Method and device for aligning focal plane of spliced detector based on collimator

Abstract

The invention relates to the technical field of infrared remote sensing, and particularly provides a collimator-based spliced detector focal plane alignment method and device, and the method comprises the steps: enabling a slit piece to sequentially pass through a collimator and an infrared camera lens, and then forming a slit piece local image on a focal plane of a first detector, adjusting the spacing distance between the splicing detector and the lens of the infrared camera until the imaging meets the requirement; enabling the slit piece to form slit piece local imaging on the focal plane of the next detector, adjusting the position of the slit piece until the local imaging of the slit piece meets the requirement, and recording the defocusing amount of the slit piece corresponding to the next detector; and correcting the positions of the corresponding detectors based on the defocusing amount of the slit sheet so as to correct all the detectors to a confocal plane position. Therefore, accurate alignment of the focal plane of the spliced detector can be realized, the operation is simple, and the use cost of the spliced detector can be reduced while wide imaging is realized.

Description

Technical Field

[0001] The invention relates to the field of infrared remote sensing technology, and in particular to a collimator-based focal plane alignment method for a spliced ​​detector and a collimator-based focal plane alignment device for a spliced ​​detector. Background Art

[0002] The satellite achieves imaging through push-scanning. The satellite's flight direction is the along-track direction, and the direction perpendicular to the flight direction is the through-track direction. The length of the ground strip in the through-track direction is the ground swath width, referred to as the swath width (i.e., the satellite scanning coverage width). The ground strip is imaged on the detector through the infrared camera payload. Through push-scanning in the along-track direction, two-dimensional ground area coverage is achieved.

[0003] The width is limited by the size of the detector's pixels. The larger the size, the larger the width. In order to expand the width, on the one hand, a single large-scale pixel array detector can be used, and on the other hand, a well-jointed detector array provided by the detector manufacturer can be used. Both methods can achieve a large width. However, these two methods are relatively expensive. Summary of the invention

[0004] In order to solve one of the above-mentioned technical problems, the present invention proposes the following technical solution.

[0005] The first aspect of the present invention proposes a method for aligning the focal plane of a spliced ​​detector based on a collimator, which is applied to an alignment system, wherein the alignment system includes a light source, a collimator, a slit, an infrared camera lens, and a spliced ​​detector including a plurality of detectors, wherein the light source is placed in front of the slit, the slit is placed vertically at the focal plane of the collimator, and the spliced ​​detector is mounted on the infrared camera lens. The method includes the following steps:

[0006] The slit sheet is made to form a local image of the slit sheet on the focal plane of the first detector after passing through the collimator and the infrared camera lens in sequence, and the spacing distance between the spliced ​​detector and the infrared camera lens is adjusted until the local image of the slit sheet meets the requirements;

[0007] Switch to the next detector, so that the slit sheet forms a local image of the slit sheet on the focal plane of the next detector after passing through the collimator and the infrared camera lens in sequence, adjust the position of the slit sheet until the local image of the slit sheet meets the requirements, record the defocus amount of the slit sheet corresponding to the next detector, and return to the second step until the defocus amount of the slit sheet corresponding to the last detector is obtained;

[0008] The position of the corresponding detector is corrected based on the defocus amount of the slit sheet to obtain a corrected spliced ​​detector, so as to achieve alignment of the focal plane of the detector.

[0009] In addition, the focal plane alignment method of the spliced ​​detector based on the collimator according to the above embodiment of the present invention may also have the following additional technical features.

[0010] According to one embodiment of the present invention, the method for aligning the focal plane of a spliced ​​detector based on a collimator further includes:

[0011] reinstalling the modified spliced ​​detector on the infrared camera lens;

[0012] Switching to the first detector so that the slit forms a local slit image on the focal plane of the first detector, and adjusting the spacing distance between the corrected spliced ​​detector and the infrared camera lens until the local slit image meets the requirements;

[0013] Switch to the next detector one by one so that the slit forms a local image of the slit on the focal plane of the next detector, and adjust the field of view angle of the infrared camera lens until the local image of the slit meets the requirements.

[0014] According to an embodiment of the present invention, when the light beam collimated by the slit plate passes through the collimator and is emitted in parallel to the infrared camera lens, the image formed in the infrared camera lens is perpendicular to the first detector.

[0015] According to an embodiment of the present invention, the local imaging of the slit sheet meets the requirement specifically including: the modulation transfer function of the detector corresponding to the local imaging of the slit sheet meets a preset indicator.

[0016] According to one embodiment of the present invention, the modulation transfer function of the detector is calculated by the following formula:

[0017]

[0018] Where MTF is the modulation transfer function of the detector, DN max is the pixel signal of the light-transmitting part of the slit, DN min is the pixel signal of the opaque part of the slit, and DN is the background noise of the detector.

[0019] According to one embodiment of the present invention, the alignment system also includes a five-dimensional adjustment frame, and the infrared camera lens is arranged on the five-dimensional adjustment frame. By adjusting the azimuth and pitch angle of the five-dimensional adjustment frame, switching to different detectors for slit imaging is performed; by adjusting the azimuth and pitch angle of the five-dimensional adjustment frame, the field of view angle of the infrared camera lens is adjusted.

[0020] According to an embodiment of the present invention, the alignment system further includes a translation stage, the slit is disposed on the translation stage, and the front-to-back distance of the slit is adjusted by adjusting the horizontal position of the translation stage, thereby adjusting the defocus amount of the slit.

[0021] According to one embodiment of the present invention, each of the detectors is located on a support seat respectively, and the position of the corresponding detector is corrected based on the defocus amount of the slit piece, including: calculating the defocus amount of the focal plane of the corresponding detector based on the defocus amount of the slit piece; grinding the support seat of the corresponding detector according to the defocus amount of the focal plane of the detector to realize the correction of the axial position of the detector, and reinstalling each detector on the corresponding support seat after the correction to obtain a corrected spliced ​​detector.

