A low-temperature background test method for resistance array radiation characteristics

Abstract

A low-temperature background test method for the radiation characteristics of a resistor array is applied to a resistor array radiation characteristics test device. The test device can image the intermediate image of the image-side cold stop onto the object-side cold stop, so that the image-side cold stop truly blocks the ambient thermal radiation between the resistor array and the infrared detector, preventing the thermal radiation from being sensitive to the infrared detector and generating thermal noise. Because the object-side cold stop blocks the thermal radiation beam generated by hot components outside the image-side cold stop, it can prevent the thermal radiation beam from being reflected by the surface of the resistor array and forming a non-uniform cold reflection image on the infrared detector. The test method of the present invention eliminates the negative effects of thermal noise, cold reflection, and equivalent blackbody radiation temperature on radiation characteristics testing, achieves accurate testing of the MOS resistor array target simulator, and thus provides an important reference basis for the infrared scene image generated by the MOS resistor array target simulator.

Description

Technical Field

[0001] The present invention relates to the field of thermal imaging technology, and in particular to a low-temperature background testing method for radiation characteristics of a resistor array. Background Art

[0002] MOS resistor arrays, due to their ability to convert digital images into infrared images, are widely used in hardware-in-the-loop simulations of infrared-guided weapons, simulating complex optoelectronic countermeasure target environments. Currently, due to the unique internal structure of MOS resistor arrays, their surfaces exhibit mirror-like reflectivity with an effective reflectivity exceeding 80%.

[0003] like Figure 1-2 As shown, the lens of a conventional thermal imager 100 is a primary imaging optical system. To block thermal noise generated by the environment surrounding the infrared detector 102, an image-side cold stop 104 is positioned within the dewar flask 101, in front of the infrared detector 102. The image formed by the image-side cold stop 104 in the object space through the lens is called the entrance pupil. Because the image-side cold stop 104 is located between the infrared detector 102 and the lens, the intermediate image 401 of the image-side cold stop is formed behind the infrared detector 102, failing to block the ambient thermal radiation between the resistor array 301 and the infrared detector 102. Background ambient thermal radiation can reach temperatures of 10-30°C, which is sensitive to the infrared detector 102 and generates thermal noise. On the other hand, the beam formed by the image-side cold stop 104 in the object space is reflected by a mirror surface (such as the surface of a MOS resistor array) and then re-imaged by the lens near the infrared detector 102. This phenomenon, which makes the infrared detector 102 sensitive, is known as the cold reflection phenomenon in infrared detection systems. Because the image-side cold stop's temperature (-196°C) is lower than its surroundings, and the cold reflection image doesn't overlap with the infrared detector, the cold reflection image appears as a black speckled pattern with blurred edges, causing non-uniformity in the test image. The combination of these two conditions results in significant deviations in the test results, seriously affecting the accuracy of the resistor array's radiation characteristics test.

[0004] Furthermore, although the resistor array substrate is cooled to 0°C during testing, its equivalent blackbody temperature remains below 0°C. Furthermore, the test results of existing thermal imagers are affected by ambient temperature fluctuations, with their equivalent blackbody radiation temperature fluctuating between 20°C and 30°C and remaining uncertain. This also negatively impacts the resistance array's radiation characteristics.

[0005] The above problems have always plagued the testing of the radiation characteristics of resistor arrays and the testing of low-temperature background. Up to now, there has been no research literature on the testing of low-temperature background and radiation characteristics of resistor arrays. Summary of the Invention

[0006] In order to overcome the shortcomings of the background technology, the present invention discloses a low-temperature background test method for the radiation characteristics of a resistor array, the purpose of which is to eliminate the thermal noise and cold reflection phenomenon generated by the cold aperture, and avoid the negative impact of the equivalent blackbody radiation temperature on the radiation characteristics test.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] A low-temperature background test method for the radiation characteristics of a resistor array is applied to a resistor array radiation characteristics test device. The resistor array radiation characteristics test device includes a thermal imager body, a test lens, a resistor array, and a blackbody. The test lens is mounted on the thermal imager body, which has an infrared detector and an image-side cold stop. The test lens consists of a front imaging lens group, a rear imaging lens group, and a lens barrel. An object-side cold stop is provided between the test lens and the resistor array. The thermal imager body and the test lens are mounted on a rotating stage, and the blackbody is arranged in a fan-shaped array with the axis of the rotating stage as the center.

