Movable comprehensive maintenance and test equipment for small thermal imager

Abstract

The invention discloses a movable small thermal imager comprehensive maintenance and test device, and relates to the field of thermal imager maintenance and test. The invention relates to a movable comprehensive maintenance and test device for a small thermal imager, which is characterized in that the maintenance and test device comprises an optical machine supporting platform, a reflective collimation optical system, a variable temperature difference target generator and an industrial personal computer, and the variable temperature difference target generator comprises a target, a surface source black body and a black body controller. The reflection type collimation optical system, the target and the surface source black body are installed in the optical machine supporting platform. The black body controller is connected with the surface source black body and the industrial personal computer through cables. The frame-type lightweight design is adopted, the structural design adopts a frame-type structure constructed after light profiles are subjected to finish machining, and the design precision requirement is considered while the lightweight requirement and the bearing strength are met; the testing requirements of various common thermal image performance parameters such as zero position walking testing and optical axis consistency testing can be met, and the functions are comprehensive.

Description

Technical Field

[0001] This invention patent relates to the field of thermal imager repair and testing, and in particular to a portable small-sized comprehensive thermal imager repair and testing device with a frame structure that is lightweight and compact. Background Technology

[0002] Currently, most of the equipment used for the assembly, adjustment, testing, and repair of thermal imagers, both domestically and internationally, are large-scale integrated testing systems designed for laboratory conditions. These systems offer excellent performance and comprehensive functions, but are bulky, have high environmental requirements, and are only suitable for assembly, adjustment, testing, and base-level repair under laboratory conditions. With the continuous development and expansion of the demand for thermal imager repair and testing, some on-site testing, evaluation, and repair equipment for already installed thermal imager products has emerged in recent years. This type of equipment is smaller, lighter, and easier to move and transport; however, individual units have limited functionality and insufficient ability to identify and resolve problems on-site. Summary of the Invention

[0003] The present invention aims to solve the problem that current thermal imager testing and repair equipment cannot simultaneously achieve both size and functionality, and provides a portable small-scale comprehensive thermal imager repair and testing equipment with a frame structure that is lightweight and compact.

[0004] The portable miniature thermal imager integrated maintenance and testing equipment of the present invention is characterized in that the maintenance and testing equipment includes an optomechanical support platform, a reflective collimating optical system, a variable temperature difference target generator, and an industrial control computer. The variable temperature difference target generator includes a target, a blackbody, and a blackbody controller. The reflective collimating optical system, the target, and the blackbody are installed inside the optomechanical support platform. The blackbody controller is connected to the blackbody and the industrial control computer via cables.

[0005] The optomechanical support platform includes a front window cover, a front upright plate, foot pads, a right side plate, handles, side beams, a base plate, upright beams, a target support frame, a target locking block, a rear upright plate, a pressure ring, crossbeams, side plates, a target replacement window, and a top cover plate. There are four side beams, arranged parallel to each other on the upper and lower left and right sides of the optomechanical support platform. Two upright beams are vertically installed on the left and right sides of the platform, respectively, with their ends fixedly connected to the side beams arranged on the same side. Two crossbeams are horizontally installed on the upper and lower parts of the platform, respectively, with their ends connected to the upper or lower parts of the platform. The side beams are fixedly connected; the front and rear uprights are respectively installed at the front and rear ends of the optical engine support platform; the front window cover is set on the front upright, the target support frame and the target locking block are both installed on the rear upright, and the rear upright is also provided with a primary mirror mounting hole, and a pressure ring is installed in the primary mirror mounting hole; the bottom of the lower crossbeam is also provided with a foot pad; the right side plate, bottom plate, left side plate and top cover plate are fixed to the side beam, crossbeam and upright beam by screws; the target replacement window is installed on the right side plate and the rear upright by hinges and spring screws; handles are respectively installed on the left side plate and the right side plate;

[0006] The reflective collimating optical system includes a primary mirror, an aperture diaphragm support, an aperture diaphragm, a secondary mirror, and a six-dimensional adjustment mechanism. The primary mirror is mounted on the rear panel and is vibration-isolated and fixed to the rear panel by optical adhesive and a pressure ring. The secondary mirror is mounted on the front panel via the six-dimensional adjustment mechanism. The aperture diaphragm is mounted on the side beam on the lower right side via an aperture diaphragm support.