[0022] According to one embodiment of the present invention, the defocus amount of the corresponding detector focal plane is calculated based on the defocus amount of the slit piece, including: when the slit piece is imaged on each detector focal plane, the object distance of the slit piece, the image distance of the slit piece, and the object distance of the infrared camera lens and the image distance of the infrared camera lens are recorded; based on all the recorded results, the object distance relationship between the object distance of the slit piece and the object distance of the infrared camera lens and the image distance relationship between the image distance of the slit piece and the image distance of the infrared camera lens are calculated; according to the object distance relationship and the image distance relationship, the defocus amount relationship between the defocus amount of the slit piece and the defocus amount of the detector focal plane is calculated; according to the defocus amount relationship and the defocus amount of each slit piece, the defocus amount of the corresponding detector focal plane is obtained.

[0023] The second aspect of the present invention proposes a collimator-based spliced ​​detector focal plane alignment device, which is applied to an alignment system, wherein the alignment system includes a light source, a collimator, a slit, an infrared camera lens, and a spliced ​​detector including a plurality of detectors, wherein the light source is placed in front of the slit, the slit is placed vertically at the focal plane of the collimator, and the spliced ​​detector is mounted on the infrared camera lens. The device includes:

[0024] A first adjustment module is used to make the slit sheet form a local image of the slit sheet on the focal plane of the first detector after passing through the collimator and the infrared camera lens in sequence, and to adjust the spacing distance between the spliced ​​detector and the infrared camera lens until the local image of the slit sheet meets the requirements;

[0025] The second adjustment module is used to switch to the next detector, so that the slit sheet forms a local image of the slit sheet on the focal plane of the next detector after passing through the collimator and the infrared camera lens in sequence, adjust the position of the slit sheet until the local image of the slit sheet meets the requirements, record the defocus amount of the slit sheet corresponding to the next detector, and return to the second step until the defocus amount of the slit sheet corresponding to the last detector is obtained;

[0026] The correction module is used to correct the position of the corresponding detector based on the defocus amount of the slit sheet to obtain a corrected spliced ​​detector to achieve alignment of the focal plane of the detector.

[0027] The technical solution of the embodiment of the present invention adopts a light source, a slit, a collimator and an infrared camera lens to image the slit on the focal plane of the detector, and makes corresponding adjustments to correct the position of the detector. This can achieve precise alignment of the focal plane of the spliced ​​detector and is simple to operate. It can reduce the cost of using the spliced ​​detector while achieving wide-width imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of an alignment system according to an embodiment of the present invention.

[0029] Figure 2 The figure is a schematic diagram of the structure of a splicing detector according to an embodiment of the present invention.

[0030] Figure 3 The present invention is a flowchart of a method for aligning the focal plane of a spliced ​​detector based on a collimator according to an embodiment of the present invention.

[0031] Figure 4 This is a relationship curve between the defocus amount of the slit sheet and the defocus amount of the detector focal plane according to an example of the present invention.

[0032] Figure 5 It is a block diagram of a focal plane alignment device of a spliced ​​detector based on a collimator according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In order to reduce costs and achieve wide-width detection at the same time, the present invention proposes a focal plane alignment method of a spliced ​​detector based on a parallel light tube applied to an alignment system, which uses low-cost small-scale detectors for splicing and focal plane alignment to achieve a technical solution for wide-width imaging.

[0035] The alignment method is applied to the alignment system, Figure 1 Schematic diagram of the structure of an alignment system according to an embodiment of the present invention.

[0036] like Figure 1 As shown, the alignment system includes a light source 1, a slit plate 2, a collimator 3, an infrared camera lens 4 and a spliced ​​detector 5 including multiple detectors. The light source 1 is placed in front of the slit plate 2, the slit plate 2 is vertically placed at the focal plane of the collimator 3, and the spliced ​​detector 5 is mounted on the infrared camera lens 4.

[0037] The detector is a linear detector, and multiple detectors are mounted on a fixed base plate to obtain a combination, namely a spliced ​​detector 5. The fixed base plate has a support seat for mounting the detector, and each detector in the spliced ​​detector is located on a support seat. Figure 2 As shown, eight detectors (51-58) can be mounted on a fixed base plate 59 by fixing them on corresponding support seats to obtain a spliced ​​detector 5. That is, the spliced ​​detector 5 is a detector assembly that has only undergone preliminary assembly and installation of the detectors but has not been aligned.

[0038] The slit width of the slit sheet 2 is determined according to specific system indicators. The slit width D of the slit sheet 2 can be calculated according to system requirements, and the slit sheet 2 can be customized accordingly. The calculation formula is:

[0039]

[0040] Among them, D is the slit width of the slit plate, F is the focal length of the collimator, f is the focal length of the infrared camera lens, and d is the detector pixel size.

[0041] Figure 1 In the alignment system shown, when the slit sheet 2 is illuminated by a light source 9 such as a halogen lamp, the light beam passing through the slit sheet 2 is collimated by the collimator 3 and becomes a parallel light beam 6. After the parallel light beam 6 is emitted to the infrared camera lens 4 for imaging, a local image plane of the slit sheet is formed on the focal plane of each detector. The position of the infrared camera lens 4 is adjusted to switch to different detectors for slit sheet imaging, so that the slit sheet 2 is imaged on the focal plane of each detector.

[0042] In order to align the focal plane of the spliced ​​detector 5 using an alignment system, the present invention proposes a method for aligning the focal plane of the spliced ​​detector based on a collimator.