[0009] The test method comprises the following steps:

[0010] S1: Adjust the front imaging lens group and the rear imaging lens group so that the thermal image of the resistor array is imaged on the infrared detector array surface, and the image-side cold stop is imaged on the object-side cold stop;

[0011] S2: Adjust the position of the object side cold stop forward and backward so that the image of the object side cold stop coincides with the image of the image side cold stop, thereby blocking the thermal radiation beam outside the imaging optical path and preventing the thermal radiation beam from entering the surface of the resistor array and forming a non-uniform cold reflection image on the infrared detector;

[0012] S3: Use a radiation thermometer and a blackbody to calibrate the resistance array radiation characteristic test device;

[0013] S4: Test the radiation characteristics of the resistor array to obtain the background equivalent blackbody temperature of the resistor array.

[0014] To further improve the technical solution, the object-side cold aperture and the resistor array are installed in a vacuum environment chamber, and a spherical window plate is installed at the end of the vacuum environment chamber facing the test lens. The spherical window plate is used to diffuse and reflect the thermal radiation scattered light generated by the resistor array that fails to pass through the spherical window plate to the surrounding areas, thereby preventing the thermal radiation scattered light from being reflected by the surface of the resistor array and forming background thermal radiation.

[0015] To further improve the technical solution, the object side cold aperture stop is in a sleeve shape, and the resistor array is located in the inner hole of the object side cold aperture stop.

[0016] To further improve the technical solution, S3 includes the following sub-steps:

[0017] S3.1: Calibrate the equivalent temperature of the blackbody outlet;

[0018] Mount the radiation thermometer on the axis of the rotating stage, electrically heat the blackbody, and set the heating temperature of the blackbody; set the radiation thermometer's emissivity to 1.0, and adjust the distance between the blackbody and the radiation thermometer so that the radiation thermometer's visible light indicator system focuses on the blackbody's exit. Wait until the blackbody temperature stabilizes before testing; rotate the radiation thermometer so that it is aimed at the next blackbody, and test blackbodies of different temperatures one by one;

[0019] S3.2: Calibrate thermal imager;

[0020] Mount the thermal imager and the test lens on the axis of the rotating stage, electrically heat the black body, and set the heating temperature of the black body; start the thermal imager, set the integration time, and perform non-uniformity correction on the thermal imager; adjust the position of the black body relative to the thermal imager and the test lens so that the image of the black body's exit aperture on the infrared detector surface is clear and the grayscale value of the image output by the thermal imager is between 55% and 85% of its range to reduce instrument error and the impact on test stability. Otherwise, reset the integration time;

[0021] S3.2: Build and debug the test optical path;

[0022] Draw a 72×72 element test range frame in the center of the display of the thermal imager body, light up the 216×216 element resistor array, and adjust the relative position between the resistor array and the test lens so that the thermal image of the resistor array on the surface of the infrared detector is clear and the thermal image fills the test range frame of the display, realizing object-image conjugation.

[0023] Due to the adoption of the above technical solution, compared with the background technology, the present invention has the following beneficial effects:

[0024] The present invention provides a device for testing the radiation characteristics of a resistor array. This device can project the intermediate image of an image-side cold stop onto an object-side cold stop, effectively shielding the ambient thermal radiation between the resistor array and the infrared detector, preventing the infrared detector from being sensitive to this radiation and generating thermal noise. Furthermore, the object-side cold stop blocks the thermal radiation beam generated by hot components outside the image-side cold stop, preventing this radiation beam from being reflected by the resistor array surface and forming a non-uniform cold reflection image on the infrared detector.

[0025] The present invention also provides a method for testing the radiation characteristics of a resistor array under a low-temperature background, which realizes accurate testing of a MOS resistor array target simulator, thereby providing an important reference basis for the infrared scene image generated by the MOS resistor array target simulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is a schematic diagram of the structure of an existing resistance array radiation characteristic testing device.

[0027] Figure 2 for Figure 1 Light path diagram.

[0028] Figure 3 This is a schematic diagram of the structure of the thermal imager body, test lens and vacuum environment chamber.

[0029] Figure 4 This is a structural diagram of the resistance array radiation characteristics testing device.

[0030] Figure 5 for Figure 3 Light path diagram.

[0031] Figure 6 This is the light path diagram of the spherical window plate.

[0032] Figure 7 Schematic diagram of calibrating the equivalent temperature of a blackbody outlet using a radiation thermometer.

