An infrared lens refrigeration type detector cold light shield testing device and method

Abstract

An infrared lens refrigeration type detector cold light screen test device and method, the device comprises a high temperature black body, a black body blocking piece, a two-dimensional linear guide rail and a cold light screen two-dimensional adjustment mechanism; the high temperature black body is used for simulating an infrared target, the infrared target is transmitted to an infrared detector through an optical system; the detector has a built-in cold light screen for continuously obtaining cold light screen test results; the black body blocking piece is used for blocking the light outlet diameter of the black body; the two-dimensional linear guide rail is used for driving the black body target to perform two-dimensional scanning in front of the lens, and the linear guide rail movement stroke covers the full aperture of the lens; the cold light screen two-dimensional adjustment mechanism is used for performing two-dimensional precise adjustment on the cold light screen according to the cold light screen test results, and the adjustment precision is better than 0.05 mm. The adjustment method using the above device is simple to operate, the cold light screen matching efficiency criterion is clear, and manual operation or full automatic operation is compatible, so that the device can be used for batch research and production lines of infrared lenses and has a wide application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of infrared optical imaging technology, in particular to a kind of infrared lens refrigeration type detector cold stop testing device and method. BACKGROUND

[0002] With the development of optical technology, infrared imaging optical system has obtained more and more applications in advanced optical instruments, aerospace, military, medicine and other aspects. In the infrared refrigeration detector, stray radiation can cause the image contrast of the system to decrease, lose the high frequency signal of the target and color distortion, etc., thereby affecting the spatial detection distance and resolution capability of the detector. Therefore, for high-precision infrared refrigeration detector, the suppression of stray radiation is particularly crucial.

[0003] In the infrared refrigeration detector, since the infrared radiation is detected, when the detector receives the radiation, the area other than the target will radiate energy, especially the metal parts outside the cold stop that are not refrigerated, thus causing interference to the detector. In order to avoid such problems, a cold stop is usually placed in front of the detector chip to limit the transmission of stray radiation energy. The cold stop, i.e. the traditional cold screen, is an important component in the Dewar, mainly serving to limit the field of view, reduce the background light flux and reduce the background noise, thereby improving the signal-to-noise ratio of the detector chip.

[0004] When designing an optical system, the system exit pupil is usually designed as a real exit pupil, located in front of the detector and completely coinciding with the cold stop, to achieve the highest cold stop matching efficiency, improve the signal-to-noise ratio of the detector, and thus improve the sensitivity of the infrared refrigeration detector.

[0005] However, there is currently a lack of effective methods for testing and adjusting the cold stop matching effect, and it is necessary to design an effective device and method to solve the problem of testing and adjusting the cold stop of the infrared lens refrigeration detector. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and solve the problem of testing and adjusting the cold stop of the infrared lens refrigeration detector.

[0007] The purpose of the present application is achieved by the following technical solutions:

[0008] An infrared lens refrigeration type detector cold stop testing device, comprising a high-temperature blackbody, a blackbody blocking piece, a two-dimensional linear guide rail and a cold stop two-dimensional adjustment mechanism.

[0009] The high-temperature blackbody is used to simulate an infrared target, and the infrared target transmits energy to an infrared detector through an optical system. The detector has a built-in cold stop for continuously obtaining cold stop test results.

[0010] The black body blocking plate is a metal plate for blocking the light exit aperture of the black body to reduce the aperture of the black body output target.

[0011] The two-dimensional linear guide rail is used to drive the black body target to perform two-dimensional scanning in front of the lens, and the movement stroke of the linear guide rail covers the full aperture of the lens.

[0012] The cold light diaphragm two-dimensional adjustment mechanism is used to perform two-dimensional precise adjustment of the cold light diaphragm according to the test results of the cold light diaphragm, and the adjustment precision is better than 0.05 mm.

[0013] Preferably, the black body blocking plate is stably connected with the high-temperature black body, and the high-temperature black body and the black body blocking plate are integrally driven by the two-dimensional linear guide rail to perform two-dimensional full coverage scanning in the full aperture area in front of the main mirror of the detector lens.