[0043] Figure 3 The present invention is a flowchart of a method for aligning the focal plane of a spliced ​​detector based on a collimator according to an embodiment of the present invention.

[0044] like Figure 3 As shown, the collimator-based spliced ​​detector focal plane alignment method includes the following steps S1 to S3 (alignment steps).

[0045] S1, the slit sheet is sequentially passed through the collimator and the infrared camera lens to form a local image of the slit sheet on the focal plane of the first detector, and the spacing distance between the spliced ​​detector and the infrared camera lens is adjusted until the local image of the slit sheet meets the requirements.

[0046] Furthermore, when the light beam collimated by the slit plate 2 passes through the collimator 3 and is emitted in parallel to the infrared camera lens 4 , the image formed in the infrared camera lens 4 is perpendicular to the first detector 51 .

[0047] Specifically, the light beam passing through the slit 2 is collimated by the collimation system of the collimator 3 and then emitted in parallel. After the parallel light beam 6 is imaged by the infrared camera lens 4, a local image of the slit is formed on the focal plane of the first detector 51. The image of the slit 2 through the infrared camera lens 4 is in a perpendicular relationship to the line array of the detector 51. The spacing distance between the spliced ​​detector 5 and the infrared camera lens 4 is adjusted. Specifically, the lens position is kept fixed, and the front and rear distance of the spliced ​​detector 5 is adjusted horizontally, so that the spliced ​​detector moves forward and backward until the local image of the slit on the focal plane of the first detector 51 meets the requirements, that is, the image is clear, and the imaging of the slit 2 can be recorded.

[0048] In this way, the alignment of the first detector 51 is achieved. In this case, the slit 2 is still at the focal plane of the collimator 3, that is, the defocus of the slit 2 is 0. By adjusting the front-to-back distance of the spliced ​​detector 5, the detector 51 is placed at the focal plane of the camera lens 4, that is, the defocus of the detector 51 is 0. The defocus of the slit refers to the distance between the slit and the focal plane of the collimator, and the defocus of the detector (focal plane) refers to the distance between the focal plane of the detector and the focal plane of the camera lens.

[0049] S2, switch to the next detector so that the slit sheet forms a local image of the slit sheet on the focal plane of the next detector after passing through the collimator and the infrared camera lens in sequence, adjust the position of the slit sheet until the local image of the slit sheet meets the requirements, record the defocus amount of the slit sheet corresponding to the next detector, and return to the second step until the defocus amount of the slit sheet corresponding to the last detector is obtained.

[0050] Specifically, after completing the imaging of the first detector 51, the position of the infrared camera lens 4 can be adjusted to switch to the next detector, the second detector 52, for imaging, so that the parallel light beam 6 collimated by the parallel light tube 3 of the slit 2 is imaged on the focal plane of the second detector 52 of the infrared camera. At this time, the detector 52 may not be in the best position for local slit imaging, so the position of the slit 2 is adjusted, specifically, the front and back distance of the slit 2 is adjusted (the slit moves back and forth in the horizontal direction), so that the local imaging of the slit in the focal plane of the second detector 52 meets the requirements, that is, the imaging is clear, and the imaging condition of the slit 2 can be recorded, and the defocus amount of the slit 2 at this time can also be recorded.

[0051] After completing the imaging of the second detector 52, the position of the infrared camera lens 4 can be adjusted to switch to the next detector, the third detector 53, for imaging, so that the parallel light beam 6 collimated by the parallel light tube 3 of the slit 2 is imaged on the focal plane of the third detector 53 of the infrared camera. At this time, the local slit imaging of the detector 53 may not be in the best position, so the position of the slit 2 is adjusted, specifically, the front and rear distance of the slit 2 is adjusted to move the slit forward and backward in the horizontal direction), so that the local imaging of the slit in the focal plane of the third detector 53 meets the requirements, that is, the imaging is clear, and the imaging condition of the slit 2 can be recorded, and the defocus amount of the slit 2 at this time can also be recorded.

[0052] After completing the imaging of the eight detectors in sequence according to the above steps, the defocus and imaging conditions of the slit corresponding to each detector can be obtained. The defocus of the slit corresponding to the first detector is 0, and the defocus of the second detector (compared to the infrared camera) is also 0. The defocus of the slits corresponding to the second to eighth detectors is not 0.

[0053] S3, correcting the position of the corresponding detector based on the defocus amount of the slit sheet to obtain a corrected spliced ​​detector to achieve alignment of the detector focal plane.

[0054] Specifically, according to step S2, the defocus amount of the slit 2 during each imaging is obtained, and the position of the corresponding detector relative to the fixed base plate, specifically the axial position, is corrected accordingly, that is, the position of the second to eighth detectors in the axial direction is corrected so that the focal planes of all detectors of the stitched detector 5 are in the same plane, that is, the confocal plane, and the corrected stitched detector can be obtained, thereby realizing the focal plane alignment of the stitched detector.

[0055] When correcting the position, first separate the splicing detector 5 from the infrared camera lens 4, separate the second to eighth detectors from the corresponding support bases, and then correct the positions one by one, and finally install the second to eighth detectors in the corresponding support bases with the same number or original sequence and original support bases. Before and after the correction, the support bases corresponding to each detector will not be converted.

[0056] By adopting the above scheme, the embodiment of the present invention does not need to use the spliced ​​detector provided by the manufacturer, but rather preliminarily combines multiple low-cost small-scale detectors on the user side to obtain a spliced ​​detector, and further performs focal plane alignment on the spliced ​​detector through the above steps S1 to S3, thereby achieving accurate arrangement of each detector, thereby ensuring the performance of the optical system. Compared with using the finished product provided by the manufacturer, that is, the well-spliced ​​detector array, the embodiment of the present invention splices and aligns to obtain an aligned spliced ​​detector, which not only reduces the purchase cost, but also can achieve wide-width imaging and ensure the imaging effect. At the same time, the operation is simple, and only the slit plate needs to be adjusted and the detectors need to be switched to obtain clear imaging on each detector, ensuring precise alignment.

