Multi-channel imaging camera channel alignment accuracy testing device and method

Abstract

The application discloses a kind of multi-channel imaging camera channel alignment precision testing device and method, solve the technical problems such as high precision requirement of existing test method based on rotary table and collimator, high test cost, low test efficiency.The testing device includes light source, target, collimator, camera support, angle measurement component and acquisition processing module;Light source is installed in the light inlet end of collimator, target is installed between light source and collimator, and is located at the focal plane of collimator;The bottom of collimator is provided with attitude adjusting device;Camera support is used to install the multi-channel imaging camera to be measured;Angle measurement component includes cube mirror and goniometer, and the angle change information of collimator is obtained by cooperation;Acquisition processing module acquires the angle change information obtained by goniometer and the target pattern information obtained by the multi-channel imaging camera to be measured, calculates and outputs the parameter information of the channel alignment precision of the multi-channel imaging camera to be measured.

Description

Technical Field

[0001] This invention relates to a testing apparatus for multi-channel imaging cameras, and more specifically to a testing apparatus and method for channel alignment accuracy of multi-channel imaging cameras. Background Technology

[0002] Multi-channel imaging cameras represent an important direction in the development of optical remote sensing technology and are currently widely used in remote sensing mapping, environmental monitoring, geological hazard assessment, land resource exploration, and marine and atmospheric research. Multi-channel imaging cameras can simultaneously acquire image information of targets in multiple spectral bands, including ultraviolet, visible, near-infrared, short-wave infrared, mid-wave infrared, and long-wave infrared, greatly enhancing the camera's ability to identify and quantify ground features.

[0003] Multichannel imaging cameras typically include multichannel area array imaging cameras, TDI line array imaging cameras, and imaging spectrometers. For multichannel imaging cameras with smaller apertures, aperture-separated imaging is usually employed, with each channel having its own independent imaging lens. As the aperture increases, a common aperture design is generally used, where all channels share a single front optical lens. The subsequent optical path combines field-of-view splitting and beam splitting to achieve multichannel imaging. Each channel of a multichannel imaging camera corresponds to multiple spectral bands within the ultraviolet to long-wave infrared range. Considering the push-broom direction during camera operation, the optical fields of view of each channel have strict positional requirements in spatial orientation. The alignment accuracy of each channel in a multichannel imaging camera is a key indicator for ensuring the positional relationship of each channel. The main testing contents include:

[0004] a) Field of view overlap: refers to the degree of overlap between the corresponding optical fields of view of the detectors of each channel of a multi-channel imaging camera. It is used to reflect the size of the overlapping area of ​​the images acquired by each channel, and it determines the effective area of ​​multi-spectral image information fusion that a multi-channel imaging camera can achieve.

[0005] b) Field rotation deviation: refers to the parallelism between the optical fields of view of the area array imaging camera in the row and column direction, the linear array imaging camera in the swath direction, and the imaging spectrometer in the swath direction, and characterizes the relative rotation between the images acquired by each channel detector.

[0006] After the multi-channel imaging camera is integrated and assembled, there may be spatial deviations in the imaging positions between different spectral channels. This will affect the subsequent application of the acquired data and reduce the accuracy of the instrument. Multi-channel alignment accuracy testing aims to ensure the precise spatial alignment of images from each spectral channel, which is crucial for subsequent multi-channel data registration, multispectral data fusion, fine classification of ground features, accurate identification, and target inversion.

[0007] Currently, testing the channel alignment accuracy of multi-channel imaging cameras requires fixing the camera on a precision turntable, projecting a target (such as a star plate or crosshair) onto the focal plane of each channel detector using a collimator, and sequentially moving the target to the pixel position of the center and edge field of view of each channel, while recording the azimuth and elevation angles of the turntable. This method requires the turntable's accuracy to be superior to the pixel angular resolution of the multi-channel imaging camera, which is difficult to guarantee for high-resolution cameras with sub-second pixel angular resolution. Furthermore, high-resolution multi-channel imaging cameras are typically heavy, requiring a high-precision turntable with heavy load capacity, significantly increasing testing costs. In addition, when testing multi-channel imaging cameras with linear array cameras or imaging spectrometers, extracting the target image position is difficult, requiring repeated adjustments to the target position until the target center is perfectly aligned with the imaging direction of the corresponding channel, resulting in low testing efficiency. Summary of the Invention

[0008] The purpose of this invention is to provide a testing device and method for the channel alignment accuracy of a multi-channel imaging camera, which mainly solves the technical problems of existing testing methods based on turntables and collimators, such as high turntable accuracy requirements, high testing costs, and low testing efficiency.

