A system and method for testing an interior orientation element of a camera system

Abstract

The application discloses a system and method for testing internal azimuth elements of a camera system, which comprises a plane mirror, a first target, a second target, a first illumination light source, a second illumination light source, a six-degree-of-freedom turntable and a ground detection system; wherein the first target and the second target are arranged at the focal plane position of the camera system, and the first target and the second target are symmetric along the center of the focal plane detector of the camera system; the camera system is arranged on the six-degree-of-freedom turntable; and the ground detection system is connected with the focal plane detector of the camera system. The application discards the parallel light pipe and the autocollimator, and improves the testing precision.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical remote sensor testing, and particularly relates to a system and method for testing interior orientation elements of a camera system. BACKGROUND

[0002] In order to accurately describe the precise position of a spatial point by image information, it is necessary to precisely calibrate the interior orientation elements of an optical remote sensor, and high-precision testing of the interior orientation elements can provide guarantee for the mapping and positioning accuracy of a satellite.

[0003] The prior art generally uses a precision angle measurement method to complete the testing of the interior orientation elements. As described in the invention patent CN202010703613.7, the tested camera needs to be rotated by a plurality of fixed angles relative to a collimator during testing, so that the target of the collimator is imaged at different positions on the focal plane of the tested camera, and the interior orientation elements of the tested camera can be calculated through the rotation angle value and the displacement of the target image on the focal plane.

[0004] However, with the increase of the resolution of the camera, the focal length of the camera is getting longer and the aperture is getting larger, and the aperture can even reach more than 2m. When using the traditional precision angle measurement method device to test the high-precision interior orientation elements of a large optical remote sensor with long focal length and large width, it is necessary to ensure that the aperture of the collimator can completely cover the entrance pupil of the tested camera at any measurement point position. As described in the invention patent CN102494698B, the focal length of a high-resolution remote sensor is long, and the entrance pupil position is further away from the rear of the lens. If the existing testing method is used, the entrance pupil position of the remote sensor needs to be placed at the center of the rotation shaft of a high-precision two-dimensional turntable, and a very large high-precision two-dimensional turntable is needed to rotate the tested camera around the entrance pupil. In addition, a self-collimation instrument is needed to calibrate the positions of the collimator and the camera, and the aperture size of the collimator needs to be very large. This puts a very large requirement on the scale of the interior orientation element testing device. In addition, a considerable part of large-aperture and super-large-aperture cameras use vertical installation and adjustment, and the camera cannot be placed horizontally. For large-aperture cameras with vertical installation and detection, a vertical large-aperture collimator and a vertical autocollimator are needed for testing. The vertical large-aperture collimator is a complete set of large equipment, and its design, development, erection and calibration are very inconvenient. SUMMARY

[0005] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide a system and method for testing the interior orientation elements of a camera system, which discards the collimator and autocollimator and improves the testing precision.

[0006] The application is achieved by the following technical scheme: a system for testing interior orientation elements of a camera system, comprising: a plane mirror, a first target, a second target, a first illumination light source, a second illumination light source, a six-degree-of-freedom turntable and a ground detection system; wherein the first target and the second target are arranged at the focal plane position of the camera system, and the first target and the second target are symmetric along the center of the focal plane detector of the camera system; the camera system is arranged on the six-degree-of-freedom turntable; the ground detection system is connected with the focal plane detector of the camera system; the light source emitted by the first illumination light source becomes first parallel light with target information after passing through the first target and the camera system; the first parallel light enters the camera system after being reflected by the plane mirror to reach the focal plane detector of the camera system, and the ground detection system collects the imaging information of the focal plane detector to obtain a first target image; the light source emitted by the second illumination light source becomes second parallel light with target information after passing through the second target and the camera system; the second parallel light enters the camera system after being reflected by the plane mirror to reach the focal plane detector of the camera system, and the ground detection system collects the imaging information of the focal plane detector to obtain a second target image; the ground detection system: collects the imaging information of the focal plane detector to obtain the first target image and the second target image, respectively calculates the centroid of the first target image and the centroid of the second target image, and obtains the principal point according to the centroid of the first target image and the centroid of the second target image.