[0014] Preferably, the black body blocking plate has a square or circular aperture in the center, and the two sides are kept as metal color without blackening.

[0015] Preferably, the high-temperature black body assembly is driven by the two-dimensional guide rail to realize two-dimensional translation, and the full aperture area of the optical system is scanned by using a serpentine scanning mode.

[0016] Preferably, when the high-temperature black body assembly is located in the aperture of the optical system, the coordinate position (x, y) and the image Image(x, y) at this time are recorded, and the average gray value DN(x, y) of the full field of view is calculated; the high-temperature black body assembly is driven by the two-dimensional guide rail to realize two-dimensional translation, and the full position of the aperture of the optical system is traversed, and the maximum value DN1 of DN(x, y) is calculated; if the average gray value of a certain coordinate position decreases by more than 20% compared with DN1, it is determined that the exit pupil position corresponding to the position has been cut off by the cold light diaphragm.

[0017] Preferably, in the state that the black body is not turned on, the image Image0 is stored, and the average DN value DN0 of the full field of view is calculated as a dark target correction value.

[0018] Preferably, whether the DN values of the edge aperture area are symmetrical is used as a criterion for high-precision test and adjustment of the cold light diaphragm.

[0019] Preferably, whether the DN values of the edge aperture area are symmetrical is used as a criterion for high-precision test and adjustment of the cold light diaphragm, including defining the distance between the (x, y) position and the center of the infrared lens aperture When a certain point (x1, y1) satisfies When the test point (x1, y1) is located at the edge of the infrared lens aperture, and the distance from the edge is within d, the average DN value DN(x1, y1) of the point is called; the symmetric point coordinates (x2, y2) of (x1, y1) relative to the center point (x0, y0) of the aperture are calculated (2x0-x1, 2y0-y1), and the average DN value DN(x2, y2) of the point is called or tested. If DN(x1, y1) < 0.95*DN(x2, y2), it indicates that there is still light cutting at the position of (x1, y1); if DN(x1, y1) > 1.05*DN(x2, y2), it indicates that there is still light cutting at the position of (x2, y2).

[0020] An infrared lens refrigeration type detector cold light shield testing and adjusting method, which uses the testing and adjusting device described above, comprises the following steps:

[0021] S1, starting the detector image acquisition program, and acquiring an image Image0 when there is no infrared target in front;

[0022] S2, stably connecting the blackbody shielding plate and the high-temperature blackbody as a whole, and stably connecting the two-dimensional linear guide rail;

[0023] S3, placing the two-dimensional linear guide rail in front of the infrared lens of the detector close to the camera entrance pupil plane, and moving the plane of the two-dimensional linear mechanism perpendicular to the optical axis Z of the detector, and the blackbody faces the Z direction of the detector, and the two-dimensional linear mechanism drives the blackbody to move as a whole in the XY plane;

[0024] S4, acquiring two-dimensional coordinate values (x, y) and corresponding images Image(x, y) during the movement;

[0025] S5, determining whether the cold light shield at each position causes light cutting by calculating the average DN value of Image(x, y) and comparing different positions with the range of the covered aperture of the detector;

[0026] S6, if the cold light shield causes light cutting, adjusting the position of the cold light shield of the detector using the cold light shield two-dimensional adjusting mechanism, repeating the processes of S1-S5, until no light cutting occurs in the imaging range, thereby realizing the precise adjustment of the cold light shield of the refrigeration type detector.

[0027] Preferably, the adjusting method further comprises:

[0028] Adjusting the position of the refrigeration type detector using the fine adjustment screw of the cold light shield two-dimensional adjusting mechanism until the average gray value DN(x, y) > 0.8DN1 for any point (x, y), and the symmetry of the gray values of each edge aperture meets the requirements, i.e. for any (x1, y1), 0.95*DN(x2, y2) < DN(x1, y1) < 1.05*DN(x2, y2), it is considered that the cold light shield is in a better matching position, and thus the precise adjustment of the cold light shield is completed.