[0057] Therefore, the collimator-based focal plane alignment method of the spliced ​​detector in the embodiment of the present invention can achieve precise alignment of the focal plane of the spliced ​​detector and is easy to operate, which can reduce the use cost of the spliced ​​detector while achieving wide-width imaging.

[0058] In one embodiment of the present invention, the method for aligning the focal plane of a stitched detector based on a parallel light tube also includes the following detection steps: reinstalling the corrected stitched detector on the infrared camera lens; switching to the first detector so that the slit forms a local image of the slit on the focal plane of the first detector, and adjusting the spacing distance between the corrected stitched detector and the infrared camera lens until the local image of the slit meets the requirements; switching to the next detector one by one so that the slit forms a local image of the slit on the focal plane of the next detector, and adjusting the field of view angle of the infrared camera lens until the local image of the slit meets the requirements.

[0059] Specifically, after the position of the detector is corrected, it needs to be further tested. The corrected spliced ​​detector is reinstalled on the infrared camera lens 4, and the position of the infrared camera lens 4 is adjusted so that the parallel light beam 6 collimated by the collimator 3 of the slit 2 is imaged on the first detector 51 on the infrared camera lens 4, and a local image of the slit is formed on the focal plane of the first detector 51. The interval between the corrected spliced ​​detector and the infrared camera lens 4 is adjusted, and the front-to-back distance of the corrected spliced ​​detector is specifically adjusted so that the local image of the slit meets the requirements, that is, the image is clear, and the image of the slit 2 can be recorded at the same time.

[0060] The position of the infrared camera lens 4 is adjusted so that the slit 2 is imaged on the second detector 52 to the eighth detector 58 successively. During each imaging, the field of view angle of the infrared camera lens 4 is adjusted so that the local imaging of the slit meets the requirements, that is, the imaging is clear.

[0061] In one example, the slit local imaging meeting the requirements may specifically include: the modulation transfer function (MTF) of the detector corresponding to the slit local imaging meeting a preset index. The preset index may be determined according to specific requirements, such as about 0.2.

[0062] The modulation transfer function of the detector is calculated by the following formula:

[0063]

[0064] Where MTF is the modulation transfer function of the detector, DN max is the pixel signal of the light-transmitting part of the slit, DN min is the pixel signal of the opaque part of the slit, and DN is the background noise of the detector.

[0065] Specifically, at each imaging, the modulation transfer function MTF of the detector is calculated. When the MTF meets the preset index, the adjustment of the front-back distance of the spliced ​​detector 5 and the position of the infrared camera lens 4 is stopped, that is, the overall focal plane adjustment of the spliced ​​detector 5 on the infrared camera lens 4 is completed. The adjusted spliced ​​detector 5 is mounted on the infrared camera lens 4 and applied to the field of short-wave infrared satellite remote sensing. The ground strip is imaged on the spliced ​​detector through the infrared camera payload, and wide-width detection can be achieved through push scanning in the along-track direction, thereby achieving two-dimensional ground area coverage.

[0066] Therefore, when using MTF as an evaluation indicator during alignment and subsequent testing, the results are consistent and objective even if different personnel are operating, which ensures the reliability of the evaluation imaging, thereby improving the alignment reliability and facilitating the precise arrangement of each detector.

[0067] In one embodiment of the present invention, referring to Figure 1 The alignment system further includes a five-dimensional adjustment frame 7, and the infrared camera lens 4 is arranged on the five-dimensional adjustment frame 7. The five-dimensional adjustment frame 7 is used to adjust the field angle of the infrared camera lens 4, and is also used to adjust the posture of the infrared camera lens 4. By adjusting the azimuth and pitch angle of the five-dimensional adjustment frame 7, different detectors are switched to perform imaging of the slit sheet 2; by adjusting the azimuth and pitch angle of the five-dimensional adjustment frame 7, the field angle of the infrared camera lens 4 is adjusted.

[0068] Specifically, in the above-mentioned alignment step (S1 to S3) and detection step, after the imaging of the first detector is completed, the azimuth and pitch angle of the five-dimensional adjustment frame 7 are adjusted to switch to the next detector (the second detector 52 to the eighth detector 58) one by one to image the slit 2. In the detection step, after switching to the next detector one by one and imaging, the azimuth and pitch angle of the five-dimensional adjustment frame 7 are adjusted to adjust the field of view angle of the infrared camera lens 4 until the local imaging of the slit corresponding to the current detector meets the requirements, that is, the adjustment is stopped when the MTF meets the preset index.

[0069] In one embodiment of the present invention, referring to Figure 1 The alignment system also includes a translation stage 8, on which the slit sheet 2 is disposed. The front-to-rear distance of the slit sheet 2 is adjusted by adjusting the horizontal position of the translation stage 8, so that the slit sheet 2 moves forward and backward, thereby adjusting the defocus amount of the slit sheet 2.

[0070] Specifically, in the alignment step S2, the slit sheet 2 is imaged on the focal planes of the second detector 52 to the eighth detector 58 one by one. During each imaging, the imaging may not be in the optimal position. The front-to-back distance of the slit sheet 2 is adjusted by adjusting the front-to-back position of the translation stage 8, so that the slit sheet 2 is defocused, and the defocus amount of the slit sheet 2 is adjusted. During the first imaging, i.e., imaging on the first detector 51, the slit sheet 2 is at the focal plane of the collimator 3, and the defocus amount is 0.