[0007] In the above system for testing interior orientation elements of a camera system, the second illumination light source is turned off, the six-degree-of-freedom turntable is rotated by an angle W i along the linear array direction, the light source emitted by the first illumination light source becomes third parallel light with target information after passing through the first target and the camera system; the third parallel light enters the camera system after being reflected by the plane mirror to reach the focal plane detector of the camera system; the ground detection system: collects the imaging information of the focal plane detector to obtain a third target image, calculates the centroid of the third target image, and obtains target image centroid displacement L i according to the centroid of the first target image and the centroid of the third target image; and obtains distortion and principal distance according to the angle W i and the target image centroid displacement L i .

[0008] In the above system for testing interior orientation elements of a camera system, the average center point of the centroid of the first target image and the centroid of the second target image is the principal point.

[0009] In the above system for testing interior orientation elements of a camera system, the distortion is obtained by the following formula:

[0010] D i =Li -f tgW i +p tg 2 W i ;

[0011] wherein D i is the distortion of the i-th field, L i is the theoretical image height of the i-th field, f is the focal length, W i is the rotation angle of the six-degree-of-freedom rotary table along the linear array direction, p is the position of the principal point, and i is the number of the field.

[0012] In the system for testing the interior orientation elements of the camera system, the focal length is obtained by the following formula:

[0013]

[0014] wherein f is the focal length, L i is the theoretical image height of the i-th field, W i is the rotation angle of the six-degree-of-freedom rotary table along the linear array direction, and i is the number of the field.

[0015] In the system for testing the interior orientation elements of the camera system, the camera system comprises a lens, a focal plane support assembly and a focal plane detector; one end of the lens is connected to one end of the focal plane support assembly; and the focal plane detector is arranged on the light-sensitive surface of the focal plane support assembly.

[0016] In the system for testing the interior orientation elements of the camera system, the light-etching surfaces of the first target and the second target are located in the same plane as the light-sensitive surface of the focal plane support assembly; the light-etching surfaces of the first target and the second target are both etched with light-passing slits, and the width of the light-passing slits is equal to the size of the image element of the focal plane detector.

[0017] A method for testing the interior orientation elements of a camera system, comprising: turning on a first illumination light source and a second illumination light source; the light emitted by the first illumination light source becomes first parallel light with target information after passing through a first target and the camera system; the first parallel light enters the camera system after being reflected by a plane mirror and reaches a focal plane detector of the camera system; the light emitted by the second illumination light source becomes second parallel light with target information after passing through a second target and the camera system; the second parallel light enters the camera system after being reflected by the plane mirror and reaches the focal plane detector of the camera system; a ground detection system collects imaging information of the focal plane detector to obtain a second target image; the ground detection system respectively calculates the centroids of a first target image and a second target image to obtain the centroid of the first target image and the centroid of the second target image; and a principal point is obtained according to the centroid of the first target image and the centroid of the second target image; the second illumination light source is turned off; a six-degree-of-freedom rotary table is rotated along a linear array direction; and the angle W iThe light emitted by the first illumination source passes through the first target and the camera system, becoming a third parallel light carrying target information. This third parallel light is reflected by a plane mirror and enters the camera system, reaching the focal plane detector. The ground detection system acquires the imaging information from the focal plane detector to obtain the third target image. The ground detection system calculates the centroid of the third target image and, based on the centroids of the first and third target images, obtains the target image centroid displacement L. i According to angle W i And the target image centroid displacement L i The distortion and principal distance are obtained.

[0018] In the above method for testing the orientation elements within a camera system, the distortion is obtained using the following formula:

[0019] D i =L i -f·tgW i +p·tg 2 W i ;

[0020] Among them, D i For the distortion corresponding to the i-th field of view, L i Let f be the theoretical image height of the i-th field of view, f be the principal distance, and W be the theoretical image height of the i-th field of view. i Let p be the rotation angle of the six-degree-of-freedom turntable along the linear array direction, p be the position of the principal point, and i be the field of view number.

