A coherent light laser radar system using focal plane imaging

Abstract

The present invention discloses a coherent light laser radar system using focal plane imaging, wherein the light emitted by the light source enters the first lens group, the signal light thereof is emitted to the target through the second lens group, the signal light reflected by the target is received by the fourth lens group, and a real image is formed on the second image plane, the real image is expanded by a fifth lens group, and then enters the first beam combiner; the local oscillator light thereof generates a laser beam waist at the first image plane through the third lens group, and after being expanded by another fifth lens group, enters the beam combiner, and then converges by the sixth lens group, a sensor array is placed on the third image plane, the sensor array is connected to a signal processing module, and the electrical signal is calculated and processed and then output. By making the propagation directions of the signal light and the local oscillator light nearly parallel, the beam combiner focuses them on the image plane, and the sensor array on the image plane is used to realize the coherent speed measurement and distance measurement of the focal plane array, effectively avoiding the phase misalignment of the AC component, and improving the signal-to-noise ratio.

Description

Technical Field

[0001] The invention belongs to the field of electronic information technology and relates to a coherent light laser radar system using focal plane imaging. Background Art

[0002] Coherent optical ranging is an optical ranging method that uses the coherence of light to measure distance. Its principle is to use the coherence of light to obtain the optical beat frequency signal after interference, and the distance information is obtained from the frequency change loaded on the optical signal.

[0003] Assume that the angular frequencies of the local oscillator light and the signal light are ω L and ω s , the corresponding phase φ L and φ S , the corresponding electric field amplitudes are:

[0004]

[0005] When the local oscillator light and the signal light interfere with each other on the photosensitive surface of the detector, the photocurrent is:

[0006]

[0007] In the formula, α is the photoelectric response rate of the photodetector. It can be obtained that the photocurrent has an AC term with a frequency of ω = ω L -ω S , its phase is φ=φ L -φ s By detecting the frequency of the photocurrent, the distance to the target can be obtained.

[0008] In addition, due to the Doppler effect, the echo generated by irradiating a target with a relative velocity will produce a Doppler frequency shift, the size of which can be calculated by the following formula:

[0009]

[0010] In the above formula, v is the radial velocity of the target and the detection source, and λ is the wavelength of the detection light. When the target is close to the detection source, f d >0, when the target principle detects the source, f d <0.

[0011] At present, the mainstream detection scheme is still based on single-point detection or its variants. Single-point means that there is a set of transmitter and receiver in a transceiver unit, and only one distance measurement / speed measurement result is output in the end. Through multiple sets of detector arrays, large-angle coverage is achieved. Specific implementation forms include:

[0012] (1) Mechanical scanning: Multiple single-point transceiver modules are combined into a linear array, and then scanned by a rotating scanning mechanism, so as to achieve wide angle coverage. This mechanical rotation method is the most traditional scanning mode.

[0013] (2) MEMS scanning: The single-channel module for transmission and reception is fixed, and one or more MEMS micro-vibration mirrors are used to deflect and scan the transmission and reception lasers. Because the main components of this scanning method do not need to move, this method is called "semi-solid-state".

[0014] (3) Use scanning devices such as optical phased array (OPA). This is a fully solid-state scanning mode with no moving parts. OPA can control the phase of the light field, thereby changing the angle of transmission and reception.

[0015] Among the above three solutions, (1) and (2) still have movable or rotating parts, which greatly reduces their reliability, and the OPA used in (3) is still not very mature. Therefore, it is very necessary to design a completely solid-state lidar solution without movable parts. Summary of the invention

[0016] The purpose of the present invention is to solve the problem in the prior art that when focal plane array imaging is performed, due to the different phases of multiple points within a pixel, the AC component of the photocurrent is misaligned in phase, and after the photocurrents in different areas are added, the AC components cancel each other out, resulting in a decrease in the signal-to-noise ratio. A coherent light laser radar system using focal plane imaging is provided.