[0071] Therefore, the infrared camera lens and slit can be adjusted only through the five-dimensional adjustment frame and the translation stage, which helps to achieve precise alignment of the detector. The structure is simple, easy to implement and highly reliable.

[0072] Further, refer to Figure 1 The alignment system also includes a bandpass filter 9, which is placed between the light source 1 and the slit 2. After the light source 1 passes through the front bandpass filter 9, it is focused on the position of the slit 2. The light beam passing through the slit 2 is collimated by the collimation system 13 and then emitted in parallel. After the parallel light beam 6 is imaged by the infrared camera lens 4, a local image of the slit is formed on the focal plane of the detector.

[0073] In one embodiment of the present invention, the correction of the position of the corresponding detector based on the defocus amount of the slit in step S3 may include: calculating the defocus amount of the focal plane of the corresponding detector based on the defocus amount of the slit; grinding the support seat of the corresponding detector according to the defocus amount of the focal plane of the detector to achieve the correction of the axial position of the detector, and reinstalling each detector on the corresponding support seat after the correction to obtain a corrected spliced ​​detector.

[0074] Furthermore, calculating the defocus amount of the corresponding detector focal plane based on the defocus amount of the slit may include: recording the object distance of the slit, the image distance of the slit, and the object distance of the infrared camera lens and the image distance of the infrared camera lens when the slit is imaged on each detector focal plane; calculating the object distance relationship between the object distance of the slit and the object distance of the infrared camera lens, and the image distance relationship between the image distance of the slit and the image distance of the infrared camera lens based on all recorded results; calculating the defocus amount relationship between the defocus amount of the slit and the defocus amount of the detector focal plane based on the object distance relationship and the image distance relationship; and obtaining the defocus amount of the corresponding detector focal plane based on the defocus amount relationship and the defocus amount of each slit.

[0075] Specifically, the defocus amount of the slit corresponding to each detector is obtained through the alignment step, wherein the defocus amount of the first detector is 0, and the defocus amounts of the second to eighth detectors may not be 0. Moreover, the imaging conditions are recorded each time the image is clear, and the imaging conditions may include corresponding imaging parameters, such as the object distance and image distance of the slit, and the image distance and image distance of the infrared camera lens. Then, the relationship between the object distance of the slit and the object distance of the camera lens (which may be called the object distance relationship) and the relationship between the image distance of the slit and the image distance of the camera lens (which may be called the image distance relationship) are iteratively calculated based on the recorded parameters. Among them, when the object distance relationship and the image distance relationship are iteratively calculated, their mathematical relationships are:

[0076]

[0077] Among them, F is the focal length of the collimator, l is the object distance of the slit, and l' is the corresponding phase distance. s is the object distance of the infrared camera, s' is the corresponding image distance, n0 is the refractive index of the lens, n and n' are the refractive indices of the object side and image side of the lens respectively, and r1 and r2 are the curvature radii of the front and back surfaces of the lens respectively.

[0078] After iterative calculation, the corresponding imaging relationship between the object distance and the image distance can be calculated, and the relationship between the defocus of the slit (object distance focal amount) and the defocus of the detector focal plane (image distance focal amount) can be calculated based on the object distance relationship and the image distance relationship (which can be called the defocus relationship). When the second detector 52 to the eighth detector 58 are clearly imaged, the slit 2 has a defocus and is known. The defocus of the corresponding detector focal plane can be obtained by combining the defocus relationship, that is, the defocus of the focal plane of each detector (the second detector 52 to the eighth detector 58) relative to the focal plane of the infrared camera lens is obtained. In the specific calculation, the defocus of each detector can be simulated and calculated using ZEMAX software (including optical design software OpticStudio, OpticsBuilder, and OpticsViewer software). It should be noted that the defocus of the focal plane of the first detector is 0, which has been adjusted in step S1.

[0079] The defocus amount of each detector is the defocus amount relative to the focal plane of the first detector (that is, the focal plane of the camera lens). The defocus amount is used to simulate the relative position between each detector. Therefore, the spliced ​​detector 5 is detached from the camera, and the second detector 52 to the eighth detector 58 are removed from their respective support seats. According to each defocus amount, the support seats of the corresponding second detector 52 to the eighth detector 58 are respectively ground using a three-coordinate measuring machine (for example, the support seat of the second detector 52 is ground according to the defocus amount of the focal plane of the second detector 52). After grinding, the second detector 52 to the eighth detector 58 are reinstalled on their respective support seats in the original arrangement order to realize the correction of the axial position of the detector, realize the focal plane alignment, and obtain the corrected spliced ​​detector.

[0080] Therefore, the defocus of the slit pair at the focal plane of the collimator is used to simulate and calculate the defocus of the focal planes of different detectors, and the position of the detector is corrected accordingly, so as to achieve accurate arrangement of the detectors and ensure the performance of the optical system.

[0081] Based on the above description, it can be seen that the alignment principle of the embodiment of the present invention is:

[0082] Reference Figure 1 , after the collimator light source 1 passes through the front bandpass filter 9, it is focused on the position of the slit 2, and the width of the slit 2 is determined according to the specific optical system indicators. The light beam passing through the slit 2 is collimated by the collimator 3 collimation system 13 and then emitted in parallel. After the parallel light beam 6 is imaged by the infrared camera lens 4, the image plane of the slit is formed on the focal plane of the detector. When imaging on the focal plane of the first detector 51, adjust the interval between the spliced ​​detector 5 and the lens 4 until a clear image is obtained. By adjusting the azimuth and pitch angle of the five-dimensional adjustment frame 7, different detectors (the second detector 52 to the eighth detector 58) are switched one by one for imaging. Each time imaging occurs, since the focal planes of different detectors are not on the same plane, the defocus amount of the slit pair is controlled by adjusting the translation stage 8, so that clear images are obtained on the focal planes of different detectors. The defocus amount and imaging conditions of the slit pairs corresponding to each detector are recorded, and the defocus amount is converted through zemax simulation to obtain the defocus amount of the corresponding detector focal plane, and the axial position of the detector focal plane is adjusted to achieve alignment. Afterwards, the spliced ​​detector is reinstalled on the lens for imaging detection, and the field of view angle of the lens is adjusted again according to the MTF index requirements to achieve the alignment of the infrared camera.