[0033] Figure 8 Schematic diagram of calibrating the blackbody outlet equivalent temperature using the thermal imager body and test lens.

[0034] Figure 9 This is an image of the resistor array output.

[0035] Figure 10 This is the image displayed by the infrared detector.

[0036] Figure 11 It is a curve graph of thermal image grayscale and temperature.

[0037] In the figure: 100, thermal imager body; 101, Dewar flask; 102, infrared detector; 103, filter; 104, image-side cold stop; 105, filter wheel; 200, test lens; 201, lens barrel; 202, rear imaging lens group; 203, front imaging lens group; 204, infrared band filter; 300, vacuum environment chamber; 301, resistor array; 302, substrate plate; 303, refrigerator; 304, object-side cold stop; 305, spherical window plate; 401, intermediate image of image-side cold stop; 402, thermal imaging of resistor array; 403, intermediate image of resistor array; 500, blackbody; 600, rotation stage; 700, two-dimensional translation stage; 800, radiation thermometer. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. It should be noted that in the description of the present invention, the terms "front", "rear", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation of the present invention. It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a communication between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0039] A method for testing the radiation characteristics of a resistor array under low-temperature background conditions requires a resistor array radiation characteristics testing device. The device includes a thermal imager, a test lens, a resistor array, and a blackbody. The following describes its structure and function.

[0040] like Figure 3 As shown, the thermal imager body has a dewar flask and a cooling system. An infrared detector 102, a filter 103 and an image-side cold stop 104 are sequentially arranged inside the dewar flask 101, and a filter wheel 105 is arranged in front of the window plate of the dewar flask 101.

[0041] The test lens 200 is connected to the front end of the thermal imager body 100. Unlike the single-group imaging lens included with existing thermal imagers, the test lens 200 includes a front imaging lens group 203 and a rear imaging lens group 202 within its lens barrel 201. The front imaging lens group 203 and the rear imaging lens group 202 can move forward and backward to adjust the image of the resistor array 301 on the infrared detector 102. To enhance the infrared filtering effect, an infrared filter 204 is installed at the front end of the lens barrel 201.

[0042] A vacuum chamber 300 is located in front of the test lens 200. A spherical window plate 305 is mounted on the end of the chamber 300 facing the lens barrel 201. Inside the chamber 300 are an object-side cold stop 304, a resistor array 301, a substrate plate 302, and a refrigerator 303. The resistor array 301 is square and mounted on the substrate plate 302, with the object-side cold stop 304 positioned between the test lens 200 and the resistor array 301. The object-side cold stop 304 is roughly sleeve-shaped, with an outwardly extending disk and a square inner hole. The object-side cold stop 304 nestles the resistor array 301 within its square inner hole. The back of the substrate plate 302 is in close contact with the refrigerator 303, which cools the resistor array 301 through the substrate plate 302.

[0043] like Figure 4 As shown, the thermal imager body 100 and the test lens 200 are mounted on a rotating stage 600, and the vacuum environmental chamber 300 is installed opposite the test lens 200. To facilitate adjustment of the distance between the vacuum environmental chamber 300 and the test lens 200 and to align the resistor array 301 with the test lens 200, the vacuum environmental chamber 300 is mounted on a two-dimensional translation stage 700. A two-dimensional translation stage 700 is also installed between the thermal imager body 100 and the rotating stage 600. Multiple black bodies 500 are arranged around the rotating stage 600 in a fan-shaped array, centered about the axis of the rotating stage 600.

[0044] This test method includes the following steps:

[0045] S1: Adjust the front imaging lens group 203 and the rear imaging lens group 202 so that the thermal image of the resistor array 301 is imaged on the array surface of the infrared detector 102, and the image-side cold stop 104 is imaged on the object-side cold stop 304.

[0046] like Figure 5 As shown, the redesigned front imaging lens group 203 and rear imaging lens group 202 can form an intermediate image 403 of the resistor array between the front imaging lens group 203 and the rear imaging lens group 202, and can also form a thermal image 402 of the resistor array onto the infrared detector 102. More importantly, the front imaging lens group 203 and the rear imaging lens group 202 can also form an intermediate image 401 of the image-side cold stop onto the object-side cold stop 304, allowing the image-side cold stop 104 to effectively block the ambient thermal radiation between the resistor array 301 and the infrared detector 102, preventing the thermal radiation from being sensitive to the infrared detector 102 and generating thermal noise.