[0021] In the above method for testing the orientation elements within a camera system, the principal distance is obtained using the following formula:

[0022]

[0023] Where f is the principal distance, L i Let W be the theoretical image height of the i-th field of view. i Let i be the rotation angle of the six-degree-of-freedom turntable along the linear array direction, and i be the field of view number.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention does not require the use of a collimator and additional autocollimating instruments. The internal orientation element test can be achieved by using the plane mirror system required by the camera assembly and testing equipment.

[0026] (2) The present invention uses the self-collimation principle, which improves the accuracy of detection alignment during the detection alignment process. Attached Figure Description

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not intended to limit the present application thereto. Like reference numerals are used to indicate like elements throughout the several views. In the drawings:

[0028] Figure 1 is a schematic diagram of a system for testing an internal orientation element of a camera system according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] Exemplary embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0030] Figure 1 is a schematic diagram of a system for testing an internal orientation element of a camera system according to an embodiment of the present application. As shown in Figure 1 the system for testing an internal orientation element of a camera system includes a plane mirror 1, a first target 51, a second target 52, a first illumination light source 61, a second illumination light source 62, a six-degree-of-freedom turntable 7, and a ground detection system 8. Among them,

[0031] The first target 51 and the second target 52 are both arranged at the focal plane position of the camera system, and the first target 51 and the second target 52 are symmetrically arranged along the center of the focal plane detector of the camera system; the camera system is arranged on the six-degree-of-freedom turntable 7; and the ground detection system 8 is connected to the focal plane detector of the camera system.

[0032] The light emitted by the first illumination light source 61 becomes first parallel light with target information after passing through the first target 51 and the camera system; the first parallel light enters the camera system after being reflected by the plane mirror 1 to reach the focal plane detector of the camera system, and the ground detection system 8 collects the imaging information of the focal plane detector to obtain the first target image.

[0033] The light emitted by the second illumination light source 62 becomes second parallel light with target information after passing through the second target 52 and the camera system; the second parallel light enters the camera system after being reflected by the plane mirror 1 to reach the focal plane detector of the camera system, and the ground detection system 8 collects the imaging information of the focal plane detector to obtain the second target image.

[0034] The ground detection system 8 calculates the centroids of the first target image and the second target image respectively, and obtains the principal point based on the centroids of the first target image and the second target image.

[0035] The second illumination source 62 is turned off, and the six-degree-of-freedom turntable 7 rotates by an angle W along the linear array direction. i The light emitted by the first illumination source 61 passes through the first target 51 and the camera system, becoming a third parallel light carrying target information. This third parallel light is reflected by the plane mirror 1 and enters the camera system, reaching the focal plane detector. The ground detection system 8 acquires the imaging information from the focal plane detector to obtain a third target image. The centroid of the third target image is calculated. Based on the centroids of the first and third target images, the target image centroid displacement L is obtained. i According to angle W i And the target image centroid displacement L i The distortion and principal distance are obtained.

[0036] The distortion is obtained using the following formula:

[0037] D i =L i -f·tgW i +p·tg 2 W i ;

[0038] Among them, D i For the distortion corresponding to the i-th field of view, L i Let f be the theoretical image height of the i-th field of view, f be the principal distance, and W be the theoretical image height of the i-th field of view. i Let p be the rotation angle of the six-degree-of-freedom turntable 7 along the linear array direction, p be the position of the principal point, and i be the field of view number.

[0039] The principal distance is obtained using the following formula:

[0040]

[0041] Where f is the principal distance, L i Let W be the theoretical image height of the i-th field of view. i Let i be the rotation angle of the six-degree-of-freedom turntable 7 along the linear array direction, and i be the field of view number.