[0083] The following is a description of the specific alignment and detection process of the present invention through a specific example:

[0084] (1)Reference Figure 1At the beginning, a slit sheet 2 with a customized slit width is placed at the focal plane of a collimator 3, and the slit sheet is placed on a translation stage 8. The slit sheet 2 can be moved back and forth along the focal plane by adjusting the translation stage 8, and a light source 1 such as a halogen lamp is used to illuminate the slit sheet 2;

[0085] (2)Reference Figure 1 , Figure 2 , eight detectors are mounted on a fixed bottom plate 59 (with a support seat thereon) to form a combination, namely a spliced ​​detector, and the spliced ​​detector is mounted on the short-wave infrared camera lens 4, and the lens is placed on a five-dimensional adjustment frame 7, and the azimuth and pitch angle of the five-dimensional adjustment frame 7 are adjusted to image the light beam collimated by the focal plane slit 2 through the parallel light tube 3 onto the first detector 51 of the infrared camera 15, and the image of the slit 2 through the infrared camera lens 4 is in a vertical relationship with the detector line array, and by adjusting the front and rear distance of the spliced ​​detector, the first detector 51 (line array detector) can clearly image the local slit, and the imaging of the slit pair is recorded at the same time;

[0086] (3) After the adjustment of the first linear detector 51 is completed, the azimuth and pitch angle of the five-dimensional adjustment frame 7 are adjusted to image the light beam collimated by the focal plane slit 2 through the parallel light tube 3 onto the second detector 52 of the infrared camera. The linear detector on the detector 52 may not be in the best position for imaging the local slit. By adjusting the position of the translation stage 8 and the front-to-back distance of the slit 2, the linear detector of the detector 52 can image the local slit clearly, and the defocus amount of the focal plane slit 2 when the detector 52 images clearly is recorded, and the imaging condition of the slit 2 is recorded at the same time;

[0087] (4) After the adjustment of the second linear detector 52 is completed, the azimuth and pitch angle of the five-dimensional adjustment frame 7 are adjusted to image the light beam of the focal plane slit 2 through the collimated light tube onto the third detector 53 of the infrared camera. The linear detector on the detector 53 may not be in the best position for imaging the local slit. By adjusting the position of the translation stage 8 and adjusting the front-to-back distance of the focal plane slit 2, the linear detector of the detector 53 can image the local slit clearly, and the defocus amount of the focal plane slit 2 when the detector 53 is clearly imaged is recorded, and the imaging condition of the slit 2 is recorded;

[0088] (5) According to steps (3) and (4), the corresponding tests of the focal planes of the eight detectors are completed in sequence, and the defocus of the focal plane slit 2 when the image is clear is recorded respectively, and the imaging condition of the slit 2 is recorded; the relationship between the object distance and the image distance between the slit and the focal plane of a single linear detector is iteratively calculated, so that the defocus relationship between the corresponding object distance focal amount (also called the collimator defocus amount, the slit defocus amount) and the image distance focal amount (also called the infrared camera lens defocus amount, the detector focal plane defocus amount) can be calculated according to the relationship between the object distance and the image distance. When the collimator is 4 mm, the defocus relationship curve can be shown as follows: Figure 4 As shown, the image distance focal amount (mm) can be obtained from the object distance focal amount (mm), that is, the defocus amount of each detector focal plane can be calculated by simulation using ZEMAX software, that is, the defocus amount of the 8 slits corresponds to the defocus amount of the 8 detector focal planes, where the defocus amount of the first slit and the defocus amount of the first detector are 0, and the following table is formed according to the corresponding relationship:

[0089] Table 1 Short-wave infrared detector focal plane control list

[0090] Slit plate defocus distance (mm) Corresponding MTF Corresponding lens defocus distance (mm) Detector 51 0 0 Detector 52 Detector 53 Detector 54 Detector 55 Detector 56 Detector 57 Detector 58

[0091] (6) According to the table recorded in step (5), the defocus amount of each detector is calculated by ZEMAX software simulation, and the eight linear detectors are corrected to the confocal plane position using a three-coordinate measuring machine. The second to eighth detectors are reinstalled on their respective support bases according to the corresponding numbers to obtain the corrected spliced ​​detectors;

[0092] (7) Install the corrected spliced ​​detector on the short-wave infrared camera lens 4 again, place the lens on the five-dimensional adjustment frame 7, adjust the azimuth and pitch angle of the five-dimensional adjustment frame 7 to image the light beam of the focal plane slit 2 through the collimated light tube on the short-wave infrared camera detector 51, and adjust the front and rear distance of the spliced ​​detector so that the detector 51 linear detector can clearly image the local slit, and record the imaging of the slit 2 at the same time. Adjust the azimuth and pitch angle of the five-dimensional adjustment frame 7 to image on detectors 52 to 59 in turn, record the imaging of the slit 2 on each detector, and calculate the MTF of all detectors. When the MTF does not meet the requirements, adjust the field of view angle of the lens 4 by adjusting the five-dimensional adjustment frame 7 until the MTF meets the requirements. When the MTF meets the requirements (for example, reaches 0.2), the overall adjustment of the focal plane is completed.

