Optical testing method and system for inter-chip precision of linear array camera detector

Abstract

The invention provides a line-scan digital camera detector inter-sheet precision optical test method, which comprises the following steps: acquiring image data on two adjacent detectors, an image corresponding to the image data being an image formed by a target on the adjacent detectors of a to-be-tested line-scan digital camera; according to the image data, inter-sheet rotation deviation, inter-sheet along-track deviation and inter-sheet vertical-track deviation of two adjacent detectors are calculated; and repeating the steps until the image data of the target on all adjacent detectors are obtained, and calculating the inter-sheet rotation deviation, inter-sheet along-track deviation and inter-sheet vertical-track deviation of all two adjacent detectors. According to the invention, the technical problem that the splicing precision and stability between the line-scan digital camera detector sheets cannot be conveniently tested at a complete machine level is solved.

Description

Technical Field

[0001] This invention relates to the field of aerial photogrammetry and remote sensing, and more specifically, to a method and system for optical testing of inter-chip precision of linear array camera detectors. Background Technology

[0002] Linear scan cameras are widely used in aerospace optical imaging due to their wide swath and high signal-to-noise ratio. To achieve the wide swath, the focal plane of a linear scan camera is composed of multiple detectors stitched together. Common stitching methods include collinear stitching (also called optical stitching), staggered stitching, and direct mechanical stitching. The accuracy of detector stitching is of particular concern in the direction perpendicular to the optical axis, including inter-piece rotational deviation (angular measurement), inter-piece along-track deviation (translation), and inter-piece perpendicular to-track deviation (translation). Their values ​​and stability directly determine the interior orientation elements of the linear array camera, and thus affect the overall satellite geometric positioning accuracy.

[0003] For a long time, due to the lack of suitable whole-system-level testing methods, the stitching accuracy of line-scan camera detectors has been largely defined as a Class II unmeasurable item, meaning it is unmeasurable at the whole-system level but measurable at the component level. Component-level testing can only be performed during detector stitching (before focal plane integration) using methods such as coordinate measuring machines. Although complete interior orientation element calibration of the line-scan camera can be used for whole-system-level testing of inter-chip stitching accuracy, it is too time-consuming (times on end) and has extremely high environmental requirements (requiring a highly stable environment such as an air-bearing platform), making it unsuitable for routine testing. Furthermore, because data from each detector is acquired in a time-sharing manner, it is impossible to perform inter-chip accuracy stability testing. This leads to the following uncertainties: whether the stitching accuracy of the line-scan camera detector is consistent before and after focal plane integration, whether it changes before and after mechanical testing, and whether it is stable during imaging. These hidden problems cannot be exposed in advance, increasing on-orbit and in-flight risks. Therefore, it is urgent to study a convenient whole-system-level testing method for the stitching accuracy and stability of line-scan camera detectors.

[0004] To achieve inter-chip accuracy testing of camera detectors, related technologies have been proposed: Patent CN117011392A discloses an improved precision angle measurement method for calibrating the interior orientation elements of an area array camera. This method involves arranging the measuring equipment according to the precision angle measurement method, imaging each measuring line with the camera, constructing a distortion model, and using a nonlinear optimization algorithm to solve for the interior orientation elements. This method reduces the requirement for the parallelism accuracy between the parallel light and the camera image coordinate axes, but it is only applicable to area array cameras.

[0005] Patent CN104655153A discloses a method for calibrating the interior orientation elements of a mapping camera based on matrix orthogonality. This method uses a camera to image a star chart collimated by a collimator, changes the shooting angle using a turntable to acquire multi-angle images of the star chart, and then uses the orthogonality of the rotation matrix to solve for the camera's interior orientation elements. This method eliminates the influence of turntable accuracy on the calibration results, but it is only applicable to area scan cameras.

[0006] Patent CN116962665A discloses a general method for testing camera in-camera orientation elements and geometric distortion. This method involves building a test system, leveling the camera under test and the collimator, and repeatedly adjusting the relative orientation of the light source and camera for multiple shots. The principal point, principal distance, and distortion are then calculated using the least squares method. However, this method is a form of camera in-camera orientation element calibration, which is time-consuming and has extremely high environmental requirements, making it unsuitable for routine testing of inter-chip accuracy in line-scan camera detectors.