[0029] Wherein (x2, y2) is the coordinate of the symmetric point of (x1, y1) relative to the center point (x0, y0) of the caliber, DN1 is the maximum value of the average value of all pixel gray values.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] (1) The present application can test the matching of the infrared lens exit pupil and the cold light diaphragm, obtain quantitative adjustment direction and data, and guide the precise adjustment of the cold light diaphragm.

[0032] (2) The infrared lens system adopting the present application has weak stray light interference and good imaging effect, and has a short development cycle, which is conducive to improving the signal-to-noise ratio of the refrigeration type infrared lens.

[0033] (3) The present application can change the size and shape of the infrared target by adopting the blackbody blocking piece design, so as to match infrared optical lenses of different sizes and shapes, and realize more accurate cold light diaphragm matching efficiency testing.

[0034] (4) The present application adopts a two-dimensional linear guide rail to drive the blackbody target assembly, so as to realize more accurate and stable position control, and is conducive to quantitative analysis of the exit pupil matching condition.

[0035] (5) The present application adopts a two-dimensional adjustment mechanism to precisely adjust the cold light diaphragm in two dimensions, and the design idea can be applied to different types of infrared lenses, and has high adjustment precision.

[0036] (6) The present application is simple to operate, has clear cold light diaphragm matching efficiency criteria, is compatible with manual operation or full automation, can be used for batch development and production lines of infrared lenses, and has a wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a flow chart of the infrared lens refrigeration type detector cold light diaphragm testing and adjustment method provided by the embodiment of the present application.

[0038] Figure 2 is a two-dimensional guide rail driven high-temperature blackbody assembly traversal path. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0040] An infrared lens refrigeration type detector cold light diaphragm testing and adjustment device comprises a high-temperature blackbody, a blackbody blocking piece, a two-dimensional linear guide rail and a cold light diaphragm two-dimensional adjustment mechanism.

[0041] The high-temperature blackbody is used to provide an infrared target, and the infrared target can be transmitted to the infrared detector through an optical system.

[0042] The blackbody blocking plate is a metal plate for blocking the blackbody light outlet to reduce the aperture of the blackbody output target.

[0043] The two-dimensional linear guide rail is used to drive the blackbody target to scan in two dimensions in front of the lens, and the linear guide rail movement stroke should cover the full aperture of the lens.

[0044] The cold light diaphragm two-dimensional adjustment mechanism is used to adjust the cold light diaphragm in two dimensions according to the test results, and the adjustment accuracy is better than 0.05mm.

[0045] The blackbody blocking plate should be stably connected with the blackbody, and the blackbody and the blocking plate can be driven by the two-dimensional linear guide rail to scan in two dimensions in the full aperture area in front of the main mirror of the lens. The cold light diaphragm two-dimensional adjustment mechanism is used to adjust the cold light diaphragm in two dimensions.

[0046] A cold light diaphragm test and adjustment method based on the infrared lens refrigeration type detector, as shown in Figure 1 The method comprises the following steps:

[0047] S1, erect the measured infrared lens (already installed refrigeration type detector and in the image plane position), start the detector image acquisition program, and acquire the image Image0 when there is no infrared target in front.

[0048] S2, stably connect the blackbody blocking plate and the high-temperature blackbody by screws, adhesives or other methods. Stably connect the high-temperature blackbody and the blackbody blocking plate with the two-dimensional linear guide rail.

[0049] S3, place the two-dimensional linear guide rail in front of the measured infrared lens near the camera entrance pupil plane, and the two-dimensional linear mechanism moving plane is perpendicular to the camera optical axis z direction. The blackbody is directed to the camera Z direction, and the two-dimensional linear mechanism drives the blackbody to move as a whole in the XY plane.

[0050] S4, during the movement, acquire the two-dimensional coordinate values (x, y) and the image Image(x, y) at this time.

[0051] S5, calculate the average DN value of Image(x, y) by analysis, and compare (x, y) with the range of the camera covered aperture to calculate whether the cold light diaphragm occurs light cutting at the (x, y) position.