[0009] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0010] A multi-channel imaging camera channel alignment accuracy testing device, characterized by:

[0011] Includes light source, target, collimator, camera bracket, angle measurement components and data acquisition and processing module;

[0012] The light source is installed at the light-incident end of the collimator, and the optical axis of the light emitted from the light source coincides with the central axis of the collimator.

[0013] The target is installed between the light source and the collimator, and is located at the focal plane of the collimator; the target has a target pattern.

[0014] The bottom of the collimator is equipped with an attitude adjustment device for adjusting the attitude of the collimator. During the adjustment process, the light source and the target change synchronously with the attitude of the collimator.

[0015] The camera bracket is used to mount the multi-channel imaging camera under test, positioning it at the light-emitting end of the collimator;

[0016] The angle measurement component includes a cubic mirror and an angle measuring device; the cubic mirror is installed at the light-incident end of the collimator; the angle measuring device is located on the side of the cubic mirror away from the collimator and is used to cooperate with the cubic mirror to obtain the angle change information of the collimator.

[0017] The acquisition and processing module is connected to the angle measuring device and the multi-channel imaging camera under test, respectively. It is used to acquire angle change information obtained by the angle measuring device and target pattern information obtained by the multi-channel imaging camera under test, and calculate and output parameter information of the channel alignment accuracy of the multi-channel imaging camera under test.

[0018] Furthermore, the attitude adjustment device includes three sets of adjustment components, which are arranged in an isosceles triangle at the bottom of the collimator. The two sets of adjustment components located at the base angles of the isosceles triangle are respectively located at the bottom of the end of the collimator closer to the target, and the set of adjustment components located at the apex angle of the isosceles triangle is located at the bottom of the other end of the collimator farther from the target. Each set of adjustment components includes a translation stage and a lifting stage. The translation stage is used to be mounted on the test workbench and can move horizontally relative to the test workbench. The bottom of the lifting stage is connected to the translation stage, and the top is connected to the bottom of the collimator.

[0019] Furthermore, in each set of adjustment components, the bottom of the lifting platform is spherically hinged to the translation platform, and the top is spherically hinged to the bottom of the parallel light tube.

[0020] Furthermore, the angle measuring device is an autocollimator; the target pattern is a crosshair pattern composed of thick and thin lines.

[0021] Meanwhile, the present invention also provides a method for testing the channel alignment accuracy of a multi-channel imaging camera, comprising the following steps:

[0022] Step 1: Assemble the above-mentioned multi-channel imaging camera channel alignment accuracy testing device, and adjust the multi-channel imaging camera under test and the collimator through the camera bracket and attitude adjustment device respectively, so that the center of the entrance pupil of the multi-channel imaging camera under test and the center of the light output end of the collimator are at the same height and coaxial.

[0023] Step 2: Define any one of the channel detectors in the multi-channel imaging camera under test as its reference channel detector, and the rest as the channel detectors under test; then turn on the light source, and adjust the pose of the collimator through the attitude adjustment device so that the target is imaged at the center of the field of view of the reference channel detector after being collimated by the collimator. At this time, clear the reading of the angle measuring device to zero.

[0024] Step 3: Based on the field-of-view position distribution of each channel detector in the multi-channel imaging camera under test, the pose of the collimator is changed sequentially through the attitude adjustment device so that the target is imaged sequentially at the center of the field of view of each channel detector after being collimated by the collimator; at the same time, the angle change information of the collimator is recorded sequentially through the angle measuring device.

[0025] Step 4: Based on the images output by each channel detector and the angle change information recorded by the angle measuring device, the acquisition and processing module calculates the field of view overlap and field of view rotation deviation between each channel detector under test and the reference channel detector, thereby completing the test of the channel alignment accuracy of the multi-channel imaging camera.

[0026] Further, in step 4, the field-of-view overlap between each detector of the channel under test and the reference channel detector is calculated using any of the following methods:

[0027] A1. If the multi-channel imaging camera under test is an area array imaging camera, extract the edge data of the corresponding target pattern from the image output by each channel detector, and obtain the position information of the corresponding target pattern after performing straight line fitting; then, combined with the corresponding angle change information, calculate the field of view overlap between each channel detector under test and the reference channel detector in the X and Y directions respectively.

[0028] A2. If the multi-channel imaging camera under test is a linear array imaging camera or an imaging spectrometer, extract the position information of the corresponding target pattern from the image output by each channel detector, and then calculate the field of view overlap between each channel detector under test and the reference channel detector by combining the corresponding angle change information.

[0029] Furthermore, in step 4, the field-of-view rotation deviation between each detector of the channel under test and the reference channel detector is calculated using any of the following methods:

[0030] B1. If the multi-channel imaging camera under test is an area array imaging camera, calculate the field-of-view rotation deviation between the detector of each channel under test and the reference channel detector in the Y direction.

