obtain target data for analyzing the target position.

[0028] Figure 1 A structural block diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to an embodiment of the present invention is shown.

[0029] According to a first aspect of the present invention, a near-field saturation signal attenuation device based on an acousto-optic modulator is provided, comprising a laser transmitting module 100, a polarization beam splitter prism 200, a collection module 300, an attenuation module 400 and a photodetector 500.

[0030] The laser emitting module 100 is used to emit incident pulsed laser.

[0031] The polarization beam splitter prism 200 is used to screen the incident pulse laser emitted by the laser emission module 100 to obtain parallel polarized pulse laser.

[0032] The acquisition module 300 is used to transmit the parallel polarized pulse laser emitted by the polarization beam splitter prism 200 to the target position and to collect the echo light signal generated by scattering at the target position, wherein the echo light signal includes a near-field saturation signal and a far-field echo signal.

[0033] The attenuation module 400 is used to perform signal attenuation on the near-field saturation signal collected by the collection module 300 to obtain a target echo light signal when it is determined that the echo light signal is a near-field saturation signal.

[0034] The photoelectric detector 500 is used to process the target echo light signal and the far-field echo signal emitted by the attenuation module 400 to obtain target data for analyzing the target position.

[0035] According to an embodiment of the present invention, the laser transmitting module 100 may include a laser for generating laser, wherein the laser may be a tunable seed injection laser. In addition, the laser transmitting module 100 may be provided with a frequency conversion component according to actual needs to output the expected incident pulse laser.

[0036] According to an embodiment of the present invention, the polarization beam splitter prism 200 is an optical element for separating the horizontal polarization and vertical polarization of light. By screening the horizontal polarization and vertical polarization of the incident pulse laser, the parallel polarized pulse laser can pass through the polarization beam splitter prism 200 to enter the collection module 300.

[0037] According to an embodiment of the present invention, the acquisition module 300 is used to receive parallel polarized pulse laser and emit it into the atmosphere. When the parallel polarized pulse laser reaches the target position, it generates scattering at the target position to obtain an echo light signal, which is received by the acquisition module 300.

[0038] According to an embodiment of the present invention, the target location may be any object in the atmosphere.

[0039] According to the embodiment of the present invention, the attenuation module 400 can determine whether the echo light signal is a near-field saturation signal according to the emission time of the incident pulse laser, so as to attenuate the near-field saturation signal without affecting the far-field echo signal.

[0040] According to an embodiment of the present invention, the photodetector 500 is used to perform data processing on the received target echo optical signal and the far-field echo signal. Those skilled in the art may adjust the configuration of the photodetector 500 according to actual data processing requirements. For example, in a wind laser radar, the photodetector 500 may be replaced with a Fabry-Perot etalon (FP etalon) and two photodetectors 500.

[0041] According to an embodiment of the present invention, the laser transmitting module 100 transmits an incident pulse laser; the polarization beam splitter prism 200 screens the incident pulse laser to obtain a parallel polarized pulse laser; the acquisition module 300 transmits the parallel polarized pulse laser to the target position and collects the echo light signal generated by the target position scattering; the attenuation module 400 attenuates the near-field saturation signal when determining that the echo light signal is a near-field saturation signal to obtain a target echo light signal; the photodetector 500 processes the target echo light signal and the far-field echo signal to obtain target data. Since the attenuation module 400 is used to determine whether the currently received echo light signal is a near-field saturation signal, the near-field saturation signal can be attenuated without affecting the far-field echo signal, thereby avoiding the problem that the signal near the detector is saturated due to being too strong, and the data processing system cannot extract effective information from it, so that the information obtained after processing is more accurate, which is convenient for relevant analysis and processing of the target position.

[0042] Figure 2 A schematic diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to an embodiment of the present invention is shown.

[0043] According to an embodiment of the present invention, the attenuation module 400 includes an AOM 410 , an AOM driver 420 , and a signal generator 430 .

[0044] The acousto-optic modulator 410 is used to attenuate the near-field saturation signal emitted by the polarization beam splitter prism 200 to obtain a target echo optical signal.

[0045] The AOM driver 420 is connected to the AOM 410 and is used to control the start and stop of the AOM 410.