[0007] Patent CN110779688A discloses a method for testing the field-of-view stitching accuracy of large-view area array devices. This method involves first performing inner field-of-view stitching on the focal plane components corresponding to N lenses (N≥2), then performing outer field-of-view stitching and measuring the stitching error between the focal plane components of the lenses, thereby achieving field-of-view stitching for all area array devices. This method is highly operable and has significant practical value, but it is only applicable to area array cameras.

[0008] Patent CN110738613A discloses a method, apparatus, device, and medium for real-time correction of image stitching in a linear array detector. It acquires real-time imaging data from the linear array detector, performs pre-correction processing, and applies gradient interpolation correction to the DN values ​​of the pixel set to be corrected, thus avoiding the influence of manufacturing processes and other factors on the stitching of the linear array images. However, this method pertains to image-level correction of linear array detector stitching and does not involve inter-chip accuracy testing.

[0009] The aforementioned existing patents and literature have failed to effectively solve the problem of convenient whole-machine-level testing of the splicing accuracy and stability between detector chips in linear array cameras with multiple detector chips spliced ​​together on the focal plane. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for testing the inter-chip precision optical accuracy of a linear array camera detector.

[0011] According to one aspect of the present invention, the present invention provides an optical testing method for inter-chip precision of a linear array camera detector, comprising: Step 1: Acquire image data from two adjacent detectors, wherein the image data corresponds to the image formed by the target on the adjacent detectors of the linear array camera under test; Step 2: Based on the image data, calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of two adjacent detectors; Step 3: Repeat Step 1 and Step 2 until image data of the target on all adjacent detectors are obtained, and calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of all adjacent detectors.

[0012] Preferably, the target includes a substrate with two sets of master patterns. The two sets of master patterns are imaged on two adjacent detectors, and each set of master patterns includes one or two sub-patterns, which include vertical stripes and oblique stripes.

[0013] Preferably, when the sub-pattern is imaged on the detector, the vertical stripes are perpendicular to the detector's line column direction.

[0014] Preferably, the target is imaged on the detector after being calibrated with parallel light.

[0015] Preferably, in step two, the formula used to calculate the inter-piece rotational deviation is as follows:

[0016] in,

[0017] In the formula, Δγ represents the inter-slice rotational deviation between two adjacent detector slices covered by the target in the linear array camera under test, A and B represent a set of parent patterns, i represents a general sub-pattern, a1 and a2 specifically refer to sub-patterns of parent pattern A, b1 and b2 specifically refer to sub-patterns of parent pattern B, and γ a γ b These represent the tilt angles of the linear array detectors under test covered by parent pattern A and parent pattern B, respectively. , These represent the centroid pixel numbers of the vertical and oblique stripes of subpattern i on the detector, respectively. k represents the coordinates along the track of the intersection point of the vertical and diagonal stripes of subpattern i on the target. i The slope of the slanted stripe of subpattern i is represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscript i = a1, a2, b1, b2; λ represents the scaling factor from the target to the image plane of the linear array camera under test. When only the inter-plate along-rail deviation and inter-plate perpendicular deviation are measured, γ a =0, γ b =0.

[0018] Preferably, in step two, the formula used to calculate the inter-segment deviation along the track is as follows:

[0019] In the formula, Δy represents the inter-segment track deviation between two adjacent detectors of the linear array camera under test, in pixels. design This represents the design value of the inter-segment spacing along the track between two adjacent detectors of the linear array camera under test. A and B represent a set of parent patterns, i represents a general sub-pattern, a1 and a2 specifically refer to sub-patterns of parent pattern A, b1 and b2 specifically refer to sub-patterns of parent pattern B, and γ a γ b These represent the tilt angles of the linear array detectors under test covered by parent pattern A and parent pattern B, respectively. , These represent the first and last pixel numbers of the linear array detector under test corresponding to the parent pattern A, respectively. , These represent the first and last pixel numbers of the linear array detector under test corresponding to the parent pattern B, respectively. , These represent the centroid pixel numbers of the vertical and oblique stripes of subpattern i on the detector, respectively. k represents the coordinates along the track of the intersection point of the vertical and diagonal stripes of subpattern i on the target. i The slope of the slanted stripe of subpattern i is represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscript i = a1, b1; λ represents the scaling factor from the target to the image plane of the linear array camera under test. When the detectors of the linear array camera under test are collinearly stitched, Δy design = 0; When the detectors of the linear array camera under test are not collinearly stitched, Δy design ≠ 0.

