A test device and method for time stability of a streak tube laser radar detector

Abstract

The application discloses a kind of test device of the stability of stripe tube laser radar detector with time, the device includes pulse signal trigger, host computer, laser collimation device and laser signal stripe tube imaging device, wherein: laser collimation device is constituted by laser and collimation system, and laser signal stripe tube imaging device is constituted by stripe tube detector and CCD camera.By the laser beam after collimation through stripe tube detector, the laser spot image obtained is stored into host computer using CCD camera, a large number of image data is stored by long-time running of the device, and then the offset of the centroid position of spot image with the working time of test device is analyzed by centroid extraction and other processing methods to achieve the purpose of testing the stability of stripe tube detector with time.The application can accurately collimate light beam, realize mode switching, ensure normal operation of each device of the system, and effectively test the stability of stripe tube detector.

Description

Technical Field

[0001] This invention belongs to the field of real-time image processing and relates to a device and method for testing the stability of a stripe tube detector in a stripe tube imaging lidar. Background Technology

[0002] LiDAR, due to its high precision and all-weather operation, is widely used in military and civilian fields. However, traditional LiDAR has some limitations, such as insufficient image clarity of targets and the need to improve anti-interference capabilities. Against this backdrop, Streak Tube Imaging Lidar (STIL) has emerged. A streak tube detector is a vacuum optoelectronic imaging device based on the external photoelectric effect and microchannel plate low-light imaging. It has shaping and focusing functions for high-speed moving electrons, which can greatly improve image quality and enhance the detection performance of LiDAR.

[0003] In a stripe tube imaging lidar system, the stability of the stripe tube detector is crucial. Stripe tube imaging lidar is typically used to measure parameters such as the distance and velocity of a target. The stability of the stripe tube detector is closely related to the measurement accuracy. When the stripe tube detector is stable, the characteristics of the laser beam (such as wavelength and intensity) remain stable, allowing for more accurate measurement using the information returned after the laser signal interacts with the target. If the stripe tube detector is unstable, parameters such as the propagation direction and intensity distribution of the laser beam will change. For example, even a slight vibration of the stripe tube detector may cause a shift in the optical axis of the laser beam, resulting in a blurred image on the imaging plane. Just like a blurry photograph when the camera shakes, this severely affects the imaging quality of the lidar on the target object, making subsequent target identification, classification, and measurement impossible to perform accurately. Summary of the Invention

[0004] To address the critical importance of the stability of the streak tube detector in streak tube imaging lidar for measurement accuracy, this invention provides a testing device and method for the time-varying stability of streak tube lidar detectors. The stability of the streak tube is tested by processing the image data of the laser signal passing through it. This invention involves passing a collimated laser beam through the streak tube detector, then using a CCD camera to capture and store the laser spot image in a host computer. The device operates for an extended period, storing a large amount of image data. Subsequently, methods such as centroid extraction are used to analyze the shift in the centroid position of the spot image over the operating time of the testing device, thereby achieving the purpose of testing the time-varying stability of the streak tube detector. This invention can accurately collimate the beam, achieve mode switching, ensure the normal operation of all components in the system, and effectively test the stability of the streak tube detector.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A testing device for the time-varying stability of a stripe tube lidar detector includes a pulse signal trigger, a host computer, a laser collimation device, and a laser signal stripe tube imaging device, wherein:

[0007] The laser collimation device consists of a laser and a collimation system. The laser beam generated by the laser is processed by the collimation system to form a high-quality, highly collimated parallel laser beam.

[0008] The collimation system is a collimation structure consisting of a first aperture, a collimating lens group, and a second aperture, which is called an "aperture-collimating lens group-aperture". The laser beam generated by the laser through the trigger pulse first passes through the first aperture to remove stray light at the edge; then it passes through the collimating lens group to collimate the diverging laser beam into a parallel beam; and then it passes through the second aperture to optimize the intensity distribution of the beam. The second aperture is located close to the stripe tube detector to reduce beam divergence and reduce the impact of changes in the intensity distribution of the laser spot.