[0046] The signal generator 430 is connected to the AOM driver 420 at one end and to the laser transmitting module 100 at the other end, and is used to generate a control instruction and send it to the AOM driver 420 when the echo optical signal is determined to be a near-field saturation signal.

[0047] According to an embodiment of the present invention, the acousto-optic modulator 410 (AOM) can be a device that controls the power of the laser beam through an electrical drive signal. The AOM is responsible for attenuating the near-field saturation signal in the echo optical signal, making the near-field saturation signal a usable signal, thereby shortening the blind area or even achieving no blind area. In addition, the two ends of the AOM are optical fiber-type configurations, using optical fiber to transmit signals with the front and back ends, and can receive most of the signal energy without too much optical adjustment, which is convenient for installation and debugging.

[0048] According to an embodiment of the present invention, the AOM driver 420 is used to receive a control signal to control the start and stop of the AOM.

[0049] According to an embodiment of the present invention, the signal generator 430 is responsible for controlling the timing synchronization between the AOM and the laser transmitting module 100, so as to determine whether the currently received echo light signal is a near-field saturation signal according to the time information of the incident pulse laser emitted by the laser transmitting module 100, and when it is determined that the echo light signal is a near-field saturation signal, a control instruction is generated and sent to the acousto-optic modulator driver 420.

[0050] According to an embodiment of the present invention, through the switching characteristics of the acousto-optic modulator 410, it is possible to quickly respond to the control operation of the acousto-optic modulator driver 420 and accurately adjust the near-field saturation signal without affecting the far-field echo signal, so as to solve the problem of excessive near-field signal of the lidar, including the problem that the near-field signal cannot be used, processed and affects subsequent signals.

[0051] According to an embodiment of the present invention, the acquisition module 300 includes a reflector 310 and a telescope 320 .

[0052] The reflector 310 is used to adjust the emission direction of the parallel polarized pulse laser emitted by the polarization beam splitter prism 200 and the incident direction of the echo light signal.

[0053] The telescope 320 is used to transmit the parallel polarized pulse laser emitted by the reflector 310 to the target position and collect the echo light signal generated by scattering at the target position.

[0054] According to the embodiment of the present invention, the reflector 310 adjusts the emission direction of the parallel polarized pulse laser so that it is directed toward the target position in the atmosphere, and at the same time, enables the echo light signal in the atmosphere to return to the polarization beam splitter prism 200 .

[0055] According to an embodiment of the present invention, the telescope 320 may adopt a Cassegrain type transmitting and receiving coaxial structure, which does not require multiple transmitting and receiving adjustments, thereby achieving the emission of parallel polarized pulse lasers and the reception of echo optical signals.

[0056] According to an embodiment of the present invention, the high magnification of the telescope 320 can effectively compress the receiving field of view and improve the signal-to-noise ratio of the received echo light signal. The transmitting and receiving optical paths share the same axis, which helps to maintain the symmetry of the optical path and good optical performance.

[0057] According to an embodiment of the present invention, the above device further includes a quarter wave plate 600 disposed between the polarization beam splitter prism 200 and the acquisition module 300 for adjusting the polarization state of the parallel polarized pulse laser and the echo light signal.

[0058] According to the embodiment of the present invention, the quarter wave plate 600 is a special birefringent material that can affect the polarization state of light and is used to adjust the polarization state of parallel polarized pulse laser and echo light signal, thereby adjusting the light intensity.

[0059] According to an embodiment of the present invention, the above device further includes a narrow-band filter 700 disposed between the polarization beam splitter prism 200 and the attenuation module 400, and configured to filter the echo optical signal to obtain a filtered echo optical signal.

[0060] According to an embodiment of the present invention, the narrowband filter 700 may be a special optical element that allows light within a specific wavelength range to pass through while absorbing or reflecting light outside the wavelength range, so as to filter out optical signals of useless wavelength bands in the echo optical signal.

[0061] According to the embodiment of the present invention, by filtering the echo light signal using the narrowband filter 700, the echo light signal that can obtain accurate data can be screened out according to different application requirements.

[0062] According to an embodiment of the present invention, the above device further includes a beam expander 800 and a coupling lens 900 .

