Laser three-dimensional imaging system and method based on receiving and transmitting dual-polarization modulation matching

Abstract

The invention provides a laser three-dimensional imaging system and method based on receiving and transmitting dual polarization modulation matching, and the method comprises the steps: enabling a pulse laser to transmit single-wavelength linear polarization pulse laser through a transmitting unit under the synchronous control of a transmitting unit controller, continuously rotating the laser linear polarization direction during the pulse duration, and enabling the laser linear polarization direction to be smaller than the single-wavelength linear polarization pulse laser; and finally, a laser pulse subjected to polarization modulation is emitted to a target through a laser beam expander. In the receiving unit, a telescopic optical system receives laser pulses returned from a target, the beam width is narrowed, wavelength selection is carried out through a wavelength filter, and the laser pulses pass through a polarization modulator of the receiving unit and are further decomposed to two orthogonal polarization directions through a polarization spectroscope. And the two groups of imaging objective lenses, the area array detector X and the area array detector Y are used for imaging and receiving. And finally, the digital signal processor carries out resolving processing on the digital signals obtained by the two detectors to obtain distance information of each point on the two-dimensional image plane. According to the invention, three-dimensional imaging with a longer distance, a higher resolution ratio and a higher speed is realized.

Description

Technical Field

[0001] The present invention belongs to the field of laser three-dimensional imaging, and in particular relates to a laser three-dimensional imaging system and method based on receiving and transmitting dual polarization modulation matching. Background Art

[0002] Three-dimensional imaging lidar is a new type of imaging technology, which is regarded as the next generation of technology products after passive optical imaging and active microwave imaging radar. Its technical means can fully integrate the advantages of both. Compared with passive optical imaging, because of its active illumination, it is easy to modulate the transmit and receive signals, which makes it easier to obtain target distance information and other reflection information, and realize fast three-dimensional imaging and high-precision remote sensing inversion. Compared with microwave imaging radar, it has higher angular resolution, stronger anti-interference ability, and faster imaging speed. At the same time, it has no requirements and restrictions on the relative motion between the target and the platform, and can perform high-resolution three-dimensional imaging in front of the moving platform, which microwave synthetic aperture radar (SAR) cannot do.

[0003] Three-dimensional imaging laser radar can be divided into two types according to the working mode: scanning and non-scanning. Scanning laser imaging obtains azimuth and distance information by scanning in sequence to achieve three-dimensional imaging. Non-scanning laser imaging focuses the target area on the image plane through the optical system, and then uses the array detector to receive it to directly obtain a two-dimensional image, and then obtains the distance information by demodulating and processing the signal, thereby achieving three-dimensional imaging. Non-scanning laser three-dimensional imaging has the advantages of fast imaging speed and high resolution, and can be applied to imaging of moving targets. At the same time, it also avoids the bulky scanning mechanism, and can achieve a smaller size and weight.

[0004] The array detectors used in non-scanning laser 3D imaging are divided into two categories: one is a high-speed avalanche photodiode (APD) array, and the other is a visible light and infrared array imaging detector based on CCD or CMOS architecture. The difference between the two is that the response and signal readout speed of the ADP array is very fast, reaching the order of tens of GHz, and can detect the changes in pulse waveforms modulated at high speeds in the sub-nanosecond level, so that the distance information can be directly solved using the same technical means as microwave radar. Because of the high requirements for the readout circuit, the pixel scale of the APD array is usually small at present, the achievable spatial resolution is low, and the cost is extremely high. The optical imaging array detector can reach a maximum of hundreds of Hz, and the detection result is the energy integration of the signal at least in microseconds, making it difficult to directly perceive the echo signal waveform. However, its overall process technology level is relatively mature, and the pixel scale can be very large, so that a very high spatial resolution can be achieved at a low cost.