[0009] The laser signal stripe tube imaging device consists of a stripe tube detector and a CCD camera. The stripe tube detector images laser pulses into stripe images and switches the working mode through a scanning circuit. The CCD camera receives the stripe images transmitted by the stripe tube detector and transmits the acquired image data to the host computer.

[0010] The pulse signal trigger is used to provide trigger pulses to the laser, stripe tube scanning circuit, and CCD camera through different channels;

[0011] The host computer is used to control the pulse signal trigger to control the frequency and delay of the trigger pulses output by different channels, receive laser signal image data collected by CCD camera and perform centroid extraction processing on the image data, and obtain the laser beam offset with the working time of the test device by analyzing the offset of the centroid position in the X and Y axes of the image with the working time of the test device, and test the stability of the stripe tube detector over time.

[0012] A method for testing the time-varying stability of a stripe tube lidar detector includes the following steps:

[0013] Step 1: Generate laser pulses: The host computer controls the pulse signal trigger to input trigger pulses to the laser in the laser collimation system, thereby generating laser pulses.

[0014] Step 2: Collimate the laser pulse using a collimation system: Use the collimation system in the laser collimation device to collimate the laser beam output from the laser to ensure that it has good directionality and parallelism before entering the stripe tube detector.

[0015] Step 3: Timing control of stripe tube detector scanning circuit and CCD camera: Use the host computer to manipulate the pulse signal trigger to input trigger pulses to the stripe tube detector scanning circuit and CCD camera respectively, and accurately set the trigger pulse frequencies input to the laser, stripe tube detector scanning circuit and CCD camera to match each other. At the same time, set different trigger pulse delays according to imaging requirements.

[0016] Step 4: Acquisition of laser pulse stripe image: The trigger pulse provided by the pulse signal trigger enables the laser collimation device and the laser signal stripe tube imaging device to work normally. After the collimated laser beam passes through the laser signal stripe tube imaging device, it is output as a two-dimensional stripe image. The light spots in the stripe image correspond one-to-one with the laser pulse information.

[0017] Step 5: Laser Pulse Stripe Image Processing: The laser pulse stripe image acquired by the CCD camera is transmitted to the host computer for centroid extraction. The stability of the stripe tube detector over time is determined based on the shift of the spot centroid position as the test device operates. The stability of the stripe tube detector under different operating modes is tested through the design of the scanning circuit. The operating mode switching method of the stripe tube detector includes: adding a scanning circuit to both ends of the deflection electrode of the stripe tube detector. A switch is designed at one end of the scanning circuit and the other end is grounded. When the switch is connected to the positive terminal of the power supply, there is a deflection voltage between the deflection electrodes, and the stripe tube detector switches to dynamic mode; when the switch is connected to the ground wire, the voltage between the deflection electrodes is zero, and it switches to static mode.

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

[0019] 1. This invention controls the laser, stripe tube detector scanning circuit, and CCD camera separately through different channels of the pulse generator, ensuring that the devices can work normally when the laser generated by the trigger pulse passes through the various devices of the system.

[0020] 2. This invention, through a system of "aperture-collimating lens group-aperture", can precisely collimate a laser beam into a uniform, focused, and parallel beam;

[0021] 3. This invention achieves easy switching of the working mode of the stripe tube detector through the design of the scanning circuit of the stripe tube detector. Attached Figure Description

[0022] Figure 1 A schematic diagram of a device module for testing the stability of a stripe tube detector in a stripe tube imaging lidar.