[0017] In order to achieve the above object, the present invention adopts the following technical solutions:

[0018] A coherent light laser radar system using focal plane imaging, comprising a light source, a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a first beam combiner and a sixth lens group;

[0019] The light emitted from the light source enters the first lens group, which is collimated, shaped and split by the first lens group to divide the light into signal light and local oscillator light. The signal light is emitted to the target through the second lens group. The fourth lens group receives the signal light reflected from the target and forms a real image on the second image plane. The real image is expanded by one of the fifth lens groups and then enters the first beam combiner. The local oscillator light is shaped and focused by the third lens group to generate a laser beam waist at the first image plane. The laser beam waist is expanded by another fifth lens group and then enters the first beam combiner. After both the signal light and the local oscillator light pass through the first beam combiner, they are converged by the sixth lens group to achieve coherence of the signal light and the local oscillator light on the third image plane. A first sensor array is placed on the third image plane. After the first sensor array completes the photoelectric conversion, the electrical signal is input into the signal processing module. The signal processing module performs calculation processing on the electrical signal and then outputs it.

[0020] A further improvement of the present invention is:

[0021] After the signal light and the local oscillator light pass through the first beam combiner, they enter the first beam splitter to split the light into two paths. The first path of light forms a first real image on the third image plane after passing through the sixth lens group, and the second path of light forms a second real image on the fourth image plane after passing through the seventh lens group. The first sensor array and the second sensor array are respectively placed at the third image plane and the fourth image plane. After the first sensor array and the second sensor array complete the photoelectric conversion, the electrical signals are input into the signal processing module.

[0022] The first real image and the second real image are identical or mirror images of each other.

[0023] The sixth lens group and the seventh lens group have the same structure or the same optical function.

[0024] The laser beam waist is generated at the first image plane, and 1 / e of the laser beam waist 2 The radius is r 1 The fourth lens group receives the signal light reflected from the target and forms a real image on the second image plane. The radius of the real image is r 2 .

[0025] 1 / e of the laser beam waist 2 Radius r 1 Greater than the real image radius r on the second image plane 2 .

[0026] The real image on the second image plane is expanded by one of the fifth lens groups to become a 4 , the divergence angle is θ 4 The laser beam waist is expanded by another fifth lens group and collimated to 1 / e of the divergence angle. 2 The radius is r 3 , the divergence angle is θ3 Approximately parallel light.

[0027] The radius r of the approximately parallel light formed by the expansion of the real image on the second image plane 4 The radius r of the approximately parallel light formed after beam expansion is smaller than the laser beam waist 3 ; The divergence angle θ of the approximately parallel light formed after the real image on the second image plane is expanded 4 The divergence angle θ of the nearly parallel light formed after beam expansion is greater than the laser beam waist 3 .

[0028] The light source is an external cavity narrow line width laser, a distributed Bragg grating laser or an acousto-optic modulator.

[0029] The electrical signal is an analog current signal, an analog voltage signal or a digital signal, and the data output by the signal processing module is the speed, distance, three-dimensional coordinate information or point cloud information of the measured target.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention proposes a coherent light laser radar system using focal plane imaging, which divides the light emitted by a light source into signal light and local oscillator light, expands, collimates and shapes the light through a lens group respectively, so that the propagation directions of the two are nearly parallel, and then focuses the local oscillator light and the signal light through a beam combiner, focuses them on an image plane, performs photoelectric signal conversion through a sensor array on the image plane, and calculates and processes the electrical signal in a signal processing module to obtain the speed and distance information of the target, thereby realizing the coherent speed and distance measurement of the focal plane array, effectively avoiding the phase misalignment of the AC component, and improving the signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic diagram showing the optical path structure of a laser radar system when the light source is a fiber laser;

[0034] Figure 2 A schematic diagram showing the optical path structure of a laser radar system when the light source is a spatial light laser;

[0035] Figure 3 Schematic diagram of the optical path structure of the laser radar system when performing array balanced detection.