[0005] When using an optical imaging array detector for laser three-dimensional imaging, the commonly used method is to map the return time of the echo signal to the responsiveness of the array detector pixel, and then invert the distance information from the intensity information. The ranging accuracy of this method depends on the width of the signal pulse. The narrower the pulse width, the higher the ranging accuracy. In order to ensure that the detection receives enough light energy, if the total energy of a single pulse remains unchanged, a smaller pulse width requires a higher instantaneous power within the pulse, which will greatly increase the technical requirements and cost of the laser, and bring many problems in terms of volume, heat dissipation, etc. Summary of the invention

[0006] In order to reduce the dependence on narrow pulse width and high energy of laser signals when using optical imaging array detectors for laser three-dimensional imaging, the present invention provides a laser three-dimensional imaging system and method based on receiving and transmitting dual polarization modulation matching.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching, including a transmitting unit and a receiving unit;

[0009] The transmitting unit comprises:

[0010] A pulse laser, used to generate a single-wavelength pulse laser signal in a linear polarization state;

[0011] Laser beam expander, used to adjust the laser beam width and divergence angle;

[0012] A polarization modulator of the transmitting unit, used for modulating the polarization state of the transmitted pulse laser;

[0013] A transmitter unit controller, used for synchronously controlling the pulsed laser and the polarization modulator, and continuously modulating the laser polarization state during the laser pulse duration;

[0014] The receiving unit comprises:

[0015] Telescopic optical system, used to receive the laser signal scattered by the target and shrink the input beam width;

[0016] Wavelength filter, used to filter incident light other than the laser wavelength to reduce the impact of natural light in the scene;

[0017] A receiving unit polarization modulator, used for polarization modulating the received laser signal;

[0018] Polarization beam splitter, used to split the laser signal into two orthogonal polarization directions;

[0019] An imaging objective lens, used for imaging the laser beam on a two-dimensional image plane;

[0020] Area array detector X and area array detector Y are used to convert the optical signal on the image plane into an electrical signal, and further into a digital signal;

[0021] The receiving unit controller is used to synchronously control the polarization modulator and the area array detector to ensure that the polarization modulation is synchronously matched with the imaging exposure;

[0022] A digital signal processor is used to calculate the depth information of each pixel from a two-dimensional digital image signal to obtain a three-dimensional image.

[0023] Furthermore, under the synchronous control of the transmitting unit controller, the transmitting unit emits a single-wavelength linearly polarized pulse laser from a pulse laser, passes through a linear polarizer, and then passes through a polarization modulator to continuously rotate the linear polarization direction of the laser during the pulse duration, and finally emits a polarization-modulated laser pulse to the target through a laser beam expander.

[0024] Furthermore, in the receiving unit, the laser pulses returned from the target are received by the telescopic optical system, and after the beam width is narrowed by the wavelength filter, the beam is passed through the polarization modulator of the receiving unit. The polarization modulator of the receiving unit has the same modulation rate as the polarization of the transmitting unit, but the deflection direction is opposite.

[0025] Furthermore, after the laser pulse passes through the polarization modulator of the receiving unit, the polarization state that continuously rotates during the pulse duration is transformed into a polarization state in a fixed direction, and the fixed direction maps the return time of the laser pulse, that is, the target distance.

[0026] Furthermore, the laser pulse is further decomposed into two orthogonal polarization directions by the polarization beam splitter, and is imaged and received by two groups of imaging objective lenses and the area array detector X and the area array detector Y respectively.

[0027] Furthermore, the digital signal processor performs calculation processing on the digital signals obtained by the area array detector X and the area array detector Y to obtain the distance information of each point on the two-dimensional image plane.

[0028] The present invention also provides a laser three-dimensional imaging method based on receiving and transmitting dual polarization modulation matching, comprising the following steps:

[0029] Step 1: In the transmitting unit of the laser three-dimensional imaging system based on transmitting and receiving dual polarization modulation matching, the pulsed laser generates a wavelength of , the pulse width is , the pulse energy is The linearly polarized laser pulse signal; under the synchronous control of the controller, the modulation rate of the polarization modulator is ; From the start of the laser pulse to the end of the pulse, the polarization direction of the beam rotates at a uniform speed during the duration ;

[0030] Step 2: obtaining two beams of light with orthogonal polarization directions in a receiving unit of a laser three-dimensional imaging system based on emission and reception dual polarization modulation matching, and focusing and imaging them on a planar array detector X and a planar array detector Y respectively;

[0031] Step 3: Calculate the target distance based on the pulses returned by the area array detector X and the area array detector Y.