[0023] Figure 2 A schematic diagram of a device for controlling the operating mode of the stripe tube detector in a stripe tube imaging lidar. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0025] Specific Implementation Method 1: This implementation method provides a testing device for the time-varying stability of a stripe tube lidar detector, such as... Figure 1 As shown, the testing device includes a pulse signal trigger, a host computer, a laser collimation device, and a laser signal stripe tube imaging device, wherein:

[0026] The pulse signal trigger is controlled by a host computer and has multiple channels. The host computer can control the frequency and delay of the trigger pulses of each channel. The trigger pulses generated by different channels of the pulse signal generator are used to trigger the laser, the stripe tube detector scanning circuit, and the CCD camera, respectively. The trigger pulses with different frequencies and delays can enable the stripe tube detector to image at the optimal time, control the camera's exposure time to fully acquire the image information of the laser pulse, avoid overexposure or underexposure, and reduce laser interference to the camera.

[0027] The host computer is used to control the pulse signal trigger, receive images acquired by the CCD camera, and perform processing and analysis such as centroid extraction on the images to obtain the centroid position of the image. By analyzing the offset of the centroid position in the image on the X and Y axes as the test device operates, the offset of the laser beam as the test device operates is obtained, thereby achieving the purpose of testing the stability of the stripe tube detector.

[0028] The laser collimation device consists of a laser, an aperture, and a collimating lens group. It utilizes an aperture-collimating lens group-aperture collimation structure to remove stray light from the laser beam output by the laser, collimating the laser beam into a uniform, focused parallel laser beam. The specific process of achieving the collimation effect is as follows: The laser generates laser light through a trigger pulse. The laser pulse passes through the aperture for the first time, removing stray light at the edges and reducing unnecessary interference light, making the laser purer. The collimating lens group then collimates the diverging laser beam into a parallel beam with almost no change in propagation direction. Finally, the laser passes through a second aperture, which optimizes the intensity distribution of the beam, making the laser entering the streak detector have a more uniform intensity across the cross-section. Furthermore, the second aperture is closer to the streak detector, resulting in a shorter propagation distance before the beam enters the detector, reducing beam divergence and allowing for more precise control of the beam shape and size entering the streak detector, thus reducing the interference of laser spot intensity distribution variations on the imaging effect.

[0029] The laser signal stripe tube imaging device mainly consists of a stripe tube detector and a CCD camera. The collimated laser light is focused onto the photocathode of the stripe tube detector, generating photoelectrons that convert the optical signal into an electronic signal. These photoelectrons are accelerated and focused by a grid to form a beam. Deflection electrodes deflect the electron beam over time and space before it is emitted onto a fluorescent screen for imaging. The image on the fluorescent screen of the stripe tube detector is enhanced by a microchannel plate and coupled to the CCD camera sensor array via a fiber optic taper. The CCD camera sensor then transmits the acquired image data to a host computer.

[0030] The process of the stripe tube detector switching operating modes through the scanning circuit is described in [reference]. Figure 2 The operating mode switching method needs to be described in conjunction with the process of stripe tube imaging to stripe image. The imaging process of the laser signal in the stripe tube detector includes:

[0031] B1: When the laser light signal enters the stripe tube detector, it is first received by the photocathode of the stripe tube detector. Under the induction of the light signal, the photocathode generates photoelectrons, thereby completing the process of converting the light signal into an electronic signal.

[0032] B2: The photoelectrons emitted from the photocathode are focused and accelerated by the grid of the stripe tube detector to form a photoelectron beam. The stripe tube detector uses a control mechanism to focus and accelerate the photoelectrons into a beam.

[0033] B3: The photoelectron beam output from the focused electrode is scanned and deflected by the deflection electrodes of the streak tube detector. The deflection electric field controls the position of the photoelectrons to spatially deflect linearly with the incident time as they leave the field. After deflecting away from the electric field, the photoelectrons strike the fluorescent screen of the streak tube detector and form an image. This image is enhanced by a microchannel plate, and the CCD camera receives the enhanced image data and transmits it to the host computer for processing. Therefore, this part is the key area for controlling the photoelectron beam deflection, and the scanning circuit is connected to both ends of the deflection electrodes of the streak tube detector.