[0007] The variable temperature difference target generator includes a surface source blackbody, a target, and a blackbody controller. The surface source blackbody is mounted on the rear upright plate. The target is inserted into the target support frame and fixed by the target clamping block. The blackbody controller is connected to the power supply, industrial control computer, and surface source blackbody via a cable.

[0008] The industrial control computer is equipped with thermal imager comprehensive performance testing software, which is connected to the blackbody controller via a cable.

[0009] After receiving control commands from the industrial control computer via a blackbody controller, this device controls the surface blackbody to generate infrared radiation at a specific temperature. The infrared radiation passes through a target to generate different infrared radiation targets. The infrared radiation targets are located on the optical focal plane of the reflective collimating optical system. After two reflections by the reflective collimating optical system, a clear and unobstructed collimated beam with a target at near infinity can be provided for various debugging and testing of the infrared thermal imager. The industrial control computer adjusts the external radiation temperature of the surface blackbody via the blackbody controller. Different test software is installed in the industrial control computer to calculate various performance parameters of the thermal imager in real time.

[0010] This invention relates to a portable, small-sized thermal imager integrated maintenance and testing equipment. It features a frame-type, lightweight design, constructed from precision-machined lightweight profiles, supported by adjustable crossbeams and vertical beams. This design satisfies both lightweight requirements and structural strength while maintaining design accuracy. It boasts a high degree of integration, small size, and efficient space utilization. The reflective collimating optical system incorporates a six-dimensional adjustment mechanism for quick and convenient assembly and adjustment. With an effective aperture of φ180mm and a focal length of 2000mm, the system is applicable to virtually all second-generation thermal imager products, offering a wide range of applications. By replacing different infrared targets and using appropriate testing software, it can meet various common thermal imaging performance parameter testing needs, such as zero-position movement testing and optical axis consistency testing, providing comprehensive functionality. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the composition and layout of the maintenance and testing equipment of the present invention.

[0012] Figure 2 This is a schematic diagram of the composition and layout of the optomechanical support platform of the present invention.

[0013] Figure 3 This is a schematic diagram of the composition and layout of the reflective collimating optical system of the present invention.

[0014] Figure 4 This is a schematic diagram of the composition and layout of the variable temperature difference target generator of the present invention.

[0015] Figure 5 The figure shows the experimental results of SiTF / NETD measurement using a thermal imager for this invention.

[0016] Figure 6 The figure shows the experimental results of MRTD measurement using a thermal imager for this invention.

[0017] Figure 7 The figure shows the experimental results of MTF measurement using a thermal imager in this invention.

[0018] Figure 8 The figure shows the experimental results of measuring the optical axis consistency of the thermal imager for this invention.

[0019] The components include: 1. Optomechanical support platform; 2. Reflective collimating optical system; 3. Variable temperature difference target generator; 4. Industrial control computer; 5. Front window cover; 6. Front upright plate; 7. Foot pad; 8. Right side plate; 9. Handle; 10. Upper right and lower right side beams; 11. Base plate; 12. Left and right upright beams; 13. Target support frame; 14. Target locking block; 15. Rear upright plate; 16. Pressure ring; 17. Upper and lower crossbeams; 18. Upper left and lower left side beams; 19. Left side plate; 20. Target replacement window; 21. Top cover plate; 22. Primary reflector; 23. Aperture bracket; 24. Aperture; 25. Secondary reflector; 26. Six-dimensional adjustment mechanism; 27. Surface source blackbody; 28. Target; and 29. Blackbody controller. Detailed Implementation

[0020] Example 1: A portable, small-scale thermal imager integrated maintenance and testing device, comprising an optomechanical support platform, a reflective collimating optical system, a variable temperature difference target generator, and an industrial control computer. The variable temperature difference target generator includes a target, a blackbody, and a blackbody controller. The reflective collimating optical system, the target, and the blackbody are installed within the optomechanical support platform. The blackbody controller is connected to the blackbody and the industrial control computer via cables.