[0042] like Figure 1 As shown, the camera system includes a lens 2, a focal plane support assembly 3, and a focal plane detector 4; wherein, one end of the lens 2 is connected to one end of the focal plane support assembly 3; and the focal plane detector 4 is disposed on the photosensitive surface of the focal plane support assembly 3.

[0043] The light-etching surface of the first target 51 and the light-etching surface of the second target 52 are located in the same plane as the light-sensitive surface of the focal plane support assembly 3; the light-etching surface of the first target 51 and the light-etching surface of the second target 52 are both etched with a light-passing slit, and the width of the light-passing slit is equal to the size of the image element of the focal plane detector 4. The center of the focal plane detector 4 coincides with the center of the light-sensitive surface of the focal plane support assembly 3. The central axis of the six-degree-of-freedom turntable 7 coincides with the central axis of the camera system.

[0044] The autocollimation principle refers to that when a light-emitting point (object) is located at the focal plane of an optical system, the light emitted by the light-emitting point will become a parallel light after passing through the optical system. If a plane mirror perpendicular to the optical axis is placed in front of the optical system, the parallel light will be reflected back by the plane mirror, and the reflected light will still converge on the focal plane of the optical system after passing through the optical system again, and the converging point will be located at the symmetrical position of the light-emitting point relative to the optical axis.

[0045] The autocollimation plane mirror 1 is a plane mirror with an aperture larger than the entrance pupil of the camera, and is placed in front of the camera system. The mirror surface is better than 1 / 50λ.

[0046] Before the lens 2 of the space camera system is connected with the focal plane assembly 3 of the space camera system, the first target 51 and the second target 52 are spliced on the focal plane detector of the space camera system by using a splicing instrument.

[0047] The light-etching surface of the first target 51 and the light-etching surface of the second target 52 are located in the same plane as the light-sensitive surface of the focal plane detector of the space camera system; the light-etching surface of the first target 51 and the light-etching surface of the second target 52 are both etched with a light-passing slit, and the width of the light-passing slit is equal to the size of the image element of the focal plane detector of the space camera system; and the TDI integration direction of the TDI integrated focal plane detector of the space camera system is parallel. The light-passing slit of the first target 51 and the light-passing slit of the second target 52 are equal to the size of the image element of the focal plane detector 4 of the space camera system. The first target 51 and the second target 52 are completely symmetrical relative to the center of the detector by using the splicing instrument, and the error depends on the splicing accuracy.

[0048] The first illumination light source 61 and the second illumination light source 62 provide light sources for the camera system, and the illumination light source is generally an integrating sphere.

[0049] The six-degree-of-freedom turntable 7 is used to support the camera and adjust the position of the camera, and is mainly used to adjust the angle of the camera, and the precision reaches 1″.

[0050] The embodiment also provides a method for testing the orientation elements in the camera system, and the method comprises the following steps:

[0051] Step S100: turn on the first illuminating light source 61 and the second illuminating light source 62, the light emitted by the first illuminating light source 61 passes through the first target 51 and the camera system to become the first parallel light with target information; the first parallel light is reflected by the plane mirror 1 and then enters the camera system to reach the focal plane detector of the camera system;

[0052] Step S200: the light emitted by the second illuminating light source 62 passes through the second target 52 and the camera system to become the second parallel light with target information; the second parallel light is reflected by the plane mirror 1 and then enters the camera system to reach the focal plane detector of the camera system, and the ground detection system 8 collects the imaging information of the focal plane detector to obtain the second target image;

[0053] Step S300: the ground detection system 8 respectively calculates the centroids of the first target image and the second target image to obtain the centroid of the first target image and the centroid of the second target image, and obtains the principal point according to the centroid of the first target image and the centroid of the second target image;

[0054] Step S400: turn off the second illuminating light source 62, rotate the six-degree-of-freedom rotating table 7 along the linear array direction, and record the angle W i rotated by the camera system Figure 1 , the light emitted by the first illuminating light source 61 passes through the first target 51 and the camera system to become the third parallel light with target information; the third parallel light is reflected by the plane mirror 1 and then enters the camera system to reach the focal plane detector of the camera system, and the ground detection system 8 collects the imaging information of the focal plane detector to obtain the third target image; wherein, as shown in Figure 1 , the linear array direction is perpendicular to the paper surface.