[0047] S2: Adjust the position of the object side cold stop 304 forward and backward so that the image of the object side cold stop 304 and the image side cold stop 104 overlap. Figure 5It can be seen that the object-side cold stop 304 blocks the thermal radiation beam generated by the thermal components outside the image-side cold stop 104 , preventing the thermal radiation beam from entering the surface of the resistor array 301 and forming a non-uniform cold reflection image on the infrared detector 102 .

[0048] like Figure 6 As shown, unlike the flat window plate in the existing vacuum environment chamber 300, the spherical window plate 305 has a larger reflection angle. This diffuses and reflects the scattered thermal radiation generated by the resistor array 301 that fails to pass through the spherical window plate 305, preventing it from mixing into the imaging beam. This prevents the scattered thermal radiation from being reflected by the surface of the resistor array 301 and forming background scattered thermal radiation. This measure can obviously reduce the background thermal noise of the imaging system and improve the signal-to-noise ratio of the image.

[0049] S3: Use the radiation thermometer 800 and the blackbody 500 to calibrate the radiation characteristic test device of the resistor array 301.

[0050] S3.1: Calibrate the equivalent temperature of the blackbody 500 outlet

[0051] like Figure 7 As shown, the radiation thermometer 800 is mounted on the axis of the rotating table 600, the black body 500 is electrically heated, and the heating temperature of the black body 500 is set; then the emissivity of the radiation thermometer 800 is set to 1.0, and the distance between the black body 500 and the radiation thermometer 800 is adjusted so that the visible light indication system of the radiation thermometer 800 is focused on the exit of the black body 500, and the test is performed after the temperature of the black body 500 stabilizes; the radiation thermometer 800 is rotated so that the radiation thermometer 800 is aligned with the next black body 500, and the black bodies 500 of different temperatures are tested one by one.

[0052] S3.2: Calibrate the thermal imager

[0053] like Figure 8 As shown, the thermal imager body 100 and the test lens 200 are mounted on the axis of the rotating stage 600. The black body 500 is electrically heated and its heating temperature is set. The thermal imager body 100 is started, the integration time is set, and non-uniformity correction is performed on the thermal imager body 100. The position of the black body 500 relative to the thermal imager body 100 and the test lens 200 is then adjusted so that the image of the black body 500's exit aperture on the surface of the infrared detector 102 is clear and the grayscale value of the image output by the thermal imager body 100 is between 55% and 85% of its range to reduce instrument error and the impact on test stability. Otherwise, the integration time is reset. If black spots similar to blind pixels appear in the thermal image, the black body 500's aperture size is reduced until the black spots disappear. The calibration test frame is also reduced accordingly so that the test range is smaller than the thermal image of the black body 500's exit aperture.

[0054] S3.2: Build and debug the test optical path

[0055] In this embodiment, a 72×72 element test range frame is drawn in the center of the display of the thermal imager body 100, the 216×216 element resistor array 301 is lit, and the relative position between the resistor array 301 and the test lens 200 is adjusted so that the thermal image of the resistor array 301 on the surface of the infrared detector 102 is clear and the thermal image fills the test range frame of the display, thereby achieving object-image conjugation.

[0056] S4: Testing the radiation characteristics of the resistor array 301 to obtain the background equivalent blackbody 500 temperature of the resistor array 301. In this embodiment, the radiation characteristics of the resistor array 301 are tested within the 4.4-4.8 μm band.

[0057] First, set the control voltage (or grayscale) of the resistor array 301 and the thermal imager integration time to correct the non-uniformity of the test system. The grayscale of the resistor array 301 image should be between 55% and 85% of the range. Otherwise, reset the thermal imager integration time to make the image grayscale meet this requirement. Then, set the frame rate of the thermal imager body 100 and the resistor array 301 to 100Hz. After the resistor array 301 is driven to zero, it is re-driven at the set voltage. The output image of the resistor array 301 is as follows: Figure 9 After a delay of 1s, the thermal image is recorded for 50 frames. After the recording is completed, the resistor array 301 is cleared. The image displayed by the infrared detector 102 is as follows: Figure 10 Finally, the integration time of the thermal imager and the average grayscale value of the 50 frames are recorded and compared with the calibration results of the test system to obtain the equivalent blackbody 500 temperature value of the thermal image.