[0052] S6, according to the cold light diaphragm cutting analysis results, use the cold light diaphragm two-dimensional adjustment mechanism to adjust the whole translation position of the detector cold light diaphragm, repeat the process of S1-S5, until no light cutting occurs in the imaging range, thereby realizing the precise adjustment of the refrigeration type detector cold light diaphragm

[0053] Embodiment:

[0054] The application discloses a kind of infrared lens refrigeration type detector cold light barrier test device and method, utilize the device, and by the overall step flow setting of test adjustment method, the principle of each adjustment step, the requirement that needs to be met etc. are improved, compared with prior art, can effectively solve the high-precision alignment problem of camera exit pupil and cold light barrier position, is driven blackbody assembly by two-dimensional scanning mechanism, scanning is carried out in the XY plane of vertical incident light, the average DN value of refrigeration detector test under different blackbody position state is recorded, the matching condition of cold light barrier and camera exit pupil is obtained, and it is used as the basis to carry out iterative adjustment to cold light barrier, to improve the purpose of infrared camera cold light barrier matching degree.

[0055] The infrared camera to be measured is erected, and a camera coordinate system XYZ is established, wherein the camera optical axis direction is defined as the +Z direction, the vertical direction is the X axis, and the horizontal direction is the Y axis, and the three directions comply with the right-hand rule.The size of the camera optical aperture is measured as D.The refrigeration type detector is installed, and the cold light barrier is built-in in the detector.The refrigeration type detector is used as an imaging component of the infrared camera, and the imaging component in the focal plane assembly should be located at the best focal plane position of the camera.

[0056] The infrared lens used in the embodiment is a coaxial transmission type optical lens, and the main mirror is an entrance pupil light barrier with an aperture of 600 mm.

[0057] Preferably, the +Z direction of the camera remains the horizontal direction of the earth.

[0058] The aperture of the high-temperature blackbody is measured as d, and if d>D / 10, the blackbody light shielding piece needs to be designed, and a square or circular aperture is formed at the center.The blackbody light shielding piece should be made of metal with good thermal conductivity, such as aluminum or steel, and the two sides should be metal color without blackening, so as to limit the aperture of the blackbody and improve the accuracy of the test.The blackbody light shielding piece and the blackbody are stably connected by means of screws to form a high-temperature blackbody assembly.

[0059] Preferably, the light shielding piece is made of aluminum alloy, the aluminum alloy is 7075, the surface is metal color, the thickness is 2 mm, the light shielding piece is circular with a diameter of 50 mm, is placed 5 mm in front of the blackbody heat source, and is connected with the blackbody assembly by means of screws.

[0060] The two-dimensional guide rail is erected, the two translation directions of the two-dimensional guide rail are perpendicular, and the high-temperature blackbody assembly is placed on the two-dimensional guide rail table, so that the light outlet of the high-temperature blackbody is located as close to the main mirror as possible, and the guide rail translation directions are along the X axis and the Y axis of the camera coordinate system respectively.

[0061] Preferably, the two-dimensional guide rail is a ball screw type linear guide rail, and the distance between the blackbody light shielding piece and the main mirror is 20 mm.The stroke of the two-dimensional guide rail in the embodiment is 800 mm.

[0062] Image0, and calculate the average DN value DN0 of the full field of view. In the subsequent test and image acquisition process, the dark target correction is performed based on the image Image0, that is, the acquired image is first subtracted from the corresponding pixel gray value of Image0, and then the data is stored.

[0063] Turn on the high-temperature black body power supply and set the appropriate target temperature. Use the two-dimensional guide rail to drive the high-temperature black body assembly 1 to realize two-dimensional translation within the lens 2 aperture, and use the serpentine scanning method to realize traversal scanning of the full-aperture area of the optical system. The scanning method is as shown in Figure 2 When the high-temperature black body assembly is located within the aperture of the optical system, record the two-dimensional guide rail at the coordinate position (x, y), and store the image Image(x, y). Calculate the average value DN(x, y) of all pixel gray values of Image(x, y). Generally, DN(x, y) should be in the unsaturated state of the detector. Calculate the maximum value DN1 of DN(x, y) as the normalized reference DN value.