[0093] In summary, the embodiments of the present invention have the following technical effects:

[0094] First, the system equipment is simple, and only a slit sheet 2, a collimator 3 and a five-dimensional adjustment frame 8 are needed to achieve precise alignment of the focal plane of the spliced ​​detector;

[0095] Second, the method is simple to operate. It only requires adjusting the slit image plane to a clear position, recording the imaging conditions of detectors 51-58, and recording the defocus amount of slit 2 at the same time.

[0096] Third, the defocus of the infrared camera detector is calculated based on the defocus of the slit, and the position of the detector is adjusted accordingly to achieve alignment, thus ensuring the reliability of alignment;

[0097] Fourth, the evaluation index of the alignment adjustment method is the MTF index, which is highly objective, and the results are highly consistent when operated by different personnel, and the evaluation is reliable, thus ensuring the accurate alignment of the infrared camera detector.

[0098] Corresponding to the collimator-based focal plane alignment method of the spliced ​​detectors in the above embodiment, the present invention further provides a collimator-based focal plane alignment device for spliced ​​detectors, which is applied to an alignment system.

[0099] like Figure 1 As shown, the alignment system includes a light source 1, a slit plate 2, a collimator 3, an infrared camera lens 4 and a spliced ​​detector 5 comprising a plurality of detectors, the light source 1 is placed in front of the slit plate 2, the slit plate 2 is vertically placed at the focal plane of the collimator 3, and the spliced ​​detector 5 is mounted on the infrared camera lens 4.

[0100] The detector is a linear detector, and multiple detectors are mounted on a fixed base plate to obtain a combination, namely a spliced ​​detector 5. The fixed base plate has a support seat for mounting the detector, and each detector in the spliced ​​detector is located on a support seat. Figure 2 As shown, eight detectors (51-58) can be mounted on a fixed base plate 59 by fixing them on corresponding support seats to obtain a spliced ​​detector 5. That is, the spliced ​​detector 5 is a detector assembly that has only undergone preliminary assembly and installation of the detectors but has not been aligned.

[0101] Figure 5 It is a block diagram of a focal plane alignment device of a spliced ​​detector based on a collimator according to an embodiment of the present invention.

[0102] like Figure 5 As shown, the collimator-based spliced ​​detector focal plane alignment device includes a first adjustment module 10 , a second adjustment module 20 and a correction module 30 .

[0103] Among them, the first adjustment module 10 is used to make the slit piece form a local image of the slit piece on the focal plane of the first detector after passing through the collimator and the infrared camera lens in sequence, and adjust the spacing distance between the spliced ​​detector and the infrared camera lens until the local image of the slit piece meets the requirements; the second adjustment module 20 is used to switch to the next detector, so that the slit piece forms a local image of the slit piece on the focal plane of the next detector after passing through the collimator and the infrared camera lens in sequence, adjust the position of the slit piece until the local image of the slit piece meets the requirements, record the defocus amount of the slit piece corresponding to the next detector, return to the second step, until the defocus amount of the slit piece corresponding to the last detector is obtained; the correction module 30 is used to correct the position of the corresponding detector based on the defocus amount of the slit piece, and obtain a corrected spliced ​​detector to achieve alignment of the detector focal plane.

[0104] In one embodiment of the present invention, the collimator-based focal plane alignment device for spliced ​​detectors further includes a mounting module, a third adjustment module and a fourth adjustment module.

[0105] The installation module is used to reinstall the corrected spliced ​​detector on the infrared camera lens; the third adjustment module is used to switch to the first detector so that the slit piece forms a local slit image on the focal plane of the first detector, and adjust the spacing distance between the corrected spliced ​​detector and the infrared camera lens until the local slit image meets the requirements; the fourth adjustment module is used to switch to the next detector in sequence so that the slit piece forms a local slit image on the focal plane of the next detector, and adjust the field of view angle of the infrared camera lens until the local slit image meets the requirements.

[0106] In one embodiment of the present invention, the correction module 30 includes a calculation unit and a correction unit.

[0107] The calculation unit is used to calculate the defocus amount of the focal plane of the corresponding detector based on the defocus amount of the slit; the correction unit is used to grind the support seat of the corresponding detector according to the defocus amount of the focal plane of the detector to realize the correction of the axial position of the detector, and reinstall each detector on the corresponding support seat after correction to obtain a corrected spliced ​​detector.

[0108] Furthermore, the computing unit is specifically used for:

[0109] When the slit is imaged on each detector focal plane, the object distance of the slit, the image distance of the slit, the object distance of the infrared camera lens, and the image distance of the infrared camera lens are recorded; based on all the recorded results, the object distance relationship between the object distance of the slit and the object distance of the infrared camera lens, and the image distance relationship between the image distance of the slit and the image distance of the infrared camera lens are calculated; according to the object distance relationship and the image distance relationship, the defocus amount relationship between the defocus amount of the slit and the defocus amount of the detector focal plane is calculated; according to the defocus amount relationship and the defocus amount of each slit, the defocus amount of the corresponding detector focal plane is obtained.

[0110] It should be noted that the specific implementation of the focal plane alignment device of the spliced ​​detector based on a collimator can refer to the specific implementation of the focal plane alignment method of the spliced ​​detector based on a collimator mentioned above, and will not be described in detail here to avoid redundancy.

[0111] The collimator-based focal plane alignment device for spliced ​​detectors according to the embodiment of the present invention can achieve precise alignment of the focal plane of the spliced ​​detectors and is easy to operate. It can reduce the use cost of the spliced ​​detectors while achieving wide-width imaging.