[0036] Among them: 1-light source, 2-first lens group, 3-second lens group, 4-third lens group, 5-first image plane, 6-fifth lens group, 7-fourth lens group, 8-second image plane, 9-fifth lens group, 10-first beam combiner, 11-sixth lens group, 12-third image plane, 13-first beam splitter, 14-seventh lens group, 15-fourth image plane, 16-first sensor array, 17-second sensor array, 18-signal processing module. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply 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 a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0041] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0044] The present invention proposes a coherent light laser radar system using focal plane imaging, comprising a light source 1, a first lens group 2, a second lens group 3, a third lens group 4, a fourth lens group 7, a fifth lens group 6, 9, a first beam combiner 10 and a sixth lens group 11; the light emitted from the light source 1 enters the first lens group 2, is collimated, shaped and split by the first lens group 2, and is divided into signal light and local oscillation light, the signal light is emitted to the target through the second lens group 3, the fourth lens group 7 receives the signal light reflected from the target, and forms a real image on the second image plane, and the real image is imaged by one of the fifth lens groups After beam expansion, it enters the first beam combiner 10; after the local oscillation light is shaped and focused by the third lens group 4, a laser beam waist is generated at the first image plane 5. After the laser beam waist is expanded by one of the fifth lens groups, it enters the first beam combiner 10. After both the signal light and the local oscillation light pass through the first beam combiner 10, they are converged by the sixth lens group 11 to achieve coherence of the signal light and the local oscillation light on the third image plane 12. A first sensor array 16 is placed on the third image plane 12. After the first sensor array 16 performs photoelectric signal conversion, the electrical signal is input into the signal processing module 18.

[0045] The present invention adopts six lens groups with different functions, each of which is composed of one or more optical lenses, which together form a complete set of optical equipment to complete the designed function.

[0046] The function of the first lens group is to collimate and shape the laser, which can be applied to spatial light lasers and fiber lasers. Its functions include laser collimation, shaping, and beam splitting. The beam splitting function is to divide the light emitted by the laser into two paths: signal light and local oscillator light. The signal light is emitted through the second lens group, and the local oscillator light is transmitted to the first beam combiner through the third lens group to complete the beam combination of the local oscillator light and the signal light reflected from the target.

[0047] The function of the second lens group is to collimate and shape the emitted signal light, adjust it to the required field of view (FOV) / divergence angle, and project the signal light onto the target to be measured.

[0048] The function of the third lens group is to shape the laser beam obtained by beam splitting, focus the laser beam input by optical fiber or spatial light, and generate a beam with a radius of r at the first image plane. 1 The laser beam waist.

[0049] The function of the fourth lens group is to receive the signal light reflected from the target and form a real image on the second image plane. The image radius of this lens is r 2 , r 2 and r 1 There is no fixed relationship between them. However, in actual use, it is recommended to 2 <r 1 .

[0050] The function of the fifth lens group is as follows: The fifth lens group is divided into two parts, one of which is used to expand the laser beam waist of the first image plane to a radius of r 3 , the divergence angle is θ 3 Another fifth lens group is used to expand the laser beam waist of the second image plane to a radius of r. 4 , the divergence angle is θ 4 The purpose of this design is to make the propagation directions of the signal light and the local oscillator light nearly parallel after expansion, collimation and shaping, and then the local oscillator light and the signal light can be better converged on the third image plane at the same time through the sixth lens group.

[0051] The function of the sixth lens group is to focus the local oscillator light and the signal light combined by the first beam combiner onto the third image plane. Finally, a sensor array or a detector array is placed on the third image plane, and each pixel performs the functions of distance measurement and speed measurement.

[0052] The function of the sensor array is to convert optical signals into electrical signals. The available devices are photodiodes or photodiode arrays. The forms of electrical signals include but are not limited to analog current signals, analog voltage signals, and digital signals.