[0031] B2. If the multi-channel imaging camera under test is a linear array imaging camera or an imaging spectrometer, calculate the field-of-view rotation deviation between the detector of each channel under test and the reference channel detector in the swath width direction.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The multi-channel imaging camera channel alignment accuracy testing device provided by this invention simulates an infinity target by installing a target at the focal plane of a collimator and illuminating it with a light source. During testing, there is no need to precisely adjust the actual rotation angle of the collimator; the collimator's pose can be adjusted using an attitude adjustment device, and the angle measurement component can monitor the collimator's deflection angle in real time. This not only reduces the accuracy requirements of the attitude adjustment device and improves testing efficiency, but also achieves high-precision measurement of the multi-channel imaging camera channel alignment accuracy.

[0034] 2. The attitude adjustment device in the multi-channel imaging camera channel alignment accuracy testing device of the present invention can adjust the orientation angle, pitch angle, horizontal attitude, and height position of the collimator in real time as needed, further improving the measurement efficiency. At the same time, the attitude adjustment device includes three sets of adjustment components, which significantly reduces the testing cost and improves the economy compared with a high-precision turntable.

[0035] 3. The multi-channel imaging camera channel alignment accuracy testing device of the present invention can monitor the rotation angle of the collimator in real time by fixing a cubic mirror and an angle measuring device at the light-incident end of the collimator. This unifies the field of view angles corresponding to different channel detectors of the multi-channel imaging camera under test to the coordinate system of the angle measuring device, thereby improving the measurement accuracy of channel alignment accuracy.

[0036] 4. The multi-channel imaging camera channel alignment accuracy testing method provided by the present invention takes the center of the reference channel detector as the benchmark, and rotates the collimator in sequence so that the target image is sequentially imaged onto the planned field of view positions of different channel detectors of the multi-channel imaging camera under test. The field of view overlap and field of view rotation deviation can be tested at one time, and the testing efficiency is greatly improved.

[0037] 5. The multi-channel imaging camera channel alignment accuracy test method provided by the present invention designs different channel alignment accuracy calculation methods for different types of multi-channel imaging cameras under test. During the calculation process, the position of the target image can be extracted from the image obtained by the corresponding channel detector, and no precise adjustment of the test device is required during extraction. It is particularly suitable for testing large-aperture cameras and can effectively reduce the requirements for the mechanical structure stability of the test device.

[0038] 6. The multi-channel imaging camera channel alignment accuracy test method provided by the present invention is applicable to the calibration of the field overlap and field rotation deviation of linear array imaging cameras, area array imaging cameras and imaging spectrometers with multiple working spectral bands including ultraviolet, visible, short wave, medium wave and long wave. It is particularly suitable for calibrating the positional relationship between the corresponding imaging fields of each channel detector of a large-aperture multi-channel imaging camera. Attached Figure Description

[0039] Figure 1 This is a reference diagram showing the usage status of the multi-channel imaging camera channel alignment accuracy testing device according to Embodiment 1 of the present invention (the acquisition and processing module is not shown).

[0040] Figure 2 This is a schematic diagram of the target structure in Embodiment 1 of the multi-channel imaging camera channel alignment accuracy testing device of the present invention.

[0041] Figure 3 This is a side view of the connection structure of the collimator and attitude adjustment device in Embodiment 1 of the multi-channel imaging camera channel alignment accuracy testing device of the present invention.

[0042] Figure 4 for Figure 3 The left view.

[0043] Figure 5 This is a schematic diagram of the distribution structure of the three sets of adjustment components in Embodiment 1 of the multi-channel imaging camera channel alignment accuracy testing device of the present invention.

[0044] Figure 6 This is a schematic diagram of the field of view distribution of each channel detector in Embodiment 1 of the multi-channel imaging camera channel alignment accuracy test method of the present invention.

[0045] Figure 7 These are schematic diagrams of target images from different types of multi-channel imaging cameras in Embodiments 1 and 2 of the multi-channel imaging camera channel alignment accuracy test method of the present invention; wherein (a) is a schematic diagram of the target image acquired by the area array imaging camera, and (b), (c), and (d) are schematic diagrams of the target images acquired by the line array imaging camera or the imaging spectrometer, respectively.