[0112] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations on the present invention, and those of ordinary skill in the art can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for aligning the focal plane of a spliced ​​detector based on a collimator, characterized in that: The method is applied to an alignment system, the alignment system comprises a light source, a collimator, a slit, an infrared camera lens and a spliced ​​detector comprising a plurality of detectors, the light source is placed in front of the slit, the slit is placed vertically at the focal plane of the collimator, the spliced ​​detector is mounted on the infrared camera lens, and the method comprises the following steps: The slit sheet is made to form a local image of the slit sheet on the focal plane of the first detector after passing through the collimator and the infrared camera lens in sequence, and the spacing distance between the spliced ​​detector and the infrared camera lens is adjusted until the local image of the slit sheet meets the requirements; Switch to the next detector, so that the slit sheet forms a local image of the slit sheet on the focal plane of the next detector after passing through the collimator and the infrared camera lens in sequence, adjust the position of the slit sheet until the local image of the slit sheet meets the requirements, record the defocus amount of the slit sheet corresponding to the next detector, and return to the second step until the defocus amount of the slit sheet corresponding to the last detector is obtained; The position of the corresponding detector is corrected based on the defocus amount of the slit sheet to obtain a corrected spliced ​​detector, so as to achieve alignment of the focal plane of the detector.

2. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to claim 1, characterized in that: Also includes: reinstalling the modified spliced ​​detector on the infrared camera lens; Switching to the first detector so that the slit forms a local slit image on the focal plane of the first detector, and adjusting the spacing distance between the corrected spliced ​​detector and the infrared camera lens until the local slit image meets the requirements; Switch to the next detector one by one so that the slit forms a local image of the slit on the focal plane of the next detector, and adjust the field of view angle of the infrared camera lens until the local image of the slit meets the requirements.

3. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to claim 1, characterized in that: When the light beam collimated by the slit plate passes through the collimator and is emitted in parallel to the infrared camera lens, the image formed in the infrared camera lens is perpendicular to the first detector.

4. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to claim 1, characterized in that: The requirement of the local imaging of the slit sheet being satisfied specifically includes: a modulation transfer function of a detector corresponding to the local imaging of the slit sheet being satisfied by a preset index.

5. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to claim 4, characterized in that: The modulation transfer function of the detector is calculated by the following formula: Where MTF is the modulation transfer function of the detector, DN max is the pixel signal of the light-transmitting part of the slit, DN min is the pixel signal of the opaque part of the slit, and DN is the background noise of the detector.

6. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to claim 2, characterized in that: The alignment system also includes a five-dimensional adjustment frame, and the infrared camera lens is arranged on the five-dimensional adjustment frame. By adjusting the azimuth and pitch angle of the five-dimensional adjustment frame, different detectors are switched to image the slit sheet; by adjusting the azimuth and pitch angle of the five-dimensional adjustment frame, the field of view angle of the infrared camera lens is adjusted.

7. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to claim 1, characterized in that: The alignment system further comprises a translation stage, the slit sheet is arranged on the translation stage, and the front-to-back distance of the slit sheet is adjusted by adjusting the horizontal position of the translation stage, thereby adjusting the defocus amount of the slit sheet.

8. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to any one of claims 1 to 7, characterized in that: Each of the detectors is located on a support seat respectively, and the position of the corresponding detector is corrected based on the defocus amount of the slit sheet, including: Calculating the defocus amount of the focal plane of the corresponding detector based on the defocus amount of the slit; The support seat of the corresponding detector is ground according to the defocus amount of the focal plane of the detector to correct the axial position of the detector, and after the correction, each detector is reinstalled on the corresponding support seat to obtain a corrected spliced ​​detector.

9. The method for aligning the focal plane of a spliced ​​detector based on a collimator according to claim 8, characterized in that: Calculating the defocus amount of the focal plane of the corresponding detector based on the defocus amount of the slit sheet includes: When the slit is imaged on each detector focal plane, the object distance of the slit, the image distance of the slit, the object distance of the infrared camera lens, and the image distance of the infrared camera lens are recorded; Based on all the recorded results, the object distance relationship between the slit sheet object distance and the infrared camera lens object distance and the image distance relationship between the slit sheet image distance and the infrared camera lens image distance are calculated; Calculating a defocus amount relationship between a defocus amount of a slit sheet and a defocus amount of a focal plane of a detector according to the object distance relationship and the image distance relationship; The defocus amount of the corresponding detector focal plane is obtained according to the defocus amount relationship and the defocus amount of each slit.

10. A focal plane alignment device for a spliced ​​detector based on a collimator, characterized in that: Applied to an alignment system, the alignment system comprises a light source, a collimator, a slit, an infrared camera lens and a spliced ​​detector comprising a plurality of detectors, the light source is placed in front of the slit, the slit is vertically placed at the focal plane of the collimator, the spliced ​​detector is mounted on the infrared camera lens, and the device comprises: A first adjustment module is used to make the slit sheet form a local image of the slit sheet on the focal plane of the first detector after passing through the collimator and the infrared camera lens in sequence, and to adjust the spacing distance between the spliced ​​detector and the infrared camera lens until the local image of the slit sheet meets the requirements; The second adjustment module is used to switch to the next detector, so that the slit sheet forms a local image of the slit sheet on the focal plane of the next detector after passing through the collimator and the infrared camera lens in sequence, adjust the position of the slit sheet until the local image of the slit sheet meets the requirements, record the defocus amount of the slit sheet corresponding to the next detector, and return to the second step until the defocus amount of the slit sheet corresponding to the last detector is obtained; The correction module is used to correct the position of the corresponding detector based on the defocus amount of the slit sheet to obtain a corrected spliced ​​detector to achieve alignment of the focal plane of the detector.

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