[0032] Furthermore, the step 2 includes: receiving the laser pulses returned from the target by the telescopic optical system, narrowing the beam width and passing through the receiving unit polarization modulator, and the modulation rate is The pulses returned from different distances are modulated by the polarization modulator of the receiving unit and are in different linear polarization modulation directions. Then they are decomposed into two beams of light with orthogonal polarization directions through a polarization beam splitter and focused on the array detector X and the array detector Y respectively.

[0033] Furthermore, modulation starts from the arrival time of the return beam at the nearest gating distance.

[0034] Furthermore, the step 3 comprises:

[0035] By distance As the starting distance of gated imaging, is the speed of light; the return time of pulse A at the starting distance is ; at a distance The return time of the B pulse returned at ;

[0036] Assuming that the linear polarization direction of pulse A is in the x direction, the angle between the linear polarization direction of pulse B and the x axis is ; The energy ratio of the B pulse on a pair of pixels of the array detector X and the array detector Y is ; The digital signal processor calculates for each pixel , and then get the distance corresponding to the pixel .

[0037] Based on the above technical solution, it can be seen that the present invention has at least one of the following beneficial effects compared with the prior art:

[0038] (1) Compared with microwave imaging radar, the present invention has no restrictions on the relative motion mode of the platform and the target, and can be used for forward-looking imaging when the platform moves at high speed.

[0039] (2) Compared with APD array laser radar, the imaging reception of the present invention uses a CCD or CMOS technology-based optical array detector, which can have a higher two-dimensional resolution. Compared with scanning laser radar, it has a higher imaging frame rate and can be used for moving platforms or moving targets.

[0040] (3) Compared with laser imaging schemes that use short pulses in combination with response modulation of planar array detectors, the present invention uses a method of polarization modulation matching at both ends of the transmitter and receiver. The pulse width does not affect the distance resolution, so a long-pulse laser light source can be used. While the total pulse energy remains unchanged, the requirements for the peak power of the laser light source are reduced, the requirements for the sensitivity of the planar array detector are reduced, and the requirements for a large aperture of the receiving optical system are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of the laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching of the present invention;

[0042] Figure 2 It is a schematic diagram of the polarization state modulation method of the transmitting and receiving light beams of the present invention;

[0043] Figure 3 It is a timing diagram of transmitting and receiving signals of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. used in the present invention to indicate the orientation or position relationship is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] like Figure 1As shown, the laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching of the present invention includes a transmitting unit and a receiving unit.

[0048] Preferably, the transmitting unit comprises:

[0049] A pulse laser, used to generate a single-wavelength pulse laser signal in a linear polarization state;

[0050] Laser beam expander, used to adjust the laser beam width and divergence angle;

[0051] A polarization modulator of the transmitting unit, used for modulating the polarization state of the transmitted pulse laser;

[0052] The transmitting unit controller is used to synchronously control the pulse laser and the polarization modulator to continuously modulate the laser polarization state during the laser pulse duration.

[0053] Preferably, the receiving unit comprises:

[0054] Telescopic optical system, used to receive the laser signal scattered by the target and shrink the input beam width;

[0055] Wavelength filter, used to filter incident light other than the laser wavelength to reduce the impact of natural light in the scene;

[0056] A receiving unit polarization modulator, used for polarization modulating the received laser signal;

[0057] Polarization beam splitter, used to split the laser signal into two orthogonal polarization directions;

[0058] An imaging objective lens, used for imaging the laser beam on a two-dimensional image plane;

[0059] Area array detector X and area array detector Y are used to convert the optical signal on the image plane into an electrical signal, and further into a digital signal;

[0060] The receiving unit controller is used to synchronously control the polarization modulator and the area array detector to ensure that the polarization modulation is synchronously matched with the imaging exposure.

[0061] A digital signal processor is used to calculate the depth information of each pixel from a two-dimensional digital image signal to obtain a three-dimensional image.