[0034] Interface A1 is the connection point that provides voltage to the deflection electrodes of the stripe tube detector. When the switch of the scanning circuit is connected to interface A1, there is a voltage between the two deflection electrodes, and the stripe tube detector is in dynamic operating mode. Interface A2 is the connection point that connects the stripe tube detector to ground. When the switch of the scanning circuit is connected to interface A2, the voltage between the two deflection electrodes is zero, and the stripe tube detector is in static operating mode. Therefore, the operating mode of the stripe tube detector can be changed by changing the interface to which the scanning circuit switch is connected.

[0035] The multiple trigger pulses in this invention have frequency matching and different delays; the delay of the CCD camera is set to be greater than the delay of the laser, and the delay of the stripe tube scanning circuit is slightly greater than the delay of the CCD camera, depending on the position of each device.

[0036] Specific Implementation Method Two: This implementation method provides a method for testing the time-dependent stability of a stripe tube lidar detector. The method uses a trigger pulse output from a pulse signal trigger to control the delay of the laser, stripe tube detector, and CCD camera; it utilizes a collimating lens group as the laser collimation system; before the laser incident on the stripe tube detector, the laser passes through an "aperture-collimating lens group-aperture" structure to collimate it into a high-quality, highly collimated parallel laser beam; and switches are designed in the scanning circuits at both ends of the stripe tube detector to switch the detector's operating mode. The specific steps are as follows:

[0037] Step 1: Generate laser pulses: The host computer controls the pulse signal trigger to input trigger pulses to the laser, thereby generating laser pulses;

[0038] Step 2: Collimating the laser pulse using a laser collimation device: Before the laser pulse output from the laser enters the streak tube detector, it needs to be collimated. Therefore, a "stop-collimating lens group-stop" structure is designed and placed between the laser and the streak tube detector. The stop, through which the laser passes for the first time, removes stray light from the edges and uneven intensity distribution; the collimating lens group collimates the diverging laser signal into a parallel laser signal; the stop, through which the laser passes for the second time, further optimizes the beam uniformity and reduces the impact of variations in laser spot intensity distribution. By adjusting the positions of the lens group and the stop, the laser is precisely collimated before entering the streak tube detector, producing a high-quality, highly collimated parallel laser beam.

[0039] Step 3: Timing Control of the Stripe Detector Scanning Circuit and CCD Camera: The host computer manipulates other channels of the pulse signal trigger to input trigger pulses to the stripe detector scanning circuit and CCD camera respectively. The trigger pulse frequencies input to the laser, stripe detector scanning circuit, and CCD camera are set to be matched, with different delays. Since the laser pulse output from the laser passes through the stripe detector before entering the CCD camera during the implementation of this invention, the delay time of the trigger pulse input to the CCD camera is set to be greater than the delay time of the trigger pulse input to the laser, and the delay time of the trigger pulse input to the stripe detector scanning circuit is slightly greater than the delay time of the trigger pulse input to the CCD camera, to ensure that the CCD camera can receive the image data transmitted by the stripe detector relatively completely.

[0040] Step 4: Image Data Acquisition and Processing: The stripe image generated by the laser pulse through the stripe tube detector is acquired by the CCD camera, which then sends the acquired image data to the host computer. The host computer processes the acquired image data using methods such as centroid extraction. The deviation of the laser beam over the working time of the testing device is observed to achieve the purpose of testing the stability of the stripe tube over time.

[0041] In this invention, the stripe tube detector has two operating modes: dynamic and static. These two modes can be switched by the presence or absence of voltage between the deflection electrodes controlled by the scanning circuit at both ends of the stripe tube detector. In dynamic mode, the stripe tube detector can quickly respond to and scan light signals, therefore, the stability of the stripe tube detector in different operating modes is important. This invention adds a switch to one end of the scanning circuit and grounds the other end. When the switch is connected to the positive terminal of the power supply, a voltage exists between the deflection electrodes, which can switch the operating mode of the stripe tube detector from static to dynamic. Similarly, when the switch is connected to the ground wire at the other end of the scanning circuit, the voltage between the deflection electrodes is zero, which can switch the operating mode of the stripe tube detector from dynamic to static, thereby realizing the switching of the stripe tube detector's operating mode.