[0063] The beam expander 800 is disposed between the laser emitting module 100 and the polarization beam splitter prism 200 and is used to expand the incident pulse laser.

[0064] The coupling lens 900 is disposed between the photodetector 500 and the attenuation module 400 , and is used to couple the target echo optical signal and the far-field echo signal to the signal generator 430 .

[0065] According to an embodiment of the present invention, the beam expander 800 is used to expand the incident pulse laser and reduce the divergence angle of the incident pulse laser.

[0066] According to an embodiment of the present invention, the coupling lens 900 is used to couple the received target echo light signal and the far-field echo signal to the photodetector 500 for photoelectric conversion.

[0067] According to an embodiment of the present invention, the laser transmitting module 100 transmits an incident pulse laser, which is expanded by a beam expander 800 and then screened by a polarization beam splitter prism 200. The obtained parallel polarized pulse laser passes through a quarter wave plate 600, and the emission angle is adjusted by a reflector 310 before being emitted from a telescope 320. When the parallel polarized pulse laser contacts the target position, the echo light signal received by the telescope 320 passes through the quarter wave plate 600, the polarization beam splitter prism 200 and the narrowband filter 700, and then reaches the acousto-optic modulator 410. The acousto-optic modulator 410 attenuates the near-field saturation signal of the echo light signal to obtain a target echo light signal, and then passes through a coupling lens 900 to enable the photodetector 500 to receive the target echo light signal and the far-field echo signal and perform data processing.

[0068] Figure 3 A schematic diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to another embodiment of the present invention is shown.

[0069] According to an embodiment of the present invention, the configuration of the photoelectric detector 500 can be adjusted according to actual data processing requirements. For example, in a wind laser radar, its main optical path structure is as follows: Figure 3 shown.

[0070] The laser emission module 100 uses a 1064nm tunable seed injection laser, and the emitted laser is converted into a 354.7nm incident pulse laser after double and triple frequency conversion, and the pulse repetition frequency is 100Hz. The output 354.7nm incident pulse laser is expanded by the beam expander 800, and then screened by the first polarization beam splitter prism 210 and the first quarter wave plate 610, and finally transmitted into the atmosphere through the reflector 310 and the telescope 320 to interact with atmospheric particles.

[0071] When receiving the echo light signal, the echo light signal is first received by the telescope 320 and the reflector 310, introduced into the first quarter wave plate 610, and reflected at the first polarization beam splitter prism 210 to enter the AOM. At this time, the AOM is turned on, and the near-field saturation signal of the echo light signal is attenuated to obtain the target echo light signal. After the received target echo light signal and the far-field echo signal pass through the narrowband filter 700 and the second quarter wave plate 620, they are divided into two beams of light at the second polarization beam splitter prism 220 and enter the FP standard. After obtaining two signals of different intensities, the two coupling lenses 910 and 920 respectively couple the two signals of different intensities and enter the two photodetectors 510 and 520 for signal processing to obtain wind speed data.

[0072] Figure 4A flow chart of a near-field saturation signal attenuation method based on an acousto-optic modulator according to an embodiment of the present invention is shown.

[0073] like Figure 4 As shown, the near-field saturation signal attenuation method based on an acousto-optic modulator of this embodiment includes operations S410 to S440.

[0074] In operation S410, incident pulse laser is emitted using a laser emission module.

[0075] In operation S420, a polarization beam splitter is used to screen the incident pulse laser to obtain parallel polarized pulse laser.

[0076] In operation S430, parallel polarized pulsed laser light is emitted to a target position, and an echo light signal generated by scattering from the target position is collected.

[0077] In operation S440, when the signal generator is used to determine that the echo light signal is a near-field saturation signal, an acousto-optic modulator is used to attenuate the near-field saturation signal to obtain a target echo light signal.

