Optoelectronic Payload Three-Axis On-Line Calibration System

Abstract

The three-axis on-line calibration system for optoelectronic payloads of the present invention belongs to the field of optoelectronic detection and at least partially solves the technical problem of low calibration efficiency of existing systems for visible light, laser and infrared. It realizes three-axis on-line calibration through two steps: adjusting the optical axis position of the television camera according to the imaging position of the laser emission spot on the television camera, and adjusting the optical axis position of the infrared thermal imager according to the imaging positions of the target on the television camera and the infrared thermal imager. Among them, the television camera has three imaging bands switched by filters, namely color, black and white, and spot monitoring. During reconnaissance, it works in the color and black and white bands, and during on-line calibration, it works in the spot monitoring band. When the television camera aims at the target and starts laser irradiation, the spot monitoring band can image the laser spot position and the target at the same time, calculate the offset, and after adjusting the electronic cross of the television camera, the optical axis calibration of the television camera and the laser illuminator is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic detection, and particularly relates to an on-line calibration system for three optical axes of an optoelectronic payload. Background Art

[0002] During the process of a laser guidance system performing an attack mission, first, a television camera, an infrared thermal imager, etc. are used to comprehensively detect and identify a target. After confirming that the target is a target to be attacked, a laser illuminator is used to emit a laser beam to continuously irradiate the target. After a laser-guided weapon is launched, it enters the target scattered laser field, and a four-quadrant detector of a seeker guides the laser-guided weapon to strike the target. For an optoelectronic pod, stress is released, and there is a deviation in the optical axis. The deviation is caused by factors such as airborne vibration, temperature, and pressure.

[0003] As Figure 1 As shown, when the optoelectronic payload aims at a target, the deviation α between the three optical axes, and the deviation α means that there are deviations in visible light, laser, and infrared, resulting in an error between the center of the laser spot and the center of the target.

[0004] In the prior art methods, such as the one with the publication number (CN110823527 A), three-axis calibration is performed before leaving the factory. The optical axis deviation between the television camera and the laser illuminator is denoted as αTV, and the optical axis deviation between the infrared thermal imager and the laser illuminator is denoted as αIR. After calibration, both need to be less than 0.1 mrad. However, after leaving the factory, due to environmental changes such as vibration and temperature, stress release and aggregation cause optical axis deviation, and this method cannot be used for on-line calibration.

[0005] For example, the Sniper pod announced in US 6359681 B1 and the ATFLIR pod announced in US 6288381 B1 both achieve on-line calibration by moving units such as scanning mirrors / prisms / wedge prisms in the optical path and inserting a reference target optical path. The related configurations are complex, the volume is large, and the cost is high, which is not conducive to application in optoelectronic payloads. Summary of the Invention

[0006] In view of this, the present invention provides an on-line calibration system for three optical axes of an optoelectronic payload, which at least partially solves the technical problem of low calibration efficiency of the existing system for visible light, laser, and infrared.

[0007] An on-line calibration system for three optical axes of an optoelectronic payload is provided, which is applicable to the three-axis calibration of television, infrared, and laser of an airborne optoelectronic pod. It is installed on an azimuth and elevation motion platform and includes a laser illuminator, an infrared thermal imager, and a television camera. A target is installed at a preset distance from the pod, and the target is provided with a first mark, wherein:

[0008] The television camera is successively provided with a front fixed group, a zoom group, a compensation group, a rear fixed group and a filter along the optical path transmission direction, and the filter is used for switching the transmitted wavelength band or switching colors;

[0009] An image plate is arranged on the azimuth axis system in the optoelectronic pod. The image plate is provided with a second infrared mark and a third television mark. The shapes of the second mark and the first mark are the same. The video output centers of the infrared thermal imager and the television camera pass through the image plate and are received by the display and control console;

[0010] The television camera aims at the first mark of the target and starts laser irradiation. The laser spot monitoring wavelength band of the television camera can simultaneously image the position of the laser spot and the first mark of the target. The first offset is calculated through the image plate, and the first offset is fed back to the main controller. The main controller instructs the third mark on the image plate to be adjusted according to the first offset, and the azimuth and elevation motion platform drives the television camera to aim at the center of the first mark of the target;

[0011] Determine the second offset between the first mark and the second mark in the imaging screen of the infrared thermal imager. The second offset is fed back to the main controller. Moreover, the main controller instructs the second mark on the image plate to move according to the second offset, and after the movement, the centers of the first mark and the second mark coincide.