[0053] Signal processing module: converts the electrical signal obtained from the sensor array into the required information, including but not limited to: the distance of the target, the speed of the target, the beat frequency information obtained by the coherence of the local oscillator light and the signal light, three-dimensional coordinate information and point cloud information. The embodiment of the signal processing module includes but is not limited to: a processing circuit made on the same chip as the sensor or sensor array, a discrete processing circuit that is not on the same chip as the sensor or sensor array, and any electronic device with computing capabilities such as a computer, a single-chip microcomputer, a mobile phone terminal or a CPU.

[0054] Example 1

[0055] Figure 1 The schematic diagram of the optical path structure of the lidar system when the light source is a fiber laser, which can realize coherent ranging using a focal plane array. The solid arrow in the figure represents the local oscillator light, and the dotted arrow represents the signal light.

[0056] The laser emitted by the light source 1 is collimated and shaped by the first lens group 2. The first lens group 2 is a fiber optic beam splitter. The splitting ratio of the fiber optic beam splitter can be adjusted accordingly according to the actual system design. The laser is split into two beams by the fiber optic beam splitter, which serve as the local oscillator light and the signal light respectively.

[0057] After the light passes through the first lens group 2, it is divided into two paths, one is the signal light, which enters the second lens group 3, and the other is the local oscillation light, which enters the third lens group 4.

[0058] The signal light emitted outward passes through the second lens group 3 and is projected toward the target. The divergence angle of the projected light is adjusted according to the system design, and the divergence angle is 1 / e 2 The radius is larger than the receiving field of view.

[0059] When the light source 1 is a fiber laser, the third lens group 4 includes a fiber collimator. The light passes through the fiber collimator and becomes convergent light, and forms a laser beam waist on the first image plane 5. The 1 / e 2 The radius is r 1 After that, it is collimated by the fifth lens group 6 to 1 / e of the divergence angle. 2 The radius is r 3 , the divergence angle is θ 3 The divergence angle of the nearly parallel light is required to be |θ 3 |≈0. Then, it passes through the first beam combiner 10 and enters the sixth lens group 11.

[0060] The signal light reflected from the target is converged on the second image plane 8 through the fourth lens group 7 to form a radius r 2 The real image of 2 <r 1 .

[0061] The real image on the second image plane 8 is expanded by the fifth lens group 9 to become a beam with a radius of r 4 , the divergence angle is θ 4 The approximate parallel light is preferably r 4 <r 3 ,θ 3 <θ 4 After that, it enters the first beam combiner 10 .

[0062] After the local oscillator light and the signal light pass through the first beam combiner 10, they are converged by the sixth lens group 11 and converged into a real image on the third image plane 12, thereby achieving coherence of the two light beams.

[0063] A first sensor array 16 for detection is placed on the third image plane 12. The first sensor array 16 converts the optical signal into an electrical signal, and then inputs the electrical signal into a signal processing module 18. In the signal processing module 18, the conversion between the time domain and the frequency domain is completed, and the beat frequency signal generated by the corresponding target is calculated. Then, the speed and distance information of the corresponding target are calculated based on the beat frequency signal.

[0064] Example 2

[0065] See also Figure 2 , which shows the schematic diagram of the optical path structure of the laser radar system when the light source is a spatial light laser, and realizes the implementation method of coherent ranging using a focal plane array. The arrow in the figure represents the local oscillator light, and the dotted arrow represents the signal light.

[0066] The laser emitted by the light source 1 is collimated and shaped by the first lens group 2 and is divided into two beams, which are used as the local oscillator light and the signal light respectively. The structure of the first lens group 2 is matched. When the light source 1 emits spatial light, the first lens group 2 is a beam expander or a spatial light beam splitter; when the light source 1 emits optical fiber output, the first lens group 2 is an optical fiber coupler, an optical fiber beam splitter or a spatial light beam splitter.

[0067] After the light passes through the first lens group 2, it is divided into two paths, one is the signal light, which enters the second lens group 3, and the other is the local oscillation light, which enters the third lens group 4.

[0068] The signal light emitted outward passes through the second lens group 3 and is projected toward the target. The divergence angle of the projected light is adjusted according to the system design, and the preferred divergence angle is 1 / e 2 The radius should be larger than the receiving field of view.