[0021] The optomechanical support platform includes a front window cover, a front upright plate, foot pads, a right side plate, handles, side beams, a base plate, upright beams, a target support frame, a target locking block, a rear upright plate, a pressure ring, crossbeams, side plates, a target replacement window, and a top cover plate. There are four side beams, arranged parallel to each other on the upper and lower left and right sides of the optomechanical support platform. Two upright beams are vertically installed on the left and right sides of the platform, respectively, with their ends fixedly connected to the side beams arranged on the same side. Two crossbeams are horizontally installed on the upper and lower parts of the platform, respectively, with their ends connected to the upper or lower parts of the platform. The side beams are fixedly connected; the front and rear uprights are respectively installed at the front and rear ends of the optical engine support platform; the front window cover is set on the front upright, the target support frame and the target locking block are both installed on the rear upright, and the rear upright is also provided with a primary mirror mounting hole, and a pressure ring is installed in the primary mirror mounting hole; the bottom of the lower crossbeam is also provided with a foot pad; the right side plate, bottom plate, left side plate and top cover plate are fixed to the side beam, crossbeam and upright beam by screws; the target replacement window is installed on the right side plate and the rear upright by hinges and spring screws; handles are respectively installed on the left side plate and the right side plate;

[0022] The reflective collimating optical system includes a primary mirror, an aperture diaphragm support, an aperture diaphragm, a secondary mirror, and a six-dimensional adjustment mechanism. The primary mirror is mounted on the rear panel and is vibration-isolated and fixed to the rear panel by optical adhesive and a pressure ring. The secondary mirror is mounted on the front panel via the six-dimensional adjustment mechanism. The aperture diaphragm is mounted on the side beam on the lower right side via an aperture diaphragm support.

[0023] The variable temperature difference target generator includes a surface source blackbody, a target, and a blackbody controller. The surface source blackbody is mounted on the rear upright plate. The target is inserted into the target support frame and fixed by the target clamping block. The blackbody controller is connected to the power supply, industrial control computer, and surface source blackbody via a cable.

[0024] The industrial control computer is equipped with comprehensive performance testing software for thermal imagers and control software for variable temperature difference target generators. It is connected to a blackbody controller via a cable. The comprehensive performance testing software for thermal imagers, combined with a dedicated test target, can calculate various performance parameters of the thermal imager in real time, enabling the testing and maintenance of key performance parameters of infrared thermal imagers such as SiTF / NETD, MRTD, MTF, and optical axis consistency.

[0025] The specific testing process is as follows:

[0026] 1) SiTF / NETD Measurement: SiTF tests the response function of a thermal imager, which characterizes the imager's ability to convert input temperature changes into electrical or image signals. During testing, the thermal imager is placed in front of the collimator window, and its video signal is connected to an industrial computer. A suitable semi-circular or circular target is placed in the target holder, ensuring a clear image is centered on the imager's field of view. The maximum temperature difference is then set. and minimum temperature difference The sampling number N and the blackbody target test area are determined, and the measurement begins. The blackbody controller causes the blackbody and the target to form a differential signal. After being reflected by the reflective collimator, a temperature difference signal target is formed at approximately infinity. The test image received by the thermal imager under test, and the signal output received by the acquisition card, are represented as follows:

[0027]

[0028] In the formula, G is the system gain of the thermal imager under test. Let be the response function of the thermal imager under test. To enable the thermal imager to effectively detect the element area, This refers to the optical f-number of the thermal imager. For spectral radiance, The transmittance of the thermal imager under test. To test the transmittance of the system and the test environment, the signals collected during the test are discrete data points. The least squares method is used to fit the data to obtain the SiTF curve, and the slope of the curve is the system responsivity. The calculation formula is:

[0029]

[0030] Fourier transform is performed on the acquired image signals to analyze the noise distribution in the frequency domain and obtain the noise power spectrum (NPS) curve. Multiple frames of images are acquired, and the voltage fluctuation of each pixel over time is calculated. After removing the inter-frame average, the root mean square (RMS) value of the remaining fluctuation is calculated to obtain the root mean square noise (NETD). Based on the SiTF and MRS test results, the NETD is calculated using the following formula:

[0031]

[0032] The noise root mean square (RMS) is represented by SiTF, which is the signal transfer function, and finally converted to mk.