[0055] Step S500: the ground detection system 8 calculates the centroid of the third target image to obtain the centroid of the third target image, and obtains the target image centroid displacement L i according to the angle W i and the target image centroid displacement L i obtains the distortion and the principal distance.

[0056] Specifically, before step S100, the following steps are further included:

[0057] In the focal plane position of the space camera system, the first target 51 and the second target 52 are arranged, the first target 51 and the second target 52 are spliced with the focal plane detector 4 on the focal plane assembly 3 of the space camera system by using a splicer, the photoetching surface of the first target 51 and the second target 52 is located in the same plane as the photosensitive surface of the focal plane detector 4 of the camera system; the plane mirror 1 is arranged on the light inlet side of the camera system; the first illuminating light source 61 and the second illuminating light source 62 are respectively placed on the back surfaces of the first target 51 and the second target 52. The camera system is connected with the ground detection system 8.

[0058] Because the first target image and the second target image are not strictly symmetrical with the center of the focal plane detector 4 in the actual operation process, the six-degree-of-freedom rotary table 7 is adjusted to make the optical axis of the lens 2 rotate in a small range, and the imaging condition of the detector 4 is detected until two symmetrical target images appear on the detector 4.

[0059] The present application does not need to use a collimator and additional autocollimation instruments, and can realize the test of the interior orientation elements by using the plane mirror system required by the camera adjustment detection device; the present application uses the autocollimation principle, and improves the detection and alignment accuracy in the detection and alignment process.

[0060] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not depart from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. A system for testing orientation elements within a camera system, characterized in that... include: Plane reflector (1), first target (51), second target (52), first illumination source (61), second illumination source (62), six-degree-of-freedom turntable (7), and ground detection system (8); among which, The first target (51) and the second target (52) are both located at the focal plane of the camera system, and the first target (51) and the second target (52) are symmetrical about the center of the focal plane detector of the camera system. The camera system is mounted on the six-degree-of-freedom turntable (7); The ground detection system (8) is connected to the focal plane detector of the camera system; The light emitted by the first illumination source (61) becomes the first parallel light carrying target information after passing through the first target (51) and the camera system; the first parallel light enters the camera system after being reflected by the plane mirror (1) and reaches the focal plane detector of the camera system; the ground detection system (8) collects the imaging information of the focal plane detector to obtain the first target image. The light emitted by the second illumination source (62) becomes a second parallel light carrying target information after passing through the second target (52) and the camera system; The second parallel light is reflected by the plane mirror (1) and enters the camera system to reach the focal plane detector of the camera system. The ground detection system (8) collects the imaging information of the focal plane detector to obtain the second target image. The ground detection system (8) collects imaging information from the focal plane detector to obtain a first target image and a second target image, calculates the centroid of the first target image and the second target image respectively, and obtains the principal point based on the centroid of the first target image and the second target image.

2. The system for testing the orientation elements within a camera system according to claim 1, characterized in that: The second lighting source (62) is turned off, and the six-degree-of-freedom turntable (7) rotates by an angle W along the linear array direction. i The light emitted by the first illumination source (61) becomes a third parallel light carrying target information after passing through the first target (51) and the camera system; the third parallel light is reflected by the plane mirror (1) and enters the camera system to reach the focal plane detector of the camera system. The ground detection system (8) acquires the imaging information of the focal plane detector to obtain the third target image, calculates the centroid of the third target image, and obtains the centroid of the third target image based on the centroid of the first target image and the centroid of the third target image; and obtains the target image centroid displacement L based on the centroid of the first target image and the centroid of the third target image. i According to angle W i And the target image centroid displacement L i The distortion and principal distance are obtained.

3. The system for testing the orientation elements within a camera system according to claim 1, characterized in that: The centroid of the first target image and the average center point of the centroid of the second target image are the principal points.