[0064] Preferably, the light outlet of the high-temperature black body assembly is located at the center position (x0, y0) of the camera main mirror through the two-dimensional guide rail, and the image Image1 is stored. Calculate the average gray value of the full field of view to obtain DN1.

[0065] Preferably, when performing two-dimensional translation traversal, the (x, y) sampling interval is 0.5d, and when performing serpentine line-by-line scanning, the line spacing is 0.5d.

[0066] Further analyze the full-field average DN value DN(x, y) of the (x, y) position. For example, if the average gray value DN(x, y) at a certain coordinate position (x, y) decreases by more than 20% compared to DN1, it is determined that the corresponding pupil position of the position (x, y) has been cut off by the cold light diaphragm.

[0067] Next, whether the DN value of the edge aperture area is symmetrical is used as the criterion for high-precision test adjustment of the cold light diaphragm. Define the distance between the (x, y) position and the center of the infrared lens aperture as When the distance between a certain point (x1, y1) and the center of the infrared lens aperture is less than 0.5d, it is determined that the cold light diaphragm is not centered. When, it is explained that the test point (x1, y1) is located at the edge of the infrared lens aperture, and the distance from the edge is within d, the DN value average DN(x1, y1) of the point is called. The symmetric point coordinates (x2, y2) of (x1, y1) relative to the center point (x0, y0) of the aperture are calculated (2x0-x1, 2y0-y1), and the DN value average DN(x2, y2) of the point is called or tested. If DN(x1, y1)<0.95*DN(x2, y2), it is explained that the position of (x1, y1) still exists light cutting, and if DN(x1, y1)>1.05*DN(x2, y2), it is explained that the position of (x2, y2) still exists light cutting.

[0068] According to the full-aperture DN value measurement condition described above, the position and area of the lens exit pupil and the cold light diaphragm that do not match are obtained, the direction and translation amount that need to be adjusted of the camera cold light diaphragm are calculated according to the optical model of the camera to be measured. The position of the refrigeration type detector is adjusted by using the fine adjustment screw of the two-dimensional adjustment mechanism of the cold light diaphragm, and the above test process is repeated after adjustment, until the average gray value DN(x, y)>0.8DN1 for any point (x, y), and the gray value symmetry of each edge aperture meets the requirements, that is, for any (x1, y1), 0.95*DN(x2, y2)<DN(x1, y1)<1.05*DN(x2, y2), it is considered that the cold light diaphragm is in a better matching position, and thus the precise assembly and adjustment of the cold light diaphragm are completed.

[0069] The contents not described in detail in the specification of the present application are the known technology of those skilled in the art.

[0070] 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 test and adjustment device for a cooled aperture of an infrared lens detector, characterized in that, This includes a high-temperature blackbody, a blackbody blocking plate, a two-dimensional linear guide, and a two-dimensional adjustment mechanism for a cold aperture; The high-temperature blackbody is used to simulate an infrared target. The infrared target transmits energy to the infrared detector through an optical system. The detector has a built-in cold aperture to continuously acquire the cold aperture test results. The blackbody blocking plate is a metal plate used to block the light output aperture of the blackbody in order to reduce the aperture of the blackbody output target. The two-dimensional linear guide rail is used to drive the blackbody target to perform two-dimensional scanning in front of the lens, and the linear guide rail's movement stroke covers the entire aperture of the lens. The two-dimensional adjustment mechanism for the cold aperture is used to perform two-dimensional precision adjustment of the cold aperture based on the test results, with an adjustment accuracy better than 0.05mm. When the high-temperature blackbody component is located within the aperture of the optical system, its coordinate position (x,y) and the image Image(x,y) at this time are recorded, and the average gray value DN(x,y) of the entire field of view is calculated. The high-temperature blackbody component is translated in two dimensions by driving it through a two-dimensional linear guide, traversing all positions of the optical system aperture, and the maximum value of DN(x,y) is calculated to be DN1. If the average gray value of a certain coordinate position decreases by more than 20% compared with DN1, it is determined that the exit pupil position corresponding to that position has been cut off by the cold aperture. The symmetry of the DN value in the edge aperture region is used as a criterion for high-precision testing and adjustment of the cold aperture, including defining the distance between the (x,y) position and the center of the infrared lens aperture. When a point (x1, y1) satisfies When the test point (x1, y1) is located at the edge of the infrared lens aperture and the distance from the edge is within d, the average DN value of the point is called, DN(x1, y1), where D is the size of the camera optical aperture and d is the aperture of the high-temperature blackbody. The coordinates of the symmetrical point (x2, y2) of (x1, y1) relative to the aperture center point (x0, y0) are calculated as (2x0-x1, 2y0-y1). The average DN value of the point is called or tested, DN(x2, y2). If DN(x1, y1) < 0.95 * DN(x2, y2), it means that there is still tangential light at the position (x1, y1). If DN(x1, y1) > 1.05 * DN(x2, y2), it means that there is still tangential light at the position (x2, y2).