[0046] The annotations in the attached figures are explained as follows:

[0047] 1-Multi-channel imaging camera under test, 2-Camera bracket, 3-Columnar tube, 4-Target, 5-Light source, 6-Attitude adjustment device, 7-Cube mirror, 8-Angle measuring device, 9-Fine line, 10-Thick line, 11-First electric lifting platform, 12-Second electric lifting platform, 13-Third electric lifting platform, 14-First electric translation stage, 15-Second electric translation stage, 16-Third electric translation stage, 20-Field of view of the first channel detector, 21-Field of view of the second channel detector, 22-Field of view of the Nth channel detector, 23-Position of the first target image, 24-Position of the second target image, 25-Position of the third target image, 26-Position of the fourth target image. Detailed Implementation

[0048] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0049] Example 1

[0050] This embodiment provides a multi-channel imaging camera channel alignment accuracy testing device. This testing device is suitable for calibrating the field overlap and field rotation deviation of linear array imaging cameras, area array imaging cameras, and imaging spectrometers with multiple working spectral bands including ultraviolet, visible, short wave, medium wave, and long wave. It is particularly suitable for calibrating the positional relationship between the corresponding imaging fields of each channel detector of a large-aperture multi-channel imaging camera.

[0051] like Figure 1As shown, this embodiment takes a multi-channel area array imaging camera as an example. Its corresponding channel alignment accuracy testing device includes a light source 5, a target 4, a collimator 3, a camera bracket 2, an angle measurement component, and an acquisition and processing module.

[0052] Among them, the light source 5 is a uniform light source, which is installed at the light-incident end of the collimator 3, and the optical axis of the light emitted from the light source 5 coincides with the central axis of the collimator 3.

[0053] Reference Figure 1 and Figure 2 The target 4 is circular in shape and is installed between the light source 5 and the collimator 3, located at the focal plane of the collimator 3. Generally, the aperture of the light-emitting end of the light source 5 is larger than the size of the target 4. The target 4 has a target pattern, which is a crosshair pattern composed of thick lines 10 and thin lines 9, with the center of the crosshairs located at the center of the target 4. In this embodiment, the test target 4 is installed at the focal plane of the collimator 3 and illuminated by a uniform light source to simulate a target at infinity.

[0054] The collimator 3 has an attitude adjustment device 6 at its bottom, which is used to adjust the attitude of the collimator 3 to simulate targets at infinity in different fields of view. During the attitude adjustment of the collimator 3, the light source 5 and the target 4 change synchronously with the attitude of the collimator 3.

[0055] Reference Figure 3 , Figure 4 , Figure 5 As shown, the attitude adjustment device 6 includes three sets of adjustment components, which are arranged in an isosceles triangle at the bottom of the collimator 3. Two sets of adjustment components located at the base angles of the isosceles triangle are respectively located at the bottom of the collimator 3 near the target 4, and one set of adjustment components located at the apex angle of the isosceles triangle is located at the bottom of the collimator 3 away from the target 4. Each set of adjustment components includes a translation stage and a lifting stage. The translation stage is mounted on the test workbench and can move horizontally relative to the test workbench in the X direction. The bottom of the lifting stage is spherically hinged to the translation stage to counteract the torsion caused by controlling the translation stage to rotate the collimator 3 in azimuth angle. The top of the lifting stage is spherically hinged to the bottom of the collimator 3. The attitude adjustment device 6 can adjust the azimuth angle, horizontal position, pitch angle, and vertical height of the collimator 3.

[0056] In this embodiment, the translation stage includes a first electric translation stage 14, a second electric translation stage 15, and a third electric translation stage 16, and the lifting stage includes a first electric lifting stage 11, a second electric lifting stage 12, and a third electric lifting stage 13 corresponding to the translation stage. By controlling the first electric translation stage 14, the second electric translation stage 15, and the third electric translation stage 16, the azimuth angle and horizontal position of the collimator 3 can be adjusted; by controlling the first electric lifting stage 11, the second electric lifting stage 12, and the third electric lifting stage 13, the pitch angle and height of the collimator 3 can be adjusted.

[0057] The camera bracket 2 is used to mount the multi-channel imaging camera 1 under test, placing it at the light-emitting end of the collimator 3. Figure 6 The diagram shows the field-of-view distribution of each channel detector of the multi-channel imaging camera 1 under test, including the field of view 20 of the first channel detector, the field of view 21 of the second channel detector, and so on up to the field of view 22 of the Nth channel detector. The first target image position 23, the second target image position 24, the third target image position 25, and the fourth target image position 26 correspond to the edge field-of-view positions of a single channel detector of the multi-channel imaging camera 1 under test in the row and column directions, respectively. In actual testing, the attitude of the collimator 3 is controlled by the attitude adjustment device 6 so that the target 4 is sequentially imaged onto the field-of-view positions corresponding to each channel detector of the multi-channel imaging camera 1 under test.