4. The system for testing the orientation elements within a camera system according to claim 2, characterized in that: The distortion is obtained using the following formula: D i =L i -f·tgW i +p·tg 2 W i ; Among them, D i For the distortion corresponding to the i-th field of view, L i Let f be the theoretical image height of the i-th field of view, f be the principal distance, and W be the theoretical image height of the i-th field of view. i Let p be the rotation angle of the six-degree-of-freedom turntable (7) along the linear array direction, p be the position of the principal point, and i be the field of view number.

5. The system for testing the orientation elements within a camera system according to claim 2, characterized in that: The principal distance is obtained using the following formula: Where f is the principal distance, L i Let W be the theoretical image height of the i-th field of view. i Let i be the angle of rotation of the six-degree-of-freedom turntable (7) along the linear array direction, and i be the field of view number.

6. The system for testing the orientation elements within a camera system according to claim 1, characterized in that: The camera system includes a lens (2), a focal plane support assembly (3), and a focal plane detector (4); wherein, One end of the lens (2) is connected to one end of the focal plane support assembly (3); The focal plane detector (4) is disposed on the photosensitive surface of the focal plane support assembly (3).

7. The system for testing the orientation elements within a camera system according to claim 6, characterized in that: The photolithographic surface of the first target (51) and the photolithographic surface of the second target (52) are located on the same plane as the photosensitive surface of the focal plane support assembly (3); The photolithographic surfaces of the first target (51) and the second target (52) are both engraved with light-transmitting slits, and the width of the light-transmitting slits is equal to the pixel size of the focal plane detector (4).

8. A method for testing the azimuth elements within a camera system according to any one of claims 1-7, characterized in that... include: Turn on the first illumination source (61) and the second illumination source (62). The light emitted by the first illumination source (61) becomes the first parallel light carrying target information after passing through the first target (51) and the camera system. The first parallel light enters the camera system and reaches the focal plane detector of the camera system after being reflected by the plane mirror (1). The light emitted by the second illumination source (62) becomes a second parallel light carrying target information after passing through the second target (52) and the camera system; The second parallel light is reflected by the plane mirror (1) and enters the camera system to reach the focal plane detector of the camera system. The ground detection system (8) collects the imaging information of the focal plane detector to obtain the second target image. The ground detection system (8) calculates the centroids of the first target image and the second target image respectively, and obtains the centroids of the first target image and the second target image. Based on the centroids of the first target image and the second target image, the principal point is obtained. Turn off the second illumination source (62), rotate the six-degree-of-freedom turntable (7) along the linear array direction, and record the angle W rotated by the camera system. i The light emitted by the first illumination source (61) becomes the third parallel light carrying target information after passing through the first target (51) and the camera system. The third parallel light enters the camera system after being reflected by the plane mirror (1) and reaches the focal plane detector of the camera system. The ground detection system (8) collects the imaging information of the focal plane detector to obtain the third target image. The ground detection system (8) calculates the centroid of the third target image and obtains the centroid of the third target image. Based on the centroids of the first and third target images, it obtains the target image centroid displacement L. i According to angle W i And the target image centroid displacement L i The distortion and principal distance are obtained.

9. The method for testing the orientation elements within a camera system according to claim 8, characterized in that: The distortion is obtained using the following formula: D i =L i -f·tgW i +p·tg 2 W i ; Among them, D i For the distortion corresponding to the i-th field of view, L i Let f be the theoretical image height of the i-th field of view, f be the principal distance, and W be the theoretical image height of the i-th field of view. i Let p be the rotation angle of the six-degree-of-freedom turntable (7) along the linear array direction, p be the position of the principal point, and i be the field of view number.

10. The method for testing the orientation elements within a camera system according to claim 8, characterized in that: The principal distance is obtained using the following formula: Where f is the principal distance, L i Let W be the theoretical image height of the i-th field of view. i Let i be the angle of rotation of the six-degree-of-freedom turntable (7) along the linear array direction, and i be the field of view number.

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