[0012] The technical beneficial effects of the present invention are as follows:

[0013] For the two steps of calibrating the optical axis deviation between the television camera and the laser illuminator and calibrating the optical axis deviation between the infrared thermal imager and the laser illuminator, the beneficial effects are as follows:

[0014] 1. The television camera, the infrared thermal imager and the laser illuminator are all independent devices, which can be designed separately, are easy to assemble and have high maintainability;

[0015] 2. The electrical cross of the television camera and the infrared thermal imager can be adjusted, and the three optical axes can be calibrated online during flight;

[0016] 3. Through the laser spot monitoring wavelength band, the whole process of laser irradiation can be archived, which is beneficial for post-event evaluation or analysis. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings required in the embodiments. Obviously, the following-described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0018] Figure 1 It is a schematic diagram of laser irradiation error caused by three-optical-axis deviation;

[0019] Figure 2 is the optoelectronic payload system of the present invention;

[0020] Figure 3 is the flowchart of the on-line calibration of the three optical axes of the optoelectronic payload of the present invention;

[0021] Figure 4 is the composition diagram of the television camera;

[0022] Figure 5 is the diagram of the filter switching mechanism;

[0023] Figure 6 is the schematic diagram of the change of the image deviation corresponding to the on-line calibration process of the three optical axes. Specific embodiments

[0024] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0025] The following illustrates the embodiments of the present disclosure through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts belong to the scope of protection of the present disclosure.

[0026] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present disclosure, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, this device and / or this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0027] Such as Figure 2The three-axis on-line calibration system for optoelectronic payloads is applicable to the three-axis calibration of television, infrared, and laser in airborne optoelectronic pods. It is installed on an azimuth and elevation motion platform. The system includes a laser illuminator, an infrared thermal imager, and a television camera. A target is installed at a preset distance from the pod, and the preset distance is subject to the actual test distance. The target is provided with a first mark, where:

[0028] In the television camera, an optical lens group in the prior art is sequentially arranged along the optical path transmission direction, such as Figure 4 shown. From the object surface to the image surface (taking the Figure 4 placement direction as a reference, from left to right), a front fixed group 1 (a combination of multiple lenses satisfies: positive optical power), a zoom group 2 (a combination of multiple lenses satisfies: negative optical power), a compensation group 3 (a combination of multiple lenses satisfies: positive optical power), and a rear fixed group 4 (a combination of multiple lenses satisfies: positive optical power) are sequentially arranged. And it also includes a protective lens 6 and a filter 5 with a switchable transmission band. For example, by switching the filter 5, there are three imaging bands: color (400 - 700nm), black and white (700 - 900nm), and laser spot monitoring (1064 ± 50nm). That is, the filter 5 includes a filter 24, a filter 25, and a filter 26, which has the function of being able to observe the laser. The specific installation structure is as Figure 5 shown, including a mounting plate 21. There is an opening in the central area of the mounting plate 21. On one side of the mounting plate 21, a filter target wheel is installed. The filter target wheel includes an integrally formed target wheel part 22 and a gear part 27. Three mounting holes are spaced on the target wheel part 22, and a filter 24 for color (400 - 700nm) monitoring, a filter 25 for black and white (700 - 900nm) monitoring, and a filter 26 for laser spot monitoring (1064 ± 50nm) are respectively installed. And the gear part 27 meshes with a driving gear 23, and the driving gear 23 is driven by a motor (not marked in the figure). The motor is controlled by a controller. Driven by the motor, the driving gear 23 rotates, so as to adjust one of the filter 24, the filter 25, and the filter 26 to block the hole opened in the central area of the mounting plate 21, for calibrating the visible light, laser, and infrared.