[0078] According to an embodiment of the present invention, a laser transmitting module is used to transmit an incident pulse laser; a polarization beam splitter is used to screen the incident light of the incident pulse laser to obtain a parallel polarized pulse laser; the parallel polarized pulse laser is transmitted to a target position, and an echo light signal generated by scattering of the target position is collected; when a signal generator is used to determine that the echo light signal is a near-field saturation signal, an acousto-optic modulator is used to attenuate the near-field saturation signal to obtain a target echo light signal. Since a signal generator is used to determine whether the currently received echo light signal is a near-field saturation signal, the near-field saturation signal can be attenuated without affecting the far-field echo signal, thereby avoiding the problem that the signal in the vicinity is too strong, causing the detector to be saturated and the data processing system cannot extract effective information from it, so that the information obtained after processing is more accurate, which is convenient for relevant analysis and processing of the target position.

[0079] According to an embodiment of the present invention, the near-field saturation signal is determined based on the following operations: collecting a first time point of an incident pulse laser, the first time point representing the time point when the incident pulse laser completes emission; determining a second time point based on the first time point and a preset time difference, the second time point representing the time point when the near-field saturation signal collection is completed; and determining an echo light signal received earlier than the second time point as a near-field saturation signal.

[0080] Figure 5 A timing diagram of a near-field saturation signal attenuation device based on an acousto-optic modulator according to an embodiment of the present invention is shown.

[0081] According to an embodiment of the present invention, the first time point may be the time point when the incident pulse laser completes emission, and the laser emission module trigger signal and the incident pulse laser signal are sent to the signal generator in real time to provide the signal generator 430 with information that the incident pulse laser emission has been completed at the current time point.

[0082] According to an embodiment of the present invention, the preset time difference may be adjusted according to actual applications, and the preset time difference represents the time required for the near-field saturation signal of the estimated echo optical signal to return from the target position to the telescope 320 .

[0083] According to an embodiment of the present invention, the echo light signal received earlier than the second time point is determined as a near-field saturation signal; the echo light signal received later than the second time point is determined as a far-field echo signal. As shown in the figure, the echo light signal corresponding to the AOM opening period is an overly strong signal of the first returning device located nearby, that is, a near-field saturation signal.

[0084] According to an embodiment of the present invention, the timing synchronization of the AOM and other devices is ensured, so that the time period for the return of the near-field saturation signal can be determined according to the first time point information of the incident pulse laser, and the AOM is turned on only within this time period, so as to realize the attenuation of only the near-field saturation signal by the AOM.

[0085] According to an embodiment of the present invention, the incident pulse laser includes a first polarization state pulse laser and a second polarization state pulse laser; the incident pulse laser is screened by using a polarization beam splitter prism to obtain a parallel polarized pulse laser, including: using a polarization beam splitter prism to remove the second polarization state pulse laser of the incident pulse laser, and using the first polarization state pulse laser of the incident pulse laser as the parallel polarized pulse laser.

[0086] According to an embodiment of the present invention, the incident pulsed laser includes a first polarization state pulsed laser and a second polarization state pulsed laser, which are respectively a parallel polarized pulsed laser (P-polarized light, P light) and a vertical polarized pulsed laser (S-polarized light, S light), wherein the polarization beam splitter prism can transmit the P light, while the S light is basically completely reflected on the splitting plane in the middle of the polarization beam splitter prism.

[0087] According to an embodiment of the present invention, incident pulse laser is screened by using a polarization beam splitter to obtain parallel polarized pulse laser, thereby achieving precise control of the pulse laser to complete the detection of the target position.

[0088] According to an embodiment of the present invention, the echo light signal includes a first polarization state light signal and a second polarization state light signal; the method also includes: using a polarization beam splitter prism to remove the first polarization state light signal of the echo light signal, and transmitting the second polarization state light signal of the echo light signal to an acousto-optic modulator, wherein the second polarization state light signal is a vertically polarized light signal.

[0089] According to an embodiment of the present invention, the echo optical signal includes a first polarization state optical signal and a second polarization state optical signal, which are a parallel polarized light signal (P-polarized light, P light) and a vertical polarized light signal (S-polarized light, S light) respectively.

[0090] According to an embodiment of the present invention, a polarization beam splitter is used to screen the echo light signal to obtain a vertically polarized light signal, thereby enhancing the detection sensitivity and improving the data extraction efficiency to complete the detection of the target position.

[0091] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention may be combined and / or combined in various ways. All of these combinations and / or combinations fall within the scope of the present invention.