[0058] The angle measurement assembly includes a cubic mirror 7 and an angle measuring device 8. The cubic mirror 7 is installed at the light-incident end of the collimator 3. The angle measuring device 8 is an autocollimator, which is located on the side of the cubic mirror 7 away from the collimator 3. It is used to cooperate with the cubic mirror 7 to obtain the angle change information of the collimator 3 in real time.

[0059] The acquisition and processing module is connected to the angle measuring device 8 and the multi-channel imaging camera 1 under test, respectively. It is used to acquire the angle change information obtained by the angle measuring device 8 and the imaging information of the target 4 obtained by the multi-channel imaging camera 1 under test. It calculates and outputs the parameter information of the alignment accuracy of each channel of the multi-channel imaging camera 1 under test. The parameter information includes the field overlap and field rotation deviation between the detectors of each channel. Based on the parameter information, the precision assembly of the multi-channel imaging camera can be realized.

[0060] Figure 7 The image shown is a schematic diagram of the target image acquired during the test of the multi-channel imaging camera 1. When the multi-channel imaging camera 1 is an area array imaging camera, the acquired image data will be as follows: Figure 7 As shown in the image on the left (a), a complete target image can be obtained. Then, the center position of the target image acquired by each channel detector of the multi-channel imaging camera 1 under test is extracted, and combined with the angle reading of the angle measuring device 8, the channel alignment accuracy of the multi-channel imaging camera 1 under test can be calculated.

[0061] This embodiment also provides a method for testing the channel alignment accuracy of a multi-channel imaging camera, including the following steps:

[0062] Step 1: Assemble the multi-channel imaging camera channel alignment accuracy testing device, and adjust the multi-channel imaging camera 1 and collimator 3 under test through the camera bracket 2 and attitude adjustment device 6 respectively, so that the center of the entrance pupil of the multi-channel imaging camera 1 under test is at the same height and coaxial with the center of the light output end of the collimator 3.

[0063] Step 2: Define any one of the channel detectors in the multi-channel imaging camera 1 under test as its reference channel detector (the reference channel of most multi-channel imaging cameras has been predetermined), and the rest are the channel detectors under test; then start the light source 5, and adjust the pose of the collimator 3 through the attitude adjustment device 6 so that the target 4 is imaged at the center of the field of view of the reference channel detector after being collimated by the collimator 3. At this time, clear the reading of the angle measuring device 8 to zero.

[0064] Step 3: Based on the field-of-view position distribution of each channel detector in the multi-channel imaging camera 1 under test, the collimator 3 is moved from the center of the field of view of the reference channel detector. The pose of the collimator 3 is changed sequentially by the attitude adjustment device 6 so that the target 4 is imaged sequentially at the center of the field of view of each channel detector after being collimated by the collimator 3. At the same time, the angle change information of the collimator 3 is recorded sequentially by the angle measuring device 8.

[0065] Step 4: Based on the images output by each channel detector and the angle change information recorded by the angle measuring device 8, the acquisition and processing module calculates the field of view overlap and field of view rotation deviation between each channel detector under test and the reference channel detector, thereby completing the test of the channel alignment accuracy of the multi-channel imaging camera.

[0066] In an area array imaging camera, the number of pixels of each channel detector is denoted as... Where i is the channel number, taking values ​​from 1, 2, ..., N; U represents the row direction, and V represents the column direction. The subsequent planning is as follows: Figure 6 The target image positions 23, 24, 25, and 26 within the field of view 20 of the first channel detector are shown. Each target image position is located near the 0.9 field of view of its respective channel.

[0067] The positions 23 of the first target image and 24 of the second target image are represented as follows: ;

[0068] The third target image position 25 and the fourth target image position 26 are represented as follows: .

[0069] Figure 6The movement angles of the collimator 3 corresponding to the fields of view of the first target image position 23 and the second target image position 24 are as follows:

[0070]

[0071]

[0072] In the formula: That is and It represents the angle of deflection of the collimator 3 when it moves along the detector row direction of the i-th channel of the multi-channel imaging camera 1 to the field of view of the first target image position 23 and the second target image position 24. , These are the pixel size and focal length of the detector in the i-th channel of the multi-channel imaging camera 1 under test, respectively; That is and , which represents the angle of deflection of the collimator 3 when it moves along the direction of the detector column of the i-th channel of the multi-channel imaging camera 1 to the field of view of the first target image position 23 and the second target image position 24; Let be the field of view angle between the center of the i-th channel detector of the multi-channel imaging camera 1 under test and the center of the reference channel detector.