[0069] When the light source 1 is a fiber laser, the third lens group 4 includes a fiber collimator. The light passes through the fiber collimator and becomes convergent light, and forms a laser beam waist on the first image plane 5. The 1 / e 2 The radius is r 1 After that, it is collimated by the fifth lens group 6 to 1 / e of the divergence angle. 2 The radius is r 3 , the divergence angle is θ 3 The divergence angle of the nearly parallel light is required to be |θ 3 |≈0. Then it passes through the first beam combiner 10 and enters the sixth lens group 11.

[0070] The signal light reflected from the target is converged on the second image plane 8 through the fourth lens group 7 to form a radius r 2 The real image, preferably r 2 <r 1 .

[0071] The real image on the second image plane 8 is expanded by the fifth lens group 9 to become a beam with a radius of r 4 , the divergence angle is θ 4 The approximate parallel light is preferably r 4 <r 3 ,θ 3 <θ 4 After that, it enters the first beam combiner 10 .

[0072] After the local oscillator light and the signal light pass through the first beam combiner 10, they are converged by the sixth lens group 11 and converged into a real image on the third image plane 12, thereby achieving coherence of the two light beams.

[0073] A first sensor array 16 for detection is placed on the third image plane 12. The first sensor array 16 converts the optical signal into an electrical signal, and then inputs the electrical signal into a signal processing module 18. In the signal processing module 18, the conversion between the time domain and the frequency domain is completed, and the beat frequency signal generated by the corresponding target is calculated. Then, the speed and distance information of the corresponding target are calculated based on the beat frequency signal.

[0074] Example 3

[0075] See also Figure 3 , which represents the schematic diagram of the optical path structure of the laser radar system when performing area array balanced detection. If it is necessary to perform area array balanced detection, that is, to use two identical sensor arrays to obtain the same current signal, and finally to achieve the effect of pixel-by-pixel balanced detection, then a set of mirrored optical paths can be used after the receiving end to obtain two image planes, and a sensor is placed on each of the two image planes to achieve the effect of balanced detection. The specific implementation steps are as follows:

[0076] The normal optical path is the same as the above, except that a first beam splitter 13, a seventh lens group 14 and a fourth image plane 15 are added. The seventh lens group 14 and the sixth lens group 11 should have the same structure in principle, and the images received by the fourth image plane 15 and the third image plane 12 should be the same or mirror images.

[0077] The light passing through the first beam combiner 10 enters the first beam splitter 13 and is divided into two paths, entering the sixth lens group 11 and the seventh lens group 14 respectively.

[0078] The light is converged on the third image plane 12 through the sixth lens group 11 to form a first real image. At the same time, the light is converged on the fourth image plane 15 through the seventh lens group 14 to form a second real image. The first real image and the second real image are the same or mirror images of each other.

[0079] A first sensor array 16 and a second sensor array 17 are respectively placed at the third image plane 12 and the fourth image plane 15 . The first sensor array 16 and the second sensor array 17 are used to receive the beat frequency signal.

[0080] The currents output by the pixels of the first sensor array 16 and the second sensor array 17 corresponding to the same target are differentially output, and the time domain and frequency domain are converted in the signal processing module 18 to obtain the distance measurement and speed measurement results.

[0081] The coherent light laser radar system using focal plane imaging in the present invention divides the light emitted by the light source into signal light and local oscillator light, expands, collimates and shapes the light through a lens group respectively, so that the propagation directions of the two are nearly parallel, and then the local oscillator light and the signal light are focused by a beam combiner onto an image plane, photoelectric signal conversion is performed through a sensor array on the image plane, and the electrical signal is calculated and processed in a signal processing module to obtain the speed and distance information of the target, thereby realizing the coherent speed and distance measurement of the focal plane array, effectively avoiding the phase misalignment of the AC component, and improving the signal-to-noise ratio.