[0092] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A near-field saturation signal attenuation device based on an acousto-optic modulator, characterized in that: The device comprises: A laser emission module, used for emitting incident pulse laser; A polarization beam splitter prism, used for screening the incident pulse laser emitted by the laser emission module to obtain parallel polarized pulse laser; A collection module, used for emitting the parallel polarized pulse laser emitted by the polarization beam splitter prism to a target position, and collecting an echo light signal generated by scattering from the target position, wherein the echo light signal includes a near-field saturation signal and a far-field echo signal; an attenuation module, configured to, when determining that the echo light signal is the near-field saturation signal, attenuate the near-field saturation signal collected by the acquisition module to obtain a target echo light signal, wherein the attenuation module comprises an acousto-optic modulator, and the acousto-optic modulator is configured to attenuate the near-field saturation signal emitted by the polarization beam splitter prism to obtain the target echo light signal; The photoelectric detector is used to process the target echo light signal and the far-field echo signal emitted by the attenuation module to obtain target data for analyzing the target position.

2. The device according to claim 1, characterized in that The attenuation module also includes: an AOM driver, connected to the AOM, and used to control the start and stop of the AOM; A signal generator, one end of which is connected to the AOM driver and the other end of which is connected to the laser transmitting module, is used to generate a control instruction and send it to the AOM driver when it is determined that the echo optical signal is the near-field saturation signal.

3. The device according to claim 1, characterized in that The acquisition module comprises: A reflector, used for adjusting the emission direction of the parallel polarized pulse laser emitted by the polarization beam splitter prism and the incident direction of the echo light signal; The telescope is used to transmit the parallel polarized pulse laser emitted by the reflector to a target position and collect the echo light signal generated by scattering from the target position.

4. The device according to claim 1, characterized in that The device also includes: A quarter wave plate is arranged between the polarization beam splitter prism and the acquisition module, and is used to adjust the polarization state of the parallel polarized pulse laser and the echo light signal.

5. The device according to claim 1, characterized in that The device also includes: The narrow-band filter is arranged between the polarization beam splitter prism and the attenuation module, and is used for filtering the echo light signal to obtain a filtered echo light signal.

6. The device according to claim 2, characterized in that The device also includes: A beam expander, disposed between the laser emission module and the polarization beam splitter prism, for expanding the incident pulsed laser; A coupling lens is disposed between the photodetector and the attenuation module, and is used to couple the target echo optical signal and the far-field echo signal to the photodetector.

7. A near-field saturation signal attenuation method based on an acousto-optic modulator, characterized in that: The method comprises: Utilizing a laser transmitting module to transmit an incident pulse laser; Using a polarization beam splitter prism to screen the incident pulse laser to obtain parallel polarized pulse laser; emitting the parallel polarized pulsed laser to a target position, and collecting an echo light signal generated by scattering from the target position; When the signal generator is used to determine that the echo light signal is a near-field saturation signal, an acousto-optic modulator is used to attenuate the near-field saturation signal to obtain a target echo light signal.

8. The method according to claim 7, characterized in that The near-field saturation signal is determined based on the following operations: Collecting a first time point of the incident pulse laser, wherein the first time point represents a time point when the incident pulse laser completes emission; Determining a second time point according to the first time point and a preset time difference, wherein the second time point represents a time point when the near-field saturation signal acquisition is completed; The echo optical signal received earlier than the second time point is determined as the near-field saturation signal.

9. The method according to claim 7, characterized in that: The incident pulse laser includes a first polarization state pulse laser and a second polarization state pulse laser; The method of using a polarization beam splitter to screen the incident pulse laser to obtain parallel polarized pulse laser includes: The second polarization state pulse laser of the incident pulse laser is removed by using the polarization beam splitter prism, and the first polarization state pulse laser of the incident pulse laser is used as the parallel polarization pulse laser.

10. The method according to claim 7, characterized in that The echo optical signal includes a first polarization state optical signal and a second polarization state optical signal; The method further comprises: The first polarization state light signal of the echo light signal is removed by using the polarization beam splitter prism, and the second polarization state light signal of the echo light signal is transmitted to the acousto-optic modulator, wherein the second polarization state light signal is a vertically polarized light signal.

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