[0020] Preferably, in step two, the formula used to calculate the vertical deviation between the sections is as follows:

[0021] In the formula, Δx represents the vertical deviation between two adjacent detectors of the linear array camera under test, in pixels; A and B represent a set of parent patterns; i represents a general sub-pattern; a1 and a2 specifically refer to sub-patterns of parent pattern A; b1 and b2 specifically refer to sub-patterns of parent pattern B; n design This represents the design value of overlapping pixels between two adjacent detectors of the linear array camera under test; This indicates the tail pixel number of the linear array detector under test corresponding to the parent pattern A. This indicates the first pixel number of the linear array detector under test corresponding to the parent pattern B. The centroid pixel number on the detector represents the image of the vertical stripes of subpattern i. The vertical coordinates of the intersection of the vertical and inclined stripes of subpattern i on the target are represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscripts i = a1, b1 are represented by λ, which represents the scaling factor from the target to the image plane of the linear array camera under test.

[0022] The scaling factor λ from the target to the image plane of the linear array camera is calculated as follows: When the parent pattern A or parent pattern B contains N ≥ 2 vertical stripes, the expression for the scaling factor λ is:

[0023] In the formula, This represents the vertical track coordinate spacing between two vertical stripes on parent pattern A or parent pattern B. This represents the centroid pixel spacing of the image of the two vertical stripes on the parent pattern A or parent pattern B on the detector.

[0024] When both parent pattern A and parent pattern B contain 1 vertical stripe N, the scaling factor λ is expressed as follows:

[0025] In the formula, f1 represents the focal length of the collimator, f0 represents the focal length of the camera under test, and δ0 represents the pixel size of the detector of the camera under test.

[0026] According to another aspect of the present invention, an optical testing system for inter-chip precision of a linear array camera detector is provided, characterized in that it comprises: Module 1: Acquire image data from two adjacent detectors, wherein the image is the image of the target on the adjacent detectors of the linear array camera under test; Module 2: Based on image data, calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of two adjacent detectors; Module 3: Repeatedly trigger the operation of Module 1 and Module 2 until image data of the target on all adjacent detectors is acquired, and calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of all adjacent detectors.

[0027] Preferably, the target includes a substrate with two sets of master patterns. The two sets of master patterns are imaged on two adjacent detectors, and each set of master patterns includes one or two sub-patterns, which include vertical stripes and oblique stripes.

[0028] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention enables the inter-chip accuracy testing of adjacent detectors by imaging a specific patterned optical test target with the camera under test, thus solving the problem of inconvenient testing of the inter-chip accuracy of detectors at the whole-machine level in multi-detector stitched focal plane linear array cameras.

[0029] 2. This invention simultaneously images an optical test target with a specific pattern using adjacent detectors. The relative position between adjacent detector chips can be obtained in a single measurement. The results of multiple or long-term measurements can be used for stability testing between detector chips in a line scan camera.

[0030] 3. This invention achieves relative measurement by simultaneously imaging a specific patterned optical test target with adjacent detectors, reducing the requirements for the stability of the test environment. The system has a simple structure and can be widely used for inter-chip accuracy and stability testing of linear array camera detectors. Attached Figure Description

[0031] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 Figure I shows a typical configuration of an optical test target for inter-chip precision testing of a linear array camera detector. Figure 2 Diagram of the optical testing system for inter-chip precision of a linear array camera detector; Figure 3 A flowchart illustrating the optical testing method for inter-chip precision of linear array camera detectors; Figure 4 Schematic diagram of the working principle of the optical testing method for inter-chip precision of linear array camera detectors; Figure 5 Examples of optical target configuration diagrams for inter-chip precision testing of linear array camera detectors: II~V; Figure 6 A simplified configuration diagram of the optical test target for inter-chip precision testing of a linear array camera detector. Figure 7 Physical design drawing of the optical test target for inter-chip precision testing of a linear array camera detector; Figure 8 This is an image of two adjacent detectors covered by the target in a linear array camera.