[0073] Figure 6 The movement angles of collimator 3 corresponding to the fields of view of the third target image position 25 and the fourth target image position 26 are as follows:

[0074]

[0075]

[0076] In the formula, That is and , which represents the angle of deflection of the collimator 3 when it moves along the detector row direction of the i-th channel of the multi-channel imaging camera 1 to the field of view of the third target image position 25 and the fourth target image position 26; That is and , which represents the angle of deflection of the collimator 3 when it moves along the direction of the detector column of the i-th channel of the multi-channel imaging camera 1 to the field of view of the third target image position 25 and the fourth target image position 26.

[0077] The attitude adjustment device 6 controls the angle of the collimator 3 via corresponding lifting and translation platforms. When the collimator 3 needs to rotate in the azimuth direction, the first electric translation platform 14 moves a certain distance in one direction, while the second electric translation platform 15 and the third electric translation platform 16 move the same distance in the opposite direction. When the collimator 3 needs to rotate in the pitch direction, the first electric lifting platform 11 moves a certain distance in one direction, while the second electric lifting platform 12 and the third electric lifting platform 13 move the same distance in the opposite direction. The aforementioned moving distances are calculated using the following formula:

[0078]

[0079] In the formula: The distance the translation stage / lifting stage moves when the collimator 3 rotates at an angle in the azimuth or pitch direction. The vertical distance between the corresponding support leg of the first electric lifting platform 11 and the line connecting the corresponding support legs of the second electric lifting platform 12 and the third electric lifting platform 13; The angle at which the position of the collimator 3 offsets from the center field of view of the reference channel detector.

[0080] After the detectors of each channel of the multi-channel imaging camera 1 under test acquire the target image, the acquisition and processing module receives the image and uses algorithms such as Sobel, Prewitt, and Roberts to extract the edge information in the image. Figure 7 The edge data along the long side of the thin and thick lines shown are fitted with a straight line, and the resulting equation is as follows:

[0081]

[0082] In the formula: These are the fitting parameters for the thin line; These are the fitting parameters for the thick line.

[0083] Take the middle straight line of the fitted curve from the two edges of each of the thin and thick lines:

[0084]

[0085] Then, take the intersection of the straight lines between the thin and thick lines as the actual position of the target image:

[0086]

[0087] Next, based on the obtained rotation angle of the collimator 3 and the actual position of the target image, the alignment accuracy of each channel can be calculated, including the field-of-view overlap between the detector of the test channel and the reference channel detector of the area array imaging camera in the Y direction. The calculation formula is as follows:

[0088]

[0089] In the formula, This indicates taking the minimum value. and These are the measured angle values ​​corresponding to the first target image position 23 and the second target image position 24 on the reference channel, respectively. and This represents the measured angle values ​​corresponding to the first target image position 23 and the second target image position 24 on the channel under test; and These represent the measured values ​​of the positions of the first target image position 23 and the second target image position 24 in the Y direction on the reference channel, respectively. and These represent the measured values ​​of the positions 23 and 24 of the first target image on the channel under test in the Y direction, respectively. , These are the pixel angular resolutions of the reference channel detector and the detector under test, respectively. This indicates the measured position of the target image collected by the reference channel detector when the reading of the angle measuring device 8 is zeroed.

[0090] The calculation method for the field-of-view overlap between the detector of the test channel and the reference channel detector in the X direction of the area array imaging camera is the same as above, except that the target position and its data in the corresponding direction are replaced.

[0091] In an area array imaging camera, the field-of-view rotation deviation between each channel detector and the reference channel detector. The calculation is performed in the Y direction, using the following formula:

[0092]

[0093] In the formula: and These represent the measured X-direction angles corresponding to the first target image position 23 and the second target image position 24 on the channel under test, respectively. and These represent the measured X-direction angles corresponding to the first target image position 23 and the second target image position 24 on the reference channel, respectively. and These represent the measured X-direction positions corresponding to the first target image position 23 and the second target image position 24 on the channel under test, respectively. and These represent the measured X-direction positions corresponding to the first target image position 23 and the second target image position 24 on the reference channel, respectively.

[0094] In this embodiment, based on the field of view distribution position of the multi-channel imaging camera, the corresponding elevator and translation stage are controlled to rotate the collimator 3 sequentially to the field of view positions corresponding to the edge and center pixel positions of each channel detector of the multi-channel imaging camera 1 under test. The angle readings of the high-precision angle measuring device and the pixel coordinates of the target image acquired by each channel detector are recorded, and the channel alignment accuracy of the multi-channel imaging camera 1 under test is calculated accordingly.