[0082] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A coherent light lidar system using focal plane imaging, characterized in that, it includes a light source (1), a first lens group (2), a second lens group (3), a third lens group (4), a fourth lens group (7), a fifth lens group (6, 9), a first beam combiner (10) and a sixth lens group (11); The light emitted from the light source (1) enters the first lens group (2), and is collimated, shaped and split by the first lens group (2) to divide the light into signal light and local oscillator light. The signal light is emitted to the target through the second lens group (3), and the fourth lens group (7) receives the signal light reflected from the target and forms a real image on the second image plane (8). After the real image is expanded by one of the fifth lens groups, it enters the first beam combiner (10); the local oscillator light is shaped and focused by the third lens group (4), and a laser beam waist is generated at the first image plane (5). After the laser beam waist is expanded by the other fifth lens group, it enters the first beam combiner (10). After both the signal light and the local oscillator light pass through the first beam combiner (10), they are converged by the sixth lens group (11) to achieve the coherence of the signal light and the local oscillator light on the third image plane (12). A first sensor array (16) is placed on the third image plane (12). After the first sensor array (16) completes the photoelectric conversion, it inputs the electrical signal to the signal processing module (18), and the signal processing module (18) performs calculation and processing on the electrical signal and then outputs it.

2. A coherent light lidar system using focal plane imaging as described in claim 1, characterized in that, after both the signal light and the local oscillator light pass through the first beam combiner (10), they enter the first beam splitter (13) to divide the light into two paths. The first path of light forms a first real image on the third image plane (12) after passing through the sixth lens group (11), and at the same time, the second path of light forms a second real image on the fourth image plane (15) after passing through the seventh lens group (14); a first sensor array (16) and a second sensor array (17) are respectively placed at the third image plane (12) and the fourth image plane (15). After the first sensor array (16) and the second sensor array (17) respectively complete the photoelectric conversion, they input the electrical signals to the signal processing module (18).

3. A coherent light lidar system using focal plane imaging as described in claim 2, characterized in that, the first real image and the second real image are the same or mirror images of each other.

4. A coherent light lidar system using focal plane imaging as described in claim 2, characterized in that, the sixth lens group (11) and the seventh lens group (14) have the same structure or the same optical function.

5. A coherent light lidar system using focal plane imaging as described in claim 1, characterized in that, The laser beam waist is generated at the first image plane (5), and 1 / e of the laser beam waist 2 The radius is r 1 The fourth lens group (7) receives the signal light reflected from the target and forms a real image on the second image plane. The radius of the real image is r 2 .

6. A coherent light lidar system using focal plane imaging as described in claim 5, characterized in that, 1 / e of the laser beam waist 2 Radius r 1 Greater than the real image radius r on the second image plane 2 .

7. A coherent light lidar system using focal plane imaging as described in claim 1, characterized in that, The real image on the second image plane (8) is expanded by one of the fifth lens groups to have a radius of r. 4 , the divergence angle is θ 4 The laser beam waist is expanded by another fifth lens group and collimated to 1 / e of the divergence angle. 2 The radius is r 3 , the divergence angle is θ 3 Approximately parallel light.

8. A coherent light lidar system using focal plane imaging as described in claim 7, characterized in that, The radius r of the approximately parallel light formed after the real image on the second image plane (8) is expanded is 4 The radius r of the approximately parallel light formed after beam expansion is smaller than the laser beam waist 3 ; The divergence angle θ of the approximately parallel light formed after the real image on the second image plane (8) is expanded 4 The divergence angle θ of the nearly parallel light formed after beam expansion is greater than the laser beam waist 3 .

9. A coherent light laser radar system using focal plane imaging as claimed in claim 1, It is characterized in that The light source (1) is an external cavity narrow linewidth laser, a distributed Bragg grating laser or an acousto-optic modulator.

10. The coherent light laser radar system using focal plane imaging as claimed in claim 1, It is characterized in that The electrical signal is an analog current signal, an analog voltage signal or a digital signal, and the data output by the signal processing module (18) is the speed, distance, three-dimensional coordinate information or point cloud information of the measured target.

Images