[0062] The working process of a laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching of the present invention is as follows: the transmitting unit emits a single-wavelength linear polarization pulse laser by a pulse laser under the synchronous control of the transmitting unit controller, passes through a linear polarizer, and then passes through a polarization modulator, and continuously rotates the laser linear polarization direction during the pulse duration, and finally emits a polarization-modulated laser pulse to the target through a laser beam expander; in the receiving unit, the laser pulse returned from the target is received by a telescopic optical system, and after the beam width is narrowed by a wavelength filter, it passes through a receiving unit polarization modulator, and the polarization modulator of the receiving unit has the same modulation rate as the polarization of the transmitting unit, but the deflection direction is opposite. After the laser pulse passes through the receiving unit polarization modulator, it is transformed from a polarization state that continuously rotates during the pulse duration to a polarization state in a fixed direction, and the polarization direction maps the return time of the laser pulse, that is, the target distance. The laser pulse is further decomposed into two orthogonal polarization directions by a polarization beam splitter, and is imaged and received by two groups of imaging objective lenses and a planar array detector X and a planar array detector Y, respectively. Finally, under the unified coordination of the controller, the digital signal processor receives the digital signals obtained by the area array detector X and the area array detector Y, and performs calculation processing to obtain the distance information of each point on the two-dimensional image plane.

[0063] The imaging method of the present invention comprises:

[0064] The pulse laser emission wavelength is , the pulse width is , the pulse energy is Linearly polarized laser pulse signal. The pulsed laser output light pulse first passes through a linear polarizer to ensure the polarization direction is aligned, if the linear polarization direction is along the y direction. Then it passes through the polarization modulator to modulate the linear polarization direction of the pulse, such as Figure 2 Target A and target B are two targets at different distances, where target A is located at the shortest detection distance planned by the system, and its distance from the receiving unit is , c is the speed of light, T is the gating time, that is, the return time of the echo signal at target A. Target B is farther away than target A. After the same outgoing beam light pulse is reflected by both, the time difference between the echo reaching the receiving unit is , then the distance difference between target A and target B is The returned time difference is The two pulses are modulated by the polarization modulator at the receiving end to produce linearly polarized light with different polarization angles. The difference between the polarization angles is The polarization modulator can be produced by at least two methods: magneto-optical rotation effect or electro-birefringence effect in combination with a quarter wave plate.

[0065] When using the magneto-optical effect, the rotation angle It is proportional to the magnetization intensity M and the distance l, that is: .in, is the saturation magnetization, and F is the Faraday rotation coefficient. M can be controlled by the current of the electromagnetic coil, thereby Electrical modulation is achieved.

[0066] When the electro-birefringence effect is used in conjunction with a quarter wave plate, the propagation direction of the pulsed laser is along the coordinate z direction, the polarization direction is along the coordinate y direction, and the light wave electric vector E is expressed as , is the complex amplitude of the light wave, i is the imaginary unit, is the angular frequency of the light wave, For time, The direction of the fast axis f of the electro-optical birefringent crystal is 45° to the x-axis and y-axis. The phase difference introduced by the direction of the fast axis f and the direction of the slow axis s is At this time, the light emitted from the birefringent crystal is decomposed into:

[0067] The electric vector of the light wave in the direction f for:

[0068] ;

[0069] The electric vector of the light wave in the s direction for:

[0070] .

[0071] Then add a quarter wave plate, with the fast axis along the x-axis and the slow axis along the y-axis. and Decomposed into the x-axis direction and the y-axis direction respectively, they are expressed as: , , , :

[0072] ;

[0073] ;

[0074] ;

[0075] ;

[0076] The final electric vector of the light wave in the x direction is for:

[0077] ;

[0078] The electric vector of the light wave in the y direction for:

[0079] ;

[0080] right and Taking the real part we get:

[0081] ;

[0082] ;

[0083] It can be seen that the phases in the x-axis and y-axis directions are the same, and the amplitudes are and , that is, the polarization direction is deflected by an angle of 100° compared to the incident light. . It is determined by the voltage applied to the electro-optical crystal, thereby achieving electrical modulation of the deflection angle.

[0084] The polarization-modulated laser pulse is emitted toward the target area after passing through a laser beam expander.