[0032] In the figure, 1. Target, 2. Target substrate, 3. Pattern A, 4. Pattern B, 5. Sub-pattern a1, 6. Sub-pattern a2, 7. Sub-pattern b1, 8. Sub-pattern b2, 9. Vertical stripe, 10. Tilt stripe, 11. Collimator, 12. Linear array camera, 13. First detector, 14. Second detector. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0034] For ease of understanding, the terms or concepts involved in the methods provided in this application are explained below: (1) Linear scan camera A line scan camera is an imaging device that contains only one row of pixels (arranged in a line), relying on the movement of the target or the camera itself to complete the scanning and imaging of the entire image. It is widely used in high-precision remote sensing, industrial inspection and other fields, and is characterized by high imaging resolution and expandable imaging width.

[0035] (2) Detector The imaging sensor in a line-scan camera, typically a CCD or CMOS image sensor, is responsible for acquiring light signals and converting them into digital image signals. Each detector contains multiple linearly arranged pixels. In this invention, multiple detectors are stitched together in a collinear / interlaced / mechanical manner to expand the imaging swath.

[0036] (3) Pixel A pixel is the smallest sampling unit in an image. In a detector, a pixel corresponds to a small area of ​​the photosensitive region, has a fixed physical size (e.g., 7 μm), and its number can be used to indicate its spatial location in the image.

[0037] (4) Detector linear array direction This refers to the direction in which pixels in the detector are physically arranged continuously, and it is also the direction of the "line" in the image, defining the arrangement order of the imaging data. In this invention, the target pattern needs to be arranged approximately perpendicular to this direction to achieve accurate positioning of the stripes and deviation calculation.

[0038] (5) Along the track direction The direction of imaging scanning or flight motion (the Y-axis direction in this invention) corresponds to the time axis direction of detector imaging. In this invention, it is used to evaluate the forward and backward translational deviation (Δy) between detectors.

[0039] (6) Vertical direction The direction perpendicular to the track direction (X-axis direction in this invention), also known as the "cross-track" or "scanning direction," is consistent with the direction of the pixel line array. In this invention, it is used to evaluate the lateral offset (Δx) between detectors.

[0040] (7) Inter-slice rotational deviation This refers to the angular misalignment that occurs between two adjacent detectors during the stitching process, measured in degrees (or radians). Rotational deviation will cause image stripes to tilt, affecting geometric consistency. This invention calculates this deviation using the stripe position difference.

[0041] (8) Inter-piece track deviation This refers to the translational misalignment of adjacent detectors along the track direction, measured in pixels. In this invention, it is calculated based on the difference between the centroid position of the stripes in the image and the design value.

[0042] (9) Deviation between plates and vertical rails This refers to the translational offset of adjacent detectors along the vertical track, measured in pixels. It is used to determine whether there is lateral misalignment during detector splicing.

[0043] (10) Stability of splicing accuracy This refers to the ability of detectors to maintain stable stitching deviations over time. It is calculated by comparing deviation values ​​across different time periods, with the maximum change divided by the time length, expressed in pixels per minute or pixels per 10 minutes. (11) Vertical stripes These are fringes perpendicular to the detector's linear array, used to measure the image's deviation in the vertical direction. The centroid position of the fringes is the basis for deviation calculation.

[0044] (12) Slanted stripes These are patterned fringes that are tilted at a certain angle relative to the vertical fringes, used to calculate the rotational angular deviation between detectors. Their positional difference in the image reflects the angular offset.

[0045] (13) Centroid Pixel Number This refers to the pixel number corresponding to the centroid (geometric center) of a stripe pattern in an image. By extracting the centroid pixel position, the actual deviation of the corresponding pattern can be calculated.

[0046] (14) Scaling factor (λ) This represents the scaling factor (pixels / mm) from the target pattern to the imaging surface of the line scan camera, used to convert the geometric dimensions on the target into pixel dimensions in the image. This parameter plays a conversion role in the deviation calculation formula.

[0047] (15) A collimator is an optical device used to convert a point light source or pattern into a parallel beam of light with a consistent direction. In this invention, it is used to simulate the imaging condition of a target at "infinity" to ensure the accuracy of deviation testing.

