A sensor array test platform using coherent probing

Abstract

The application discloses a kind of sensor array test platform using coherent detection, optical lens group is divided into signal light and local light in the laser emitted in light source, signal light is projected to target, after reflection, beam expanding is formed approximately parallel light, local light is formed approximately parallel light after convergence, collimation;After both are combined, respectively in two image planes, convergence, realize the coherence of signal light and local light, sensor array is connected after motion control module, respectively placed in the position of two image planes, sensor array converts optical signal into electrical signal, host computer converts electrical signal into measurement information.By using motion control module to move the sensor array to be measured, the optical path is more stable, the target speed and distance information are obtained by calculating in the host computer, the coherent velocity measurement and ranging of focal plane array are realized, which is closer to the actual test environment, effectively tests the area covered by a larger area, and completes the test of the whole array at the same time, saving test time.

Description

Technical Field

[0001] This invention belongs to the field of electronic information technology and relates to a sensor array test platform using coherent detection. Background Technology

[0002] Coherent detection lidar is a type of lidar that utilizes the coherence of light. Compared with traditional lidar, it has three advantages: (1) it can simultaneously perform ranging and velocity measurement, (2) it has local oscillator gain, which can improve the ranging range, and (3) it has strong anti-interference capabilities. Therefore, it is unanimously regarded by the industry as the ultimate form of lidar in the future.

[0003] Current coherent lidar primarily relies on single-point detection. "Single-point detection" refers to a single transceiver unit with a set of transmitters and receivers, ultimately outputting only a single ranging / velocity measurement result. In other words, the detector within a single lens group is considered a point that cannot be further subdivided. To achieve wider detection coverage, a scanning mechanism and multiple sets of single-point detection transceiver structures are required to realize large-angle coverage.

[0004] Currently, some researchers have proposed coherent lidar architectures using focal plane arrays as receiver detectors. This architecture, employing a single transceiver lens group, can achieve a result output greater than 1, realizing a large detection field of view (FOV). Therefore, for coherent lidar, testing the detector array is an important component under test. Unlike traditional ITOF sensors that acquire signals through integration and DTOF sensors that use pulse triggering, coherent detection sensors output a continuous current signal. After acquiring the current signal, it is converted into a frequency domain signal. Summary of the Invention

[0005] The purpose of this invention is to solve the problem in the prior art that large-array sensors require scanning mechanisms to achieve wide-angle coverage, making it impossible to complete the test in one go and resulting in low testing efficiency. The invention provides a sensor array testing platform using coherent detection.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A sensor array test platform using coherent detection includes a light source, an optical lens group, a sensor array, a motion control module, and a host computer;

[0008] The optical lens assembly splits the laser emitted from the light source into signal light and local oscillator light. The signal light is projected toward the target and expanded after reflection to form approximately parallel light. The local oscillator light is converged and collimated to form approximately parallel light. The approximately parallel light formed by the signal light and the approximately parallel light formed by the local oscillator light are combined and split, and then converge on two image planes respectively, achieving coherence between the signal light and the local oscillator light on the image planes. After the sensor array is connected to the motion control module, it is placed at the positions of the two image planes. The sensor array converts the optical signal into an electrical signal and transmits it to the host computer. The host computer converts the electrical signal into measurement information and changes the position of the sensor array by controlling the movement of the motion control module.

[0009] A further improvement of the present invention is that:

[0010] The optical lens group includes 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;

[0011] Light emitted from the light source enters the first lens group, where it is collimated, shaped, and split into signal light and local oscillator light. The signal light is emitted to the target through the second lens group, and the fourth lens group receives the signal light reflected from the target, forming 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, generating 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, achieving coherence between the signal light and the local oscillator light on the third image plane.

[0012] Both the signal light and the local oscillator light pass through the first beam combiner and then enter the first beam splitter to split the light into two paths. The first path of light passes through the sixth lens group and forms a first real image on the third image plane. At the same time, the second path of light passes through the seventh lens group and forms a second real image on the fourth image plane. The sensor array under test and the reference sensor array are placed at the third and fourth image planes, respectively. After the sensor array under test and the reference sensor array complete photoelectric conversion, they input the electrical signal to the host computer.

[0013] The motion control module includes a first displacement stage and a second displacement stage. The array of sensors to be tested is mounted on the first displacement stage, and the array of reference sensors is mounted on the second displacement stage. Both the first displacement stage and the second displacement stage are connected to a host computer.

[0014] The host computer is a computer, a microcontroller, or a PLC controller.

[0015] The electrical signal can be an analog current signal, an analog voltage signal, or a digital signal.

[0016] The measurement information includes the target's distance, target speed, and beat frequency.