[0085] The returned laser beam is received by the telescopic optical system. The function of the telescopic optical system is to make the light beam from a certain target point enter and exit in parallel, and the width of the beam is reduced, which is the opposite of the function of the beam expander.

[0086] The parallel light beam emitted by the telescope optical system then passes through a wavelength filter to reduce the influence of ambient light. It then enters the receiving unit polarization modulator, which starts modulating from the arrival time of the return light beam at the nearest gate distance. The pulses returned at different distances will be in different linear polarization modulation directions after being modulated by the receiving unit polarization modulator, such as Figure 2 Then, the light is decomposed into two beams with orthogonal polarization directions (x direction and y direction) through a polarization beam splitter, and then focused by an imaging objective lens to form images on the area array detector X and the area array detector Y respectively.

[0087] Preferably, the polarization modulator of the receiving unit can also adopt two modulation modes: magneto-optical rotation effect and electro-birefringence effect. Assume that the intensity of the light beam incident on the polarization modulator of the receiving unit is When the return beam from the nearest gating distance arrives, the polarization modulator of the receiving unit starts modulation.

[0088] If the electro-birefringence modulation method is used, the fast axis of the crystal is along the x-axis and the slow axis is along the y-axis. is the angle between the incident light polarization direction and the x-axis, is the angle between the polarization direction received by the array detector and the x-axis, and the light intensity incident on the modulator is , is the phase difference between the fast and slow axes of the crystal, the light intensity received by the array detector can be expressed as:

[0089] ;

[0090] If the two road array detectors are at 45° and -45° to the crystal x-axis respectively, then The laser pulse width is , the optical rotation modulation rate at the transmitting end and the crystal modulation rate at the receiving end are ,Right now , is the echo time difference of the optical pulse between target A and target B.

[0091] In order to facilitate subsequent integration, the time when each light pulse reaches the electro-optical crystal at the receiving end is taken as the zero time point, and the above formula can be written as:

[0092] ;

[0093] ;

[0094] in, and are the light intensities on the corresponding pixels of the area array detector X and area array detector Y respectively. By integrating the inner part, we can get the total light energy received by the corresponding pixels of the area array detector X and the area array detector Y during the exposure time, which are respectively expressed as and express:

[0095] ;

[0096] ;

[0097] Where C is a constant.

[0098] like , that is, the signal intensity ratio of the corresponding pixels of the array detector X and the array detector Y is m, then we can calculate :

[0099] ;

[0100] ;

[0101] If a magneto-optical crystal is used as a polarization modulator, the light intensity incident on the array detector X and the array detector Y is , for:

[0102] ;

[0103] ;

[0104] The ratio of the response values ​​of the two array detectors is:

[0105] ;

[0106] in, is the new signal strength ratio.

[0107] Thus we can get for:

[0108] ;

[0109] The target distance can be further calculated:

[0110] Calculate for each pixel , and then get the distance corresponding to the pixel Where c is the speed of light and T is the gating time, i.e. the arrival time of the target reflection echo at the predetermined minimum detection distance.

[0111] The timing of signal transmission and reception, as well as the mapping relationship between time and polarization state are as follows: Figure 3 As shown, echo A and echo B correspond to Figure 2 The echoes of target A and target B are shown in FIG. It can be seen that the distance information of the target is mapped to the ratio information of the responses of two corresponding pixels on the two detectors, thereby realizing the distance information detection of the target.

[0112] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching, characterized in that: comprising a transmitting unit and a receiving unit; The transmitting unit comprises: A pulse laser, used to generate a single-wavelength pulse laser signal in a linear polarization state; Laser beam expander, used to adjust the laser beam width and divergence angle; A polarization modulator of the transmitting unit, used for modulating the polarization state of the transmitted pulse laser; A transmitter unit controller, used for synchronously controlling the pulsed laser and the polarization modulator, and continuously modulating the laser polarization state during the laser pulse duration; The receiving unit comprises: Telescopic optical system, used to receive the laser signal scattered by the target and shrink the input beam width; Wavelength filter, used to filter incident light other than the laser wavelength to reduce the impact of natural light in the scene; A receiving unit polarization modulator, used for polarization modulating the received laser signal; Polarization beam splitter, used to split the laser signal into two orthogonal polarization directions; An imaging objective lens, used for imaging the laser beam on a two-dimensional image plane; Area array detector X and area array detector Y are used to convert the optical signal on the image plane into an electrical signal, and further into a digital signal; The receiving unit controller is used to synchronously control the polarization modulator and the area array detector to ensure that the polarization modulation is synchronously matched with the imaging exposure; A digital signal processor is used to calculate the depth information of each pixel from a two-dimensional digital image signal to obtain a three-dimensional image.