[0048] This application can be applied to the overall testing of line scan cameras. The focal plane of a line scan camera is composed of multiple detectors stitched together. However, existing overall testing methods are demanding and time-consuming, making them unsuitable for routine testing. Therefore, this application provides an optical testing method for the inter-detector precision of line scan cameras, such as... Figure 3 As shown in the figure, this is a flowchart illustrating the method. The method will be explained in detail below.

[0049] Figure 4The working principle of this method is illustrated. Mother pattern A3 and mother pattern B4 are imaged on two adjacent detectors of the line array camera under test, respectively. Using the centroid pixel number of the images of the vertical and oblique stripes of sub-patterns a15, a26, b17, and b28 on the target, combined with the design parameters of the optical test target for inter-segment accuracy of the detectors of the line array camera 12, the inter-segment rotational deviation, inter-segment along-track deviation, and inter-segment vertical deviation of the two adjacent detectors covered by the target in the line array camera 12 under test can be obtained.

[0050] The method includes: Step 1: Acquire image data from two adjacent detectors. The image data corresponds to the image of the target 1 on the adjacent detectors of the linear array camera 12 under test. For easy differentiation, the adjacent detectors are designated as the first detector 13 and the second detector 14.

[0051] It is understandable that the target 1 is imaged on the detector after passing through the collimator 11. The collimator 11 transforms the light rays of the target pattern into parallel light, simulating a target from infinity, thus eliminating projection errors caused by the object distance and ensuring the reliability of the stitching accuracy measurement. The specific positional relationship between the line scan camera 12, the collimator 11, and the target 1 is as follows: Figure 2 As shown.

[0052] For example, target 1 includes substrate 2, on which two sets of master patterns are provided. The two sets of master patterns are imaged on two adjacent detectors. Each set of master patterns includes one or two sub-patterns. The sub-patterns include vertical stripes 9 and oblique stripes 10. For easy distinction, the two sets of master patterns are designated as master pattern A3 and master pattern B4. Master pattern A3 includes sub-patterns a15 and a26, and master pattern B4 includes sub-patterns b17 and b28. Each sub-pattern includes vertical stripes and oblique stripes. During imaging, the vertical stripes are ensured to be perpendicular to the line array direction of the linear array camera detector. At the same time, each master pattern is ensured to cover one detector. That is, master pattern A3 is imaged on the first detector and master pattern B4 is imaged on the second detector, or master pattern A3 is imaged on the second detector and master pattern B4 is imaged on the first detector.

[0053] In addition, during testing, it is sometimes not necessary to detect the rotational deviation between wafers. When it is not necessary to detect the rotational deviation between wafers, the master pattern only needs to have one sub-pattern.

[0054] It is understood that this application does not impose restrictions on the shape and position of the parent pattern and sub-patterns. The positional relationship between the sub-patterns can be adjusted according to the splicing relationship of the linear array camera detector under test, as long as a set of sub-patterns can cover a corresponding detector area. The shapes of the sub-patterns can be completely identical, completely different, or partially identical. Each sub-pattern can contain one or more vertical or oblique stripes, as shown in the specific example. Figure 1 , Figure 5 As shown, Figure 1 Example I of a typical target configuration is shown. Figure 5 Examples of target designs, II to V, are shown.

[0055] Step 2: Based on the image data, calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of two adjacent detectors.

[0056] Understandably, the formula used to calculate the inter-slice rotational deviation is as follows:

[0057] in,

[0058] In the formula, Δγ represents the inter-segment rotational deviation between two adjacent detectors covered by the target in the linear array camera under test, and γ a γ b These represent the tilt angles of the linear array detectors under test covered by parent pattern A and parent pattern B, respectively. , These represent the centroid pixel numbers of the vertical and oblique stripes of subpattern i on the detector, respectively. k represents the coordinates along the track of the intersection point of the vertical and diagonal stripes of subpattern i on the target. i The slope of the slanted stripe of subpattern i is represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscripts i = a1, a2, b1, b2; λ represents the scaling factor from the target to the image plane of the linear array camera under test. When only the inter-plate along-rail deviation and inter-plate perpendicular deviation are measured, γ a =0, γ b =0.