Claims

1. A test device for the temporal stability of a streak tube lidar probe, characterized in that The device comprises a pulse signal trigger, a host computer, a laser collimation device and a laser signal streak tube imaging device, wherein: The laser collimation device is composed of a laser and a collimation system, and the laser beam generated by the laser is processed by the collimation system to form a parallel laser beam with high quality and high collimation degree; The collimation system is a "aperture-collimation lens group-aperture" collimation structure composed of a first aperture, a collimation lens group and a second aperture, the laser beam generated by the laser through the trigger pulse first passes through the first aperture to remove the stray light at the edge; then the divergent laser beam is collimated into a parallel light beam by the collimation lens group; and then the second aperture is passed through to optimize the light intensity distribution of the light beam, and the second aperture is close to the streak tube detector; The laser signal streak tube imaging device is composed of a streak tube detector and a CCD camera, the streak tube detector images the laser pulse into a streak image, and the working mode is switched through a scanning circuit; the CCD camera receives the streak image transmitted by the streak tube detector and transmits the collected image data to the host computer; The pulse signal trigger is used to trigger the pulse, and the trigger pulse is provided to the laser, the streak tube scanning circuit and the CCD camera through different channels; The delay of the CCD camera is greater than that of the laser, and the delay of the streak tube scanning circuit is greater than that of the CCD camera; The host computer is used to control the pulse signal trigger to control the frequency and delay of the trigger pulse output by different channels, receive the laser signal image data collected by the CCD camera and perform centroid extraction processing on the image data, analyze the offset of the centroid position in the image along the X axis and Y axis with the working time of the test device, obtain the offset of the laser beam with the working time of the test device, and test the stability of the streak tube detector with time.

2. A method for testing the temporal stability of a streak tube lidar detector using the apparatus of claim 1, characterized in that The method comprises the following steps: Step one, generating a laser pulse: the host computer controls the pulse signal trigger to input a trigger pulse to the laser in the laser collimation system, so as to generate a laser pulse; Step two, collimating the laser pulse by using the collimation system: the collimation system in the laser collimation device is used to collimate the laser beam output from the laser, so as to ensure that it has good directivity and parallelism before entering the streak tube detector; Step three, time sequence control of the streak tube detector scanning circuit and the CCD camera: the host computer is used to control the pulse signal trigger to input trigger pulses to the streak tube detector scanning circuit and the CCD camera respectively, and the trigger pulse frequency input to the laser, the streak tube detector scanning circuit and the CCD camera is accurately set to match each other, and different trigger pulse delays are set according to the imaging requirements; Step four, laser pulse streak image acquisition: the trigger pulse provided by the pulse signal trigger makes the laser collimation device and the laser signal streak tube imaging device work normally, and the collimated laser beam is output as a two-dimensional streak image after passing through the laser signal streak tube imaging device, and the light spot in the streak image corresponds to the laser pulse information one by one. Step five, laser pulse fringe image processing: the laser pulse fringe image collected by the CCD camera is transmitted to the host computer for centroid extraction processing, the stability of the streak tube detector over time is judged according to the offset amount of the spot centroid position over the working time of the test device, and the stability of the streak tube detector under different working modes is tested through the design of the scanning circuit.

3. The method of testing the stability over time of a streak tube lidar probe according to claim 2, characterized in that In step five, the working mode switching method of the streak tube detector comprises: adding a scanning circuit at both ends of the deflection electrode of the streak tube detector, designing a switch at one end of the scanning circuit and grounding at the other end; when the switch is connected to the positive pole of the power supply, there is a deflection voltage between the deflection electrodes, and the streak tube detector is switched to the dynamic mode; when the switch is connected to the ground, the voltage between the deflection electrodes is zero, and it is switched to the static mode.

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