[0058] The thermal image grayscale and temperature curve is as follows Figure 11 Table 1 is the correspondence table between image grayscale value and temperature. In Table 1, serial numbers 1-17 correspond to image grayscale values 0 to 256. Figure 11 As shown in Table 1, when the grayscale value ranges from 0 to 96, the average equivalent blackbody temperature of the image is less than 0°C, the temperature changes slowly, and the image standard deviation is less than 0.37. When the grayscale value exceeds 96, the equivalent blackbody temperature of the thermal image changes significantly, showing an exponential trend. When the grayscale value increases to 256, the equivalent blackbody temperature of the thermal image rises to 200.81°C.

[0059] Table 1

[0060]

[0061]

[0062] From the above, it can be seen that this test method realizes the accurate test of the MOS resistor array target simulator, thereby providing an important reference basis for the infrared scene image generated by the MOS resistor array target simulator.

[0063] Parts not described in detail are prior art. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for testing the radiation characteristics of a resistor array at a low temperature background, characterized by: The invention is applied to a resistor array radiation characteristics test device, comprising a thermal imager body, a test lens, a resistor array, and a blackbody. The test lens is mounted on the thermal imager body, which has an infrared detector and an image-side cold stop. The test lens is composed of a front imaging lens group, a rear imaging lens group, and a lens barrel. An object-side cold stop is provided between the test lens and the resistor array. The thermal imager body and the test lens are mounted on a rotating stage, and the blackbody is arranged in a fan-shaped array with the axis of the rotating stage as the center. The test method comprises the following steps: S1: Adjust the front imaging lens group and the rear imaging lens group so that the thermal image of the resistor array is imaged on the infrared detector array surface, and the image-side cold stop is imaged on the object-side cold stop; S2: Adjust the position of the object side cold stop forward and backward so that the image of the object side cold stop coincides with the image of the image side cold stop, thereby blocking the thermal radiation beam outside the imaging optical path and preventing the thermal radiation beam from entering the surface of the resistor array and forming a non-uniform cold reflection image on the infrared detector; S3: Use a radiation thermometer and a blackbody to calibrate the resistance array radiation characteristic test device; S4: Test the radiation characteristics of the resistor array to obtain the background equivalent blackbody temperature of the resistor array.

2. The method for testing the radiation characteristics of a resistor array at a low temperature background as claimed in claim 1, wherein: The object-side cold aperture and resistor array are installed in a vacuum environment chamber. A spherical window plate is installed at the end of the vacuum environment chamber facing the test lens. The spherical window plate is used to diffuse and reflect the thermal radiation scattered light generated by the resistor array that fails to pass through the spherical window plate to the surrounding area, preventing the thermal radiation scattered light from being reflected by the surface of the resistor array and forming background thermal radiation.

3. A method for testing radiation characteristics of a resistor array at low temperature background using the test device according to claim 1 or 2, characterized in that: The object side cold aperture stop is in a sleeve shape, and the resistor array is located in the inner hole of the object side cold aperture stop.

4. The method for testing the radiation characteristics of a resistor array at a low temperature background as claimed in claim 1, wherein: S3 includes the following sub-steps: S3.1: Calibrate the equivalent temperature of the blackbody outlet; Mount the radiation thermometer on the axis of the rotating stage, electrically heat the blackbody, and set the heating temperature of the blackbody; set the radiation thermometer's emissivity to 1.0, and adjust the distance between the blackbody and the radiation thermometer so that the radiation thermometer's visible light indicator system focuses on the blackbody's exit. Wait until the blackbody temperature stabilizes before testing; rotate the radiation thermometer so that it is aimed at the next blackbody, and test blackbodies of different temperatures one by one; S3.2: Calibrate thermal imager; Mount the thermal imager and the test lens on the axis of the rotating stage, electrically heat the black body, and set the heating temperature of the black body; start the thermal imager, set the integration time, and perform non-uniformity correction on the thermal imager; adjust the position of the black body relative to the thermal imager and the test lens so that the image of the black body's exit aperture on the infrared detector surface is clear and the grayscale value of the image output by the thermal imager is between 55% and 85% of its range to reduce instrument error and the impact on measurement stability. Otherwise, reset the integration time; S3.2: Build and debug the test optical path; Draw a 72×72 element test range frame in the center of the display of the thermal imager body, light up the 216×216 element resistor array, and adjust the relative position between the resistor array and the test lens so that the thermal image of the resistor array on the surface of the infrared detector is clear and the thermal image fills the test range frame of the display, realizing object-image conjugation.

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