[0059] Preferably, in step two, the formula used to calculate the inter-segment deviation along the track is as follows:

[0060] In the formula, Δy represents the inter-segment track deviation between two adjacent detectors of the linear array camera under test, in pixels. design γ represents the design value of the inter-chip track spacing between two adjacent detectors of the linear array camera under test. aγ b These represent the tilt angles of the linear array detectors under test covered by parent pattern A and parent pattern B, respectively. , These represent the first and last pixel numbers of the linear array detector under test corresponding to the parent pattern A, respectively. , These represent the first and last pixel numbers of the linear array detector under test corresponding to the parent pattern B, respectively. , These represent the centroid pixel numbers of the vertical and oblique stripes of subpattern i on the detector, respectively. k represents the coordinates along the track of the intersection point of the vertical and diagonal stripes of subpattern i on the target. i The slope of the slanted stripe of subpattern i is represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscripts i = a1, b1; λ represents the scaling factor from the target to the image plane of the linear array camera under test. When the detectors of the linear array camera under test are collinearly stitched, Δy design = 0; When the detectors of the linear array camera under test are not collinearly stitched, Δy design ≠ 0.

[0061] Preferably, in step two, the formula used to calculate the vertical deviation between the sections is as follows:

[0062] In the formula, Δx represents the vertical deviation between two adjacent detectors of the linear array camera under test, in pixels, and n design This represents the design value of overlapping pixels between two adjacent detectors of the linear array camera under test; This indicates the tail pixel number of the linear array detector under test corresponding to the parent pattern A. This indicates the first pixel number of the linear array detector under test corresponding to the parent pattern B. The centroid pixel number on the detector represents the image of the vertical stripes of subpattern i. The vertical coordinates of the intersection of the vertical and inclined stripes of subpattern i on the target are represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscripts i = a1, b1 are also represented by λ, which represents the scaling factor from the target to the image plane of the linear array camera under test.

[0063] Preferably, the scaling factor λ from the target to the image plane of the linear array camera is calculated as follows: When the parent pattern A or parent pattern B contains N ≥ 2 vertical stripes, the expression for the scaling factor λ is:

[0064] In the formula, This represents the vertical track coordinate spacing between two vertical stripes on parent pattern A or parent pattern B. This represents the centroid pixel spacing of the image of the two vertical stripes on the parent pattern A or parent pattern B on the detector.

[0065] When both parent pattern A and parent pattern B contain 1 vertical stripe N, the scaling factor λ is expressed as follows:

[0066] In the formula, f1 represents the focal length of the collimator, f0 represents the focal length of the camera under test, and δ0 represents the pixel size of the detector of the camera under test.

[0067] Step 3: Repeat Step 1 and Step 2 until image data of the target on all adjacent detectors are obtained, and calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of all adjacent detectors.

[0068] The following example uses a line scan camera to demonstrate the detection method described above.

[0069] The focal plane of the linear array camera 12 is composed of three 6k detectors spliced ​​together in a collinear manner, with a pixel size of 7μm. The design value of overlapping pixels between adjacent detectors is 100 pixels. It is necessary to test the inter-detector track deviation (translation amount) and inter-detector vertical track deviation (translation amount).

[0070] The optical test target for inter-chip precision of the linear array camera detector is as follows: Figure 6 The diagram shows a simplified configuration. Because the inter-chip rotational deviation of adjacent detectors is not measured, the parent pattern A3 only contains sub-pattern a15, and the parent pattern B4 only contains sub-pattern b17.

[0071] The physical design drawing of the optical test target for inter-chip precision of the linear array camera detector is shown below. Figure 7 As shown, sub-pattern a15 and sub-pattern b17 have the same shape, are horizontally aligned, and have the same slope of k for the diagonal stripes. a1 = k b1 = -2.15; the coordinates along the track of the intersection point of the vertical stripe (the first one from the left) and the diagonal stripe of the sub-pattern a15 on the target. Vertical coordinates The coordinates along the track of the intersection point of the vertical and diagonal stripes of subpattern b17 on the target. Vertical coordinates ,satisfy:

[0072] The images of the two adjacent detectors covered by the target in the linear array camera are as follows: Figure 8 (a) Figure 8 As shown in (b).