2. The test assembly and adjustment device according to claim 1, characterized in that, The blackbody blocking plate is stably connected to the high-temperature blackbody. The high-temperature blackbody and the blackbody blocking plate are driven by a two-dimensional linear guide rail to perform a two-dimensional full-coverage scan in the full aperture area in front of the detector lens main mirror.

3. The test assembly and adjustment device according to claim 1, characterized in that, The blackbody blocking plate has a square or circular aperture in the center, while the two sides remain metallic and do not turn black.

4. The test assembly and adjustment device according to claim 1, characterized in that, Two-dimensional translation is achieved by driving a high-temperature blackbody component with a two-dimensional linear guide, and a serpentine scanning method is used to traverse the entire aperture area of ​​the optical system.

5. The test assembly and adjustment device according to claim 1, characterized in that, With the blackbody off, save the image Image0 and calculate the average DN value DN0 across the entire field of view as the dark target correction value.

6. A method for testing and adjusting the cold aperture of a cooled infrared lens detector, characterized in that, The test assembly apparatus according to any one of claims 1 to 5 comprises: S1. Start the detector image acquisition program and acquire image Image0 when there is no infrared target in front; S2. After the blackbody shielding plate is securely connected to the high-temperature blackbody, it is used as a whole and then securely connected to the two-dimensional linear guide rail. S3. The two-dimensional linear guide is placed in front of the infrared lens of the detector under test, close to the entrance pupil plane of the camera. The moving plane of the two-dimensional linear guide is perpendicular to the Z-axis of the detector optical axis. The blackbody is facing the Z-direction of the detector. The two-dimensional linear guide drives the blackbody to move as a whole in the XY plane. S4. During the movement, collect the two-dimensional coordinate values ​​(x,y) and the corresponding image Image(x,y); S5. By calculating the average DN value of Image(x,y) and comparing it with the range of detector coverage at different locations, determine whether the cold aperture is cut off at each location; S6. If light cutting occurs in the cold aperture, use the two-dimensional adjustment mechanism of the cold aperture to adjust the overall translation position of the cold aperture of the detector, and repeat the process of S1 to S5 until there is no light cutting in the imaging range, thereby realizing the precise assembly and adjustment of the cold aperture of the cooled detector.

7. The assembly and adjustment method according to claim 6, characterized in that, include: Use the fine-tuning screw of the cold stop two-dimensional adjustment mechanism to adjust the position of the cold stop until, for any point (x, y), the average gray value DN(x, y) > 0.8DN1, and the symmetry of the gray values of each edge aperture meets the requirements, that is, for any (x1, y1), 0.95 * DN(x2, y2) < DN(x1, y1) < 1.05 * DN(x2, y2). Then it is considered that the cold stop is in a better matching position, and the precise alignment of the cold stop is completed至此完成冷光阑的精密装调; where (x2, y2) is the symmetric point coordinates of (x1, y1) relative to the center point (x0, y0) of the aperture, and DN1 is the maximum value of the average of all pixel gray values.

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