[0095] Example 2

[0096] This embodiment provides a device and method for testing the channel alignment accuracy of a multi-channel imaging camera. The applicable multi-channel imaging camera 1 to be tested is a linear array imaging camera or an imaging spectrometer. The steps of the testing device and method are the same as in Embodiment 1, but the calculation methods for field overlap and field rotation deviation are slightly different from those in Embodiment 1, as detailed below:

[0097] For linear array imaging cameras or imaging spectrometers, the number of pixels in the width direction of each channel is denoted as... ,in, For the channel number, the planning is as follows: Figure 6 The first target image position 23 and the second target image position 24 shown are both located near the 0.9 field of view of each channel, and the first target image position 23 and the second target image position 24 are represented as follows:

[0098]

[0099] The channels corresponding to the linear array imaging camera and the imaging spectrometer only have an imaging field of view in the swath width direction. The movement angles of the collimator 3 corresponding to the fields of view of the first target image position 23 and the second target image position 24 are as follows:

[0100]

[0101]

[0102] In the formula: That is and It represents the angle of deflection of the collimator 3 when it moves along the detector row direction of the i-th channel of the multi-channel imaging camera 1 to the field of view of the first target image position 23 and the second target image position 24. , These are the pixel size and focal length of the detector in the i-th channel of the multi-channel imaging camera 1 under test, respectively; That is and , which represents the angle of deflection of the collimator 3 when it moves along the direction of the detector column of the i-th channel of the multi-channel imaging camera 1 to the field of view of the first target image position 23 and the second target image position 24; Let be the field of view angle between the center of the i-th channel detector of the multi-channel imaging camera 1 under test and the center of the reference channel detector.

[0103] like Figure 7 As shown, when the multi-channel imaging camera 1 under test is a linear array imaging camera, the acquired image data is based on the relative positional relationship between the collimator 3 and the linear array imaging camera. Figure 7 (a) One-dimensional image data indicated by I, II, and III in the figure. For an imaging spectrometer, the resulting target image will be... Figure 7 Based on the right-hand images (b), (c), and (d), the spectral dimension is broadened. At this point, the corresponding target position can be extracted at the fixed wavelength position in the spectral dimension.

[0104] The calculation method for the field-of-view overlap between the linear array imaging camera and the imaging spectrometer is the same as in Example 1, except that the target positions in the corresponding directions are replaced. When calculating the field-of-view overlap between each test channel detector and the reference channel detector, polynomial interpolation, spline interpolation, and centroid method are used to extract the pixel positions of the thin and thick lines in the target image, denoted as... and When only one pixel location can be extracted from the target image, the corresponding... Figure 7 Position II in (a) controls the attitude adjustment device 6 to move the image of target 4 to... Figure 7 (a) Only at position I or III can the thick and thin lines be distinguished. Then, combined with the readings from the angle measuring device 8, the relevant angle data is updated. The corresponding target position is calculated using the following formula. :

[0105]

[0106] In the formula, The slope of the thin line in the target image in the corresponding detector coordinate system is extracted from two target images acquired during the test. and And the difference in angular readings of the angle measuring device 8 in the direction perpendicular to the width of the image when acquiring the two target images. To perform the calculation, that is:

[0107]

[0108] In the formula: , representing the difference in the positional interval between the thick and thin lines obtained from two target images; and These represent the positions of the thick and thin lines in the first target image, respectively. and These represent the positions of the thick and thin lines in the second target image, respectively.

[0109] Field rotation deviation of linear imaging cameras and imaging spectrometers Calculate using the following formula:

[0110]

[0111] In the formula: , The difference in angle readings of the angle measuring device 8 in the direction perpendicular to the width of the image is measured when the target channel and the reference channel acquire two target images. and These represent the measured values ​​of the X-direction position intervals corresponding to the first target image position 23 and the second target image position 24 on the channel under test, respectively. and These represent the measured X-direction position intervals corresponding to the first target image position 23 and the second target image position 24 on the reference channel, respectively.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A device for testing the channel alignment accuracy of a multi-channel imaging camera, characterized in that: Includes a light source (5), a target (4), a collimator (3), a camera bracket (2), an angle measurement component, and a data acquisition and processing module; The light source (5) is installed at the light-inlet end of the collimator (3), and the optical axis of the light emitted from the light source (5) coincides with the central axis of the collimator (3); The target (4) is installed between the light source (5) and the collimator (3) and is located at the focal plane of the collimator (3); the target (4) is provided with a target pattern; The bottom of the collimator (3) is provided with an attitude adjustment device (6) for adjusting the attitude of the collimator (3). During the adjustment process, the light source (5) and the target (4) change synchronously with the attitude of the collimator (3). The camera bracket (2) is used to mount the multi-channel imaging camera (1) under test, so that it is located at the light-emitting end of the collimator (3); The angle measuring component includes a cubic mirror (7) and an angle measuring device (8); the cubic mirror (7) is installed at the light-incident end of the collimator (3); the angle measuring device (8) is located on the side of the cubic mirror (7) away from the collimator (3), and is used to cooperate with the cubic mirror (7) to obtain the angle change information of the collimator (3); The acquisition and processing module is connected to the angle measuring device (8) and the multi-channel imaging camera (1) under test respectively. It is used to acquire the angle change information obtained by the angle measuring device (8) and the target pattern information obtained by the multi-channel imaging camera (1) under test, and calculate and output the parameter information of the channel alignment accuracy of the multi-channel imaging camera (1) under test.