[0017] The sensor array is a photodiode array.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention proposes a sensor array testing platform using coherent detection. The light emitted from the light source is divided into signal light and local oscillator light, which are then expanded, collimated, and shaped to make their propagation directions nearly parallel. These are then converged onto the image plane. The sensor array converts the optical signal into an electrical signal, and a motion control module moves the sensor array under test, making the optical path more stable. Finally, the electrical signal is processed in the host computer to obtain the target's velocity and distance information. This achieves coherent velocimetry and ranging of the focal plane array, effectively avoiding phase misalignment caused by AC components, improving the signal-to-noise ratio, generating a test environment closer to real-world usage conditions, and effectively covering a large area. Simultaneous testing of the entire array is possible, saving testing time and reducing inconsistencies in the test environment when switching between different test pixels or test areas, thus improving testing efficiency. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the sensor array test platform architecture of the present invention.

[0022] Wherein: 1-light source, 2-first lens group, 3-second lens group, 4-third lens group, 5-first image plane, 6, 9-fifth lens group, 7-fourth lens group, 8-second image plane, 10-first beam combiner, 11-sixth lens group, 12-third image plane, 14-seventh lens group, 15-fourth image plane, 16-detector array, 17-reference sensor array, 18-host computer, 19-first displacement stage, 20-second displacement stage. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0029] The present invention will now be described in further detail with reference to the accompanying drawings:

[0030] See Figure 1 This invention provides a sensor array testing platform using coherent detection, 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, a sixth lens group 11, a third image plane 12, a seventh lens group 14, a fourth image plane 15, a sensor array under test 16, a reference sensor array 17, a host computer 18, a first displacement stage 19, and a second displacement stage 20. Light emitted from the light source 1 enters the first lens group 2, where it is collimated, shaped, and split 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, forming a real image on the second image plane 8. This real image is then expanded by one of the fifth lens groups before entering the first beam combiner 10. The local oscillator light is shaped and focused by the third lens group 4, generating a laser beam waist at the first image plane 5. The laser beam waist is then focused by another fifth lens group. After beam expansion, the light enters the first beam combiner 10. 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 split the light into two paths. The first path of light passes through the sixth lens group 11 and forms a first real image on the third image plane 12. At the same time, the second path of light passes through the seventh lens group 14 and forms a second real image on the fourth image plane 15. The sensor array under test 16 and the reference sensor array 17 are respectively placed at the third image plane 12 and the fourth image plane 15. After photoelectric conversion, the sensor array under test 16 and the reference sensor array 17 respectively input electrical signals to the host computer 18. The host computer 18 is also connected to a motion control module, which includes a first displacement stage 19 and a second displacement stage 20. The sensor array under test 16 is mounted on the first displacement stage 19, and the reference sensor array 17 is mounted on the second displacement stage 20. Both the first displacement stage 19 and the second displacement stage 20 are connected to the host computer 18.

[0031] The specific working process of this invention is as follows:

[0032] If area array balanced detection is required, i.e., using two identical sensor arrays to acquire the same current signal and ultimately achieving pixel-by-pixel balanced detection, a mirrored optical path can be used after the receiver to obtain two image planes. A sensor can then be placed on each of these two image planes to achieve the balanced detection effect. The steps are as follows:

[0033] The laser emitted by the light source 1 is collimated and shaped by the first lens group 2 and divided into two beams, which serve as the local oscillator light and the signal light respectively. Among them, the design of the first lens group 2 needs to match the form of the light source. If the light source emits spatial light, it is expanded or collimated, including an expander, or a collimation radius, or a spatial light splitter. If the light source is fiber-optic output, the first lens group includes a fiber-optic coupler, a fiber-optic splitter, or a spatial light splitter.

[0034] After the light passes through the first lens group 2, it is divided into two paths. One path is the signal light, which enters the second lens group 3, and the other path is the local oscillator light, which enters the third lens group 4.

[0035] The signal light emitted outward passes through the second lens group 3 and projects towards the target. The divergence angle of the projected light is determined according to the system design. Preferably, the 1 / e 2 radius should be greater than the receiving field angle.

[0036] When the light source 1 uses a fiber laser, the third lens group 4 includes a fiber collimator. The light passes through the fiber-optic coupler, becomes convergent light, and forms a spot waist on the first image plane 5. The 1 / e 2 radius is r1. Then, it is collimated by the fifth lens group 6 to become an approximately parallel light with a divergence angle of 1 / e 2 radius of r3 and a divergence angle of θ3. The divergence angle requirement is |θ3|≈0. Then it enters the first beam combiner 10 and then enters the sixth lens group 11.

[0037] The signal light reflected from the target is converged by the fourth lens group 7 on the second image plane 8 to form a real image with a radius of r2. In principle, it is recommended that r2 < r1.