[0073] The first and last pixel numbers of the first detector of the linear array under test corresponding to the master pattern A3 are respectively =1, =6144, the centroid pixel numbers of the vertical stripe (selecting the first one from the left) and the oblique stripe of sub-pattern a1 on the detector are respectively... =5879.93, =5961.96; The first and last pixel numbers of the second detector of the linear array under test corresponding to the master pattern B4 are respectively =1, =6144, the centroid pixel numbers of the vertical stripe (selecting the first one from the left) and the oblique stripe (10) of subpattern b1 on the detector are respectively =118.98, =197.14.

[0074] The scaling factor from target 1 to the image plane of the linear array camera under test is λ = 11.79 pixels / mm.

[0075] Since the inter-chip rotational deviation between adjacent detectors is not measured, the tilt angle γ is taken. a =0, γ b =0.

[0076] Thus, the inter-segment along-track deviation Δy = 8.32 pixels and the inter-segment perpendicular deviation Δx = -4.77 pixels are obtained between two adjacent detectors of the linear array camera 12 under test.

[0077] In addition, this method can also be used for stability testing. Taking the above-mentioned line array camera 12 as an example, the focal plane of a certain line array camera 12 is composed of three 6k detectors spliced ​​together in a collinear manner, with a pixel size of 7μm. The design value of overlapping pixels between adjacent detectors is 100 pixels. Stability tests of the inter-detector track deviation (translation amount) and inter-detector vertical track deviation (translation amount) need to be performed.

[0078] The following uses the present invention to test the inter-chip stability of the linear array camera detector.

[0079] Except for the imaging time of the line array camera 12 under test being set to 10 minutes, the other settings and operations are the same as in Example 3.

[0080] Image data from adjacent detectors were collected for the first 1 second, middle 1 second, and last 1 second of a 10-minute timeframe. The inter-segment along-track deviation Δy and inter-segment vertical deviation Δx of the two adjacent detectors of the linear array camera under test were calculated and are shown in Table 1.

[0081] The test results are shown in Table 1. This table indicates that the inter-segment stability of the linear array camera detector is 0.14 pixels / 10min along the track direction and 0.04 pixels / 10min perpendicular to the track direction. The inter-segment stability test results of two adjacent detectors of the linear array camera under test are shown in Table 1 below.

[0082] Table 1 Where stability = .

[0083] The present invention also provides an optical testing system for inter-chip precision of a line array camera detector. The optical testing system for inter-chip precision of a line array camera detector can be implemented by executing the process steps of the optical testing method for inter-chip precision of a line array camera detector. That is, those skilled in the art can understand the optical testing method for inter-chip precision of a line array camera detector as a preferred embodiment of the optical testing system for inter-chip precision of a line array camera detector.

[0084] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function as logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0085] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for optically testing the inter-chip precision of a linear array camera detector, characterized in that, include: Step 1: Acquire image data from two adjacent detectors, wherein the image data corresponds to the image formed by the target on the adjacent detectors of the linear array camera under test; Step 2: Based on the image data, calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of two adjacent detectors; Step 3: Repeat Step 1 and Step 2 until image data of the target on all adjacent detectors are obtained, and calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of all adjacent detectors.

2. The method according to claim 1, characterized in that, The target includes a substrate with two sets of master patterns. The two sets of master patterns are imaged on two adjacent detectors. Each set of master patterns includes one or two sub-patterns, and the sub-patterns include vertical stripes and diagonal stripes.

3. The method according to claim 2, characterized in that, When the sub-pattern is imaged on the detector, the vertical stripes are perpendicular to the direction of the detector's line array.

4. The method according to any one of claims 1-3, characterized in that, The target is imaged on the detector after being collimated by a collimator.

5. The method according to claim 1, characterized in that, In step two, the formula used to calculate the inter-piece rotational deviation is as follows: in, In the formula, Δγ represents the inter-slice rotational deviation between two adjacent detector slices covered by the target in the linear array camera under test, A and B represent a set of parent patterns, i represents a general sub-pattern, a1 and a2 specifically refer to sub-patterns of parent pattern A, b1 and b2 specifically refer to sub-patterns of parent pattern B, and γ a γ b These represent the tilt angles of the linear array detectors under test covered by parent pattern A and parent pattern B, respectively. , These represent the centroid pixel numbers of the vertical and oblique stripes of subpattern i on the detector, respectively. k represents the coordinates along the track of the intersection point of the vertical and diagonal stripes of subpattern i on the target. i The slope of the slanted stripe of subpattern i is represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscript i = a1, a2, b1, b2; λ represents the scaling factor from the target to the image plane of the linear array camera under test. When only the inter-slice along-track deviation and the inter-slice off-track deviation are measured, γ a = 0, γ b = 0.