[0033] 2) MRTD Measurement: During testing, the thermal imager is placed on the testing platform, ensuring its optical axis is at the same horizontal level as the main optical axis of the testing equipment. A four-bar target corresponding to the required spatial frequency is selected, and the temperature of the blackbody is controlled to ensure that the positive contrast four-bar target image is clearly distinguishable. At this point, the temperature difference is... ,from Start cooling until the four-bar target image with positive contrast is no longer distinguishable; the temperature difference at this point is the measured positive temperature difference. Adjust the blackbody temperature difference to make the negative contrast four-bar target image clearly distinguishable; at this point, the temperature difference is... ,from Start heating until the negative contrast of the four-bar target image is indistinguishable; the temperature difference at this point is the measured negative temperature difference. The MRTD at the tested spatial frequency point is calculated using the following formula:

[0034]

[0035] Obtain MRTD measurement values;

[0036] 3) MTF measurement: During the test, the thermal imager is placed on the test stage, with its optical axis at the same horizontal level as the main optical axis of the test equipment. A four-bar target or a slit target is selected for testing. The blackbody temperature difference of the test equipment is adjusted. Within the test area, the response values ​​of all rows of pixels in each column are averaged first. Then, the average response value of each pixel in the averaged row is calculated for N frames. The knife-edge response curve is obtained from these average response values. The knife-edge response curve is differentiated, and after Fourier transform and normalization, the MTF curve can be obtained.

[0037] 4) Optical axis consistency measurement: Select a point target or a crosshair target as the test target. Focus the camera clearly within the test reference field of view. Adjust the test stage so that the center of the thermal imager's crosshair reticle coincides with the center of the crosshair target image or the point target image, obtaining the coordinates of the first target point. Switch the thermal imager to another field of view, reselect the target measurement area, and obtain the coordinates of the second target point. Then calculate the deviation value of the thermal imager's optical axis consistency using the following formula:

[0038]

[0039] The azimuth deviation between two measurements of the target coordinates. For pitch deviation;

[0040] The test results of optical axis consistency offset value were obtained.

Claims

1. A portable, small-sized thermal imager integrated maintenance and testing device, characterized in that... The maintenance and testing equipment includes an optomechanical support platform, a reflective collimating optical system, a variable temperature difference target generator, and an industrial control computer. The variable temperature difference target generator includes a target, a blackbody, and a blackbody controller. The reflective collimating optical system, the target, and the blackbody are installed inside the optomechanical support platform. The blackbody controller is connected to the blackbody and the industrial control computer via cables. The optomechanical support platform includes a front window cover, a front upright plate, foot pads, a right side plate, handles, side beams, a base plate, upright beams, a target support frame, a target locking block, a rear upright plate, a pressure ring, crossbeams, side plates, a target replacement window, and a top cover plate. There are four side beams, arranged parallel to each other on the upper and lower left and right sides of the optomechanical support platform. Two upright beams are vertically installed on the left and right sides of the platform, respectively, with their ends fixedly connected to the side beams arranged on the same side. Two crossbeams are horizontally installed on the upper and lower parts of the platform, respectively, with their ends connected to the upper or lower parts of the platform. The side beams are fixedly connected; the front and rear uprights are respectively installed at the front and rear ends of the optical engine support platform; the front window cover is set on the front upright, the target support frame and the target locking block are both installed on the rear upright, and the rear upright is also provided with a primary mirror mounting hole, and a pressure ring is installed in the primary mirror mounting hole; the bottom of the lower crossbeam is also provided with a foot pad; the right side plate, bottom plate, left side plate and top cover plate are fixed to the side beam, crossbeam and upright beam by screws; the target replacement window is installed on the right side plate and the rear upright by hinges and spring screws; handles are respectively installed on the left side plate and the right side plate; The reflective collimating optical system includes a primary mirror, an aperture diaphragm support, an aperture diaphragm, a secondary mirror, and a six-dimensional adjustment mechanism. The primary mirror is mounted on the rear panel and is vibration-isolated and fixed to the rear panel by optical adhesive and a pressure ring. The secondary mirror is mounted on the front panel via the six-dimensional adjustment mechanism. The aperture diaphragm is mounted on the side beam on the lower right side via an aperture diaphragm support. The variable temperature difference target generator includes a surface source blackbody, a target, and a blackbody controller. The surface source blackbody is mounted on the rear upright plate. The target is inserted into the target support frame and fixed by the target clamping block. The blackbody controller is connected to the power supply, industrial control computer, and surface source blackbody via a cable.