[0038] The real image on the second image plane 8 is expanded by the fifth lens group 9 to become an approximately parallel light with a radius of r4 and a divergence angle of θ4. To ensure better imaging quality, it is recommended that r4 < r3 and θ3 < θ4. Then, it enters the first beam combiner 10.

[0039] After both the local oscillator light and the signal light pass through the first beam combiner 10, they are first split by the first beam splitter 13. The transmitted light is converged by the sixth lens group 11 and converges into a real image on the third image plane 12 to achieve the coherence of the two beams of light. A待测 sensor array 16 is placed at the position of the third image plane 12. The待测 sensor is placed on the first displacement stage 19. The data of the待测 sensor array 16 is read and processed through the upper computer 18, and is used to control the movement of the first displacement stage 19.

[0040] After both the local oscillator light and the signal light pass through the first beam combiner 10, they are first split by the first beam splitter 13. The reflected light is then converged by the seventh lens group 14, forming a real image on the fourth image plane 15, thus achieving coherence between the two beams. A reference sensor array 17 is placed at the position of the third image plane 15. The reference sensor is placed on the second displacement stage 20, and the host computer 18 reads and processes the data from the reference sensor array 17 and controls the movement of the second displacement stage 20.

[0041] The coherent detection sensor array testing platform of this invention splits the light emitted by the light source into signal light and local oscillator light, which are then expanded, collimated, and shaped to make their propagation directions nearly parallel. These are then converged onto the image plane, where the sensor array converts the optical signal into an electrical signal. A motion control module moves the sensor array under test, making the optical path more stable. Finally, the electrical signal is processed in the host computer to obtain the target's velocity and distance information, realizing coherent velocimetry and ranging of the focal plane array. This effectively avoids phase misalignment caused by AC components and improves the signal-to-noise ratio. Using the testing platform of this invention, a testing environment closer to real-world usage conditions can be generated. Furthermore, the effective testing area can cover a large area, allowing for simultaneous testing of the entire array, saving testing time, reducing inconsistencies in the testing environment when switching between different test pixels or testing areas, and improving testing efficiency.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sensor array test platform using coherent detection, characterized in that, It includes a light source (1), an optical lens group, a sensor array, a motion control module, and a host computer (18). The optical lens group divides the laser emitted from the light source (1) into signal light and local oscillator light. The signal light is projected toward the target and expanded after being reflected by the target to form approximately parallel light. The local oscillator light is converged and collimated to form approximately parallel light. The approximately parallel light formed by the signal light and the approximately parallel light formed by the local oscillator light are combined and split, and then converged on two image planes respectively. The signal light and the local oscillator light are coherent on the image planes. After the sensor array is connected to the motion control module, it is placed at the positions of the two image planes respectively. The sensor array converts the optical signal into an electrical signal and transmits it to the host computer (18). The host computer (18) converts the electrical signal into measurement information. The host computer (18) changes the position of the sensor array by controlling the movement of the motion control module. The optical lens group includes 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), where it is collimated, shaped, and split 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, forming a real image on the second image plane (8). The real image is expanded by one of the fifth lens groups and then enters the first beam combiner (10). The local oscillator light is shaped and focused by the third lens group (4) to generate a laser beam waist at the first image plane (5). The laser beam waist is expanded by another fifth lens group and then 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 coherence between the signal light and the local oscillator light on the third image plane (12). Both the signal light and the local oscillator light pass through the first beam combiner (10) and then enter the first beam splitter (13) to split the light into two paths. The first path of light passes through the sixth lens group (11) and forms a first real image on the third image plane (12). At the same time, the second path of light passes through the seventh lens group (14) and forms a second real image on the fourth image plane (15). The sensor array under test (16) and the reference sensor array (17) are placed at the third image plane (12) and the fourth image plane (15), respectively. After the sensor array under test (16) and the reference sensor array (17) complete photoelectric conversion, they input electrical signals to the host computer (18). The motion control module includes a first displacement stage (19) and a second displacement stage (20). The sensor array to be tested (16) is installed on the first displacement stage (19), and the reference sensor array (17) is installed on the second displacement stage (20). Both the first displacement stage (19) and the second displacement stage (20) are connected to the host computer (18).

2. The sensor array test platform using coherent detection as described in claim 1, characterized in that, The host computer (18) is a computer, a microcontroller, or a PLC controller.

3. The sensor array test platform using coherent detection as described in claim 1, characterized in that, The electrical signal can be an analog current signal, an analog voltage signal, or a digital signal.

4. A sensor array test platform using coherent detection as described in claim 1, characterized in that, The measurement information includes the target's distance, target speed, and beat frequency.

5. A sensor array test platform using coherent detection as described in claim 1, characterized in that, The sensor array is a photodiode array.

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