2. The laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching according to claim 1 is characterized in that: Under the synchronous control of the transmitting unit controller, the transmitting unit emits a single-wavelength linearly polarized pulse laser from a pulse laser, which passes through a linear polarizer and then a polarization modulator to continuously rotate the linear polarization direction of the laser during the pulse duration, and finally emits a polarization-modulated laser pulse to the target through a laser beam expander.

3. The laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching according to claim 1, characterized in that: In the receiving unit, the telescopic optical system receives the laser pulses returned from the target, and after the beam width is narrowed by the wavelength filter, it passes through the polarization modulator of the receiving unit. The polarization modulator of the receiving unit has the same modulation rate as the polarization of the transmitting unit, but the deflection direction is opposite.

4. The laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching according to claim 3 is characterized in that: After the laser pulse passes through the polarization modulator of the receiving unit, the polarization state that continuously rotates during the pulse duration is transformed into a polarization state in a fixed direction. This fixed direction maps the return time of the laser pulse, that is, the target distance.

5. The laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching according to claim 4, characterized in that: The laser pulse is further decomposed into two orthogonal polarization directions by a polarization beam splitter and received by two sets of imaging objectives and array detectors X and Y, respectively.

6. The laser three-dimensional imaging system based on receiving and transmitting dual polarization modulation matching according to claim 5, characterized in that: The digital signal processor processes the digital signals obtained by the array detector X and the array detector Y to obtain the distance information of each point on the two-dimensional image plane.

7. A laser three-dimensional imaging method based on receiving and transmitting dual polarization modulation matching, characterized in that: The steps include: Step 1: In the transmitting unit of the laser three-dimensional imaging system based on transmitting and receiving dual polarization modulation matching, the pulsed laser generates a wavelength of , the pulse width is , the pulse energy is The linearly polarized laser pulse signal; under the synchronous control of the controller, the modulation rate of the polarization modulator is ; From the start of the laser pulse to the end of the pulse, the polarization direction of the beam rotates at a uniform speed during the duration ; Step 2: obtaining two beams of light with orthogonal polarization directions in a receiving unit of a laser three-dimensional imaging system based on emission and reception dual polarization modulation matching, and focusing and imaging them on a planar array detector X and a planar array detector Y respectively; Step 3: Calculate the target distance based on the pulses returned by the area array detector X and the area array detector Y.

8. The laser three-dimensional imaging method based on receiving and transmitting dual polarization modulation matching according to claim 7, characterized in that: The step 2 includes: receiving the laser pulses returned from the target by the telescopic optical system, narrowing the beam width and passing through the receiving unit polarization modulator, and the modulation rate is The pulses returned from different distances are modulated by the polarization modulator of the receiving unit and are in different linear polarization modulation directions. Then they are decomposed into two beams of light with orthogonal polarization directions through a polarization beam splitter and focused on the array detector X and the array detector Y respectively.

9. The laser three-dimensional imaging method based on receiving and transmitting dual polarization modulation matching according to claim 8, characterized in that: Modulation starts from the arrival time of the return beam at the nearest gating distance.

10. The laser three-dimensional imaging method based on receiving and transmitting dual polarization modulation matching according to claim 7, characterized in that: The step 3 comprises: By distance As the starting distance of gated imaging, is the speed of light; the return time of pulse A at the starting distance is ; at a distance The return time of the B pulse returned at ; Assuming that the linear polarization direction of pulse A is in the x direction, the angle between the linear polarization direction of pulse B and the x axis is ; The energy ratio of the B pulse on a pair of pixels of the array detector X and the array detector Y is ; The digital signal processor calculates for each pixel , and then get the distance corresponding to the pixel .

Images