[0029] Furthermore, the image processing machine interacts with a monitor with a display screen, and the image processing machine interacts with an image board set in the azimuth axis system in the optoelectronic pod. The image board on the image processing machine is provided with a second mark for infrared and a third mark for television. The shapes of the second mark and the first mark are the same. For example, they are both cross-shaped cursors. The video output centers of the infrared thermal imager and the television camera are received by the display control console through the image board;

[0030] The television camera aims at the first mark of the target and activates the laser irradiation. The light spot monitoring band of the television camera simultaneously images the position of the laser light spot and the first mark of the target, determines the offset between the laser light spot and the first mark, and calculates the first offset through the image plate. The first offset is fed back to the main controller, and the main controller instructs the third mark (e.g., the electrical cross) on the image plate to be adjusted according to the first offset. For example, the azimuth and elevation motion platform drives the television camera to aim at the center of the first mark of the target;

[0031] Adjustment of the infrared, such as determining the second offset between the first mark and the second mark in the imaging screen of the infrared thermal imager. The second offset is fed back to the main controller, and moreover, the main controller instructs the second mark on the image plate to move according to the second offset. After the movement, the centers of the first mark and the second mark coincide, and the data processed by the image processor is transmitted to the monitor, and the monitor is displayed through the display, such as Figure 6 As shown, the image processor performs accurate display during the calibration of visible light, laser, and infrared.

[0032] As a specific implementation provided in this case, the azimuth and elevation motion platform in the prior art has two motion axes of azimuth and elevation, and can adjust the aiming directions of the television sensor, laser sensor, and infrared sensor. The method for the display console to adjust the second mark and the third mark includes:

[0033] The calibration process is default to be carried out under the minimum field of view, and the field of view calibration amount satisfies:

[0034] FOV TV / IR / NFOV TV / IR ×α TV / IR , where, NFOV TV / IR is the minimum field of view of the television and infrared, FOV TV / IR is the calibration field of view of the television and infrared, and NFOV TV / IR is the angle calibration amount under the minimum field of view of the television and infrared. All calibration amounts are rounded to the nearest pixel during actual implementation.

[0035] See Figure 1 , the system of this case includes a laser illuminator, an infrared thermal imager, a television camera, an azimuth and elevation motion platform, a system control component, and an image processor; the three optoelectronic sensors are installed on the azimuth and elevation motion platform. The azimuth and elevation motion platform has two motion axes of azimuth and elevation, and can drive the optoelectronic sensors to move in the azimuth and elevation directions to aim at the target. The image processor can calculate the target position and the light spot position and output them to the system control component.

[0036] Please refer to Figure 5 , the electrical cross representing the optical axis at the video output center of the infrared thermal imager and the television camera can be adjusted through the system control component.

[0037] It includes the following usage steps:

[0038] (1) Start the online calibration mode;

[0039] (2) Aim the TV camera at the target, and the display screen in the monitor shows the state as shown in the upper left in Figure 6 the figure;

[0040] (3) The laser illuminator emits pulses, the TV camera enters the light spot monitoring band, and the display screen in the monitor shows the state as shown in the middle left in Figure 6 the figure;

[0041] (4) The image processor calculates the deviation between the laser light spot and the optical axis center (electrical cross position) of the TV camera;

[0042] (5) The system control component adjusts the optical axis center (electrical cross position) of the TV camera, and the compensated image shows the state as shown in the lower left in Figure 6 the figure;

[0043] (6) The TV camera aims at the target again, and the display screen in the monitor shows the state as shown in the lower right in Figure 6 the figure;

[0044] (7) Switch to the infrared thermal imager video display and output, and the display screen in the monitor shows the state as shown in the middle right in Figure 6 the figure;

[0045] (8) The image processor calculates the deviation between the laser light spot and the optical axis center (electrical cross position) of the infrared thermal imager;

[0046] (9) The system control component adjusts the optical axis center (electrical cross position) of the infrared thermal imager, and the compensated image shows the state as shown in the upper right in Figure 6 the figure;

[0047] (10) Store the adjusted optical axis center of the infrared thermal imager and the optical axis center of the TV camera;

[0048] (11) End the online calibration.