2. The multi-channel imaging camera channel alignment accuracy testing device according to claim 1, characterized in that: The attitude adjustment device (6) includes three sets of adjustment components, which are arranged in an isosceles triangle at the bottom of the collimator (3). The two sets of adjustment components located at the base angle of the isosceles triangle are respectively set at the bottom of the end of the collimator (3) closer to the target (4), and the set of adjustment components located at the apex angle of the isosceles triangle is set at the bottom of the other end of the collimator (3) away from the target (4). Each set of adjustment components includes a translation stage and a lifting stage. The translation stage is used to be installed on the test workbench and can move horizontally relative to the test workbench. The bottom of the lifting stage is connected to the translation stage, and the top is connected to the bottom of the collimator (3).

3. The multi-channel imaging camera channel alignment accuracy testing device according to claim 1, characterized in that: In each set of adjustment components, the bottom of the lifting platform is spherically hinged to the translation platform, and the top is spherically hinged to the bottom of the parallel light tube (3).

4. The multi-channel imaging camera channel alignment accuracy testing device according to claim 1, characterized in that: The angle measuring device (8) is an autocollimator; The target pattern is a crosshair pattern composed of thick lines (9) and thin lines (10).

5. A method for testing the channel alignment accuracy of a multi-channel imaging camera, characterized in that, Includes the following steps: Step 1: Assemble the multi-channel imaging camera channel alignment accuracy testing device according to any one of claims 1 to 4, and adjust the multi-channel imaging camera (1) under test and the collimator (3) respectively through the camera bracket (2) and the attitude adjustment device (6) so that the center of the entrance pupil of the multi-channel imaging camera (1) under test is at the same height and coaxial with the center of the light output end of the collimator (3); Step 2: Define any one of the channel detectors in the multi-channel imaging camera (1) under test as its reference channel detector, and the rest as the channel detectors under test; then start the light source (5), and adjust the pose of the collimator (3) through the attitude adjustment device (6) so that the target (4) is collimated by the collimator (3) and imaged at the center of the field of view of the reference channel detector. At this time, clear the reading of the angle measuring device (8). Step 3: Based on the field-of-view position distribution of each channel detector in the multi-channel imaging camera (1) under test, the pose of the collimator (3) is changed sequentially by the attitude adjustment device (6) so that the target (4) is imaged sequentially at the center of the field of view of each channel detector after being collimated by the collimator (3); at the same time, the angle change information of the collimator (3) is recorded sequentially by the angle measuring device (8). Step 4: Based on the images output by each channel detector and the angle change information recorded by the angle measuring device (8), the acquisition and processing module calculates the field overlap and field rotation deviation of each channel detector under test and the reference channel detector, thereby completing the test of the channel alignment accuracy of the multi-channel imaging camera.

6. The method for testing the channel alignment accuracy of a multi-channel imaging camera according to claim 5, characterized in that, In step 4, the field-of-view overlap between each test channel detector and the reference channel detector is calculated using any of the following methods: A1. If the multi-channel imaging camera (1) to be tested is an area array imaging camera, extract the edge data of the corresponding target pattern from the image output by each channel detector, and obtain the position information of the corresponding target pattern after straight line fitting; then, combine the corresponding angle change information to calculate the field of view overlap between each channel detector to be tested and the reference channel detector in the X and Y directions respectively. A2. If the multi-channel imaging camera (1) to be tested is a linear array imaging camera or an imaging spectrometer, extract the position information of the corresponding target pattern from the image output by each channel detector, and then combine the corresponding angle change information to calculate the field of view overlap between each channel detector to be tested and the reference channel detector.

7. The method for testing the channel alignment accuracy of a multi-channel imaging camera according to claim 5, characterized in that, In step 4, the field-of-view rotation deviation between each detector of the channel under test and the reference channel detector is calculated using any of the following methods: B1. If the multi-channel imaging camera to be tested (1) is an area array imaging camera, calculate the field rotation deviation of each channel detector to be tested and the reference channel detector in the Y direction. B2. If the multi-channel imaging camera (1) to be tested is a linear array imaging camera or an imaging spectrometer, calculate the field of view rotation deviation between the detector of each channel to be tested and the reference channel detector in the width direction.

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