2. The portable miniature thermal imager integrated maintenance and testing equipment as described in claim 1, characterized in that... This testing equipment is used for SiTF / NETD, MRTD, MTF, and optical axis consistency testing of infrared thermal imagers. The specific testing steps are as follows: 1) SiTF / NETD Measurement: SiTF tests the response function of a thermal imager, which characterizes the imager's ability to convert input temperature changes into electrical or image signals. During testing, the thermal imager is placed in front of the collimator window, and its video signal is connected to an industrial computer. A suitable semi-circular or circular target is placed in the target holder, ensuring a clear image is centered on the imager's field of view. The maximum temperature difference is then set. and minimum temperature difference The sampling number N and the blackbody target test area are determined, and the measurement begins. The blackbody controller causes the blackbody and the target to form a differential signal. After being reflected by the reflective collimator, a temperature difference signal target is formed at approximately infinity. The test image received by the thermal imager under test, and the signal output received by the acquisition card, are represented as follows: In the formula, G is the system gain of the thermal imager under test. Let be the response function of the thermal imager under test. To enable the thermal imager to effectively detect the element area, This refers to the optical f-number of the thermal imager. For spectral radiance, The transmittance of the thermal imager under test. To test the transmittance of the system and the test environment, the signals collected during the test are discrete data points. The least squares method is used to fit the data to obtain the SiTF curve, and the slope of the curve is the system responsivity. The calculation formula is: Fourier transform is performed on the acquired image signals to analyze the noise distribution in the frequency domain and obtain the noise power spectrum (NPS) curve. Multiple frames of images are acquired, and the voltage fluctuation of each pixel over time is calculated. After removing the inter-frame average, the root mean square (RMS) value of the remaining fluctuation is calculated to obtain the root mean square noise (NETD). Based on the SiTF and MRS test results, the NETD is calculated using the following formula: The noise root mean square (RMS) is represented by SiTF, which is the signal transfer function, and finally converted to mk. 2) MRTD Measurement: During testing, the thermal imager is placed on the testing platform, ensuring its optical axis is at the same horizontal level as the main optical axis of the testing equipment. A four-bar target corresponding to the required spatial frequency is selected, and the temperature of the blackbody is controlled to ensure that the positive contrast four-bar target image is clearly distinguishable. At this point, the temperature difference is... ,from Start cooling until the four-bar target image with positive contrast is no longer distinguishable; the temperature difference at this point is the measured positive temperature difference. Adjust the blackbody temperature difference to make the negative contrast four-bar target image clearly distinguishable; at this point, the temperature difference is... ,from Start heating until the negative contrast of the four-bar target image is indistinguishable; the temperature difference at this point is the measured negative temperature difference. The MRTD at the tested spatial frequency point is calculated using the following formula: Obtain MRTD measurement values; 3) MTF measurement: During the test, the thermal imager is placed on the test stage, with its optical axis at the same horizontal level as the main optical axis of the test equipment. A four-bar target or a slit target is selected for testing. The blackbody temperature difference of the test equipment is adjusted. Within the test area, the response values ​​of all rows of pixels in each column are averaged first. Then, the average response value of each pixel in the averaged row is calculated for N frames. The knife-edge response curve is obtained from these average response values. The knife-edge response curve is differentiated, and after Fourier transform and normalization, the MTF curve can be obtained. 4) Optical axis consistency measurement: Select a point target or a crosshair target as the test target. Focus the camera clearly within the test reference field of view. Adjust the test stage so that the center of the thermal imager's crosshair reticle coincides with the center of the crosshair target image or the point target image, obtaining the coordinates of the first target point. Switch the thermal imager to another field of view, reselect the target measurement area, and obtain the coordinates of the second target point. Then calculate the deviation value of the thermal imager's optical axis consistency using the following formula: The azimuth deviation between two measurements of the target coordinates. For pitch deviation; The test results of optical axis consistency offset value were obtained.

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