[0049] The above calibration process is default to be carried out under the minimum field of view, and the calibration amount for other fields of view can be calculated by the following formula:

[0050] FOV TV / IR / NFOV TV / IR ×α TV / IR NFOV TV / IR is the minimum field of view of the TV and infrared, FOV TV / IR is the calibration field of view of the TV and infrared, α TV / IR is the angle calibration amount under the minimum field of view of the TV and infrared. All calibration amounts are rounded to the nearest pixel during actual implementation. All calibration amounts are rounded to the nearest pixel during actual implementation.

[0051] Before performing the striking task after calibration is completed, the TV camera can be switched to the laser spot monitoring band to confirm the irradiation accuracy and improve the task success rate.

[0052] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present disclosure should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. An on-line calibration system for three optical axes of an optoelectronic payload, applicable to the calibration of three optical axes of television, infrared and laser in an airborne optoelectronic pod, installed on an azimuth and elevation motion platform, characterized in that, It includes a laser illuminator, an infrared thermal imager and a television camera. A target is installed at a preset distance from the pod, and the target is provided with a first mark, where: Inside the television camera, a front fixed group, a zoom group, a compensating group, a rear fixed group and a filter are sequentially arranged from the object plane to the image plane, and the filter is used for switching the transmitted wavelength bands; An image processor is arranged on the azimuth axis system inside the optoelectronic pod. The image processor includes an image board, and the image board is provided with a second mark for infrared and a third mark for television. The shapes of the second mark and the first mark are the same. The video output centers of the infrared thermal imager and the television camera pass through the image board and are received by the display control console; The television camera aims at the first mark of the target and starts laser irradiation. The spot monitoring wavelength band of the television camera can simultaneously image the position of the laser spot and the first mark of the target. The first offset is calculated through the image board, and the first offset is fed back to the main controller. The main controller instructs the third mark on the image board to be adjusted according to the first offset. Moreover, the azimuth and elevation motion platform drives the television camera to aim at the center of the first mark of the target. Among them, the azimuth and elevation motion platform has two motion axes of azimuth and elevation, and can adjust the aiming directions of the television sensor, the laser sensor and the infrared sensor; Determine the second offset between the first mark and the second mark in the imaging picture of the infrared thermal imager. The second offset is fed back to the main controller. Moreover, the main controller instructs the second mark on the image board to move according to the second offset, and after moving, the centers of the first mark and the second mark coincide. Among them, the method for the display control console to adjust the second mark and the third mark includes: The calibration process is defaultly carried out under the minimum field of view, and the field of view calibration amount satisfies: FOV TV / IR / NFOV TV / IR ×α TV / IR , where, NFOV TV / IR is the minimum field of view of TV and infrared, FOV TV / IR is the calibrated field of view of TV and infrared, and α TV / IR is the angle calibration amount under the minimum field of view of TV and infrared.

2. The three-axis on-line calibration system for optoelectronic payload according to claim 1, characterized in that, The filter is used for switching among the color wavelength band, the black-and-white wavelength band and the laser spot wavelength band.

3. The on-line calibration system for three optical axes of an optoelectronic payload according to claim 2, characterized in that The color wavelength band switched by the filter is 400 - 700 nm, the black-and-white wavelength band is 700 - 900 nm, and the laser spot wavelength band is 1064 ± 50 nm.

4. The three-axis on-line calibration system for optoelectronic payload according to claim 1, characterized in that Both the second mark and the third mark are cross-shaped cursors.

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