6. The method according to claim 1, characterized in that, In step two, the formula used to calculate the inter-segment track deviation is as follows: In the formula, Δy represents the inter-segment track deviation between two adjacent detectors of the linear array camera under test, in pixels. design This represents the design value of the inter-segment spacing along the track between two adjacent detectors of the linear array camera under test. A and B represent a set of parent patterns, i represents a general sub-pattern, a1 and a2 specifically refer to sub-patterns of parent pattern A, b1 and b2 specifically refer to sub-patterns of parent pattern B, and γ a γ b These represent the tilt angles of the linear array detectors under test covered by parent pattern A and parent pattern B, respectively. , These represent the first and last pixel numbers of the linear array detector under test corresponding to the parent pattern A, respectively. , These represent the first and last pixel numbers of the linear array detector under test corresponding to the parent pattern B, respectively. , These represent the centroid pixel numbers of the vertical and oblique stripes of subpattern i on the detector, respectively. k represents the coordinates along the track of the intersection point of the vertical and diagonal stripes of subpattern i on the target. i The slope of the slanted stripe of subpattern i is represented by the superscript tgt, which represents the target and the superscript cam, which represents the detector. The subscript i = a1, b1; λ represents the scaling factor from the target to the image plane of the linear array camera under test. When the detectors of the linear array camera under test are collinearly stitched, Δy design = 0; When the detectors of the linear array camera under test are not collinearly stitched, Δy design ≠ 0.

7. The method according to claim 1, characterized in that, In step two, the formula used to calculate the vertical deviation between the sections is as follows: In the formula, Δx represents the vertical deviation between two adjacent detectors of the linear array camera under test, in pixels; A and B represent a set of parent patterns; i represents a general sub-pattern; a1 and a2 specifically refer to sub-patterns of parent pattern A; b1 and b2 specifically refer to sub-patterns of parent pattern B; n design This represents the design value of overlapping pixels between two adjacent detectors of the linear array camera under test; This indicates the tail pixel number of the linear array detector under test corresponding to the parent pattern A. This indicates the first pixel number of the linear array detector under test corresponding to the parent pattern B. The centroid pixel number on the detector represents the image of the vertical stripes of subpattern i. The vertical coordinates of the intersection of the vertical and inclined stripes of subpattern i on the target are represented by the superscript tgt, which represents the target, the superscript cam, which represents the detector, and the subscript i = a1, b1; λ represents the scaling factor from the target to the image plane of the linear array camera under test.

8. The method according to any one of claims 5-7, characterized in that, The scaling factor λ from the target to the image plane of the linear array camera is calculated as follows: When the parent pattern A or parent pattern B contains N ≥ 2 vertical stripes, the expression for the scaling factor λ is: In the formula, This represents the vertical track coordinate spacing between two vertical stripes on parent pattern A or parent pattern B. This represents the centroid pixel spacing of the image of the two vertical stripes on the parent pattern A or parent pattern B on the detector. When both parent pattern A and parent pattern B contain 1 vertical stripe N, the scaling factor λ is expressed as follows: In the formula, f1 represents the focal length of the collimator, f0 represents the focal length of the camera under test, and δ0 represents the pixel size of the detector of the camera under test.

9. A linear array camera detector inter-chip precision optical testing system, characterized in that, include: Module 1: Acquire image data from two adjacent detectors, wherein the image is the image of the target on the adjacent detectors of the linear array camera under test; Module 2: Based on image data, calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of two adjacent detectors; Module 3: Repeatedly trigger the operation of Module 1 and Module 2 until image data of the target on all adjacent detectors is acquired, and calculate the inter-segment rotational deviation, inter-segment along-rail deviation, and inter-segment vertical deviation of all adjacent detectors.

10. The system according to claim 9, characterized in that, The target includes a substrate with two sets of master patterns. The two sets of master patterns are imaged on two adjacent detectors. Each set of master patterns includes one or two sub-patterns, and the sub-patterns include vertical stripes and diagonal stripes.

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