JT refrigeration infrared focal plane detector newly-added blind pixel detection method considering air source quality fluctuation

Abstract

The invention provides a JT refrigeration infrared focal plane detector newly-added blind pixel detection method considering air source quality fluctuation, and belongs to the field of blind pixel detection. The problem that the imaging quality of an infrared imaging system is damaged due to blind pixels of an infrared detector caused by air source quality fluctuation is solved; comprising the following steps: aligning a JT refrigeration infrared focal plane detector in a normal working state to a surface source black body, and enabling a JT refrigerator to be in a stable operation state; turning off a gas source switch, starting to store output image data of the detector, and monitoring an output voltage signal of a temperature measuring diode of the detector; when the output voltage signal of the detector temperature measuring diode is reduced to a set threshold value, data storage is automatically stopped; reading back the existing blind pixel coordinate data of the detector stored in the infrared imaging system; calculating a newly added blind pixel in the stored image data; sequencing the existing blind pixels and the newly added blind pixels to generate a new blind pixel coordinate file; the method is applied to the blind pixel detection of the JT refrigeration infrared focal plane detector.

Description

Technical Field

[0001] The present invention provides a method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector considering the fluctuation of gas source quality, belonging to the technical field of blind pixel detection. Background Technique

[0002] JT-cooled infrared focal plane detectors are widely used in various types of precision-guided weaponry due to their advantages such as small size, light weight, fast startup, and high sensitivity. However, when such equipment operates, high-quality high-pressure gas needs to be provided. Once the gas source quality fluctuates, it will cause blind pixels in the imaging system, damaging the image output quality of the infrared imaging system and affecting the detection and tracking of targets by precision-guided weapons.

[0003] High-sensitivity infrared focal plane detectors usually operate in an ultra-low temperature environment (generally 80 - 90K (-183°C to -193°C) and below), and a cooler is required to create a low-temperature environment for them. At the same time, the system will monitor the output voltage of the temperature-measuring diode inside the detector to judge the temperature inside the detector dewar, that is, the working state. Among them, JT coolers are widely used due to their advantages such as small size, light weight, and fast startup. JT coolers use the high-pressure gas expansion cooling effect to create a low-temperature environment. During use, high-quality high-pressure nitrogen is generally used.

[0004] When the gas source quality fluctuates, it will have a greater impact on the JT cooler, thereby increasing the temperature inside the detector. By studying the IV characteristics of infrared focal plane pixels (essentially photodiodes), as Figure 1 shown, for an infrared focal plane detector in the reverse-biased working state, the leakage current of individual pixels will be relatively large as the ambient temperature rises (as shown by the red curve). The diode leakage current and the photocurrent are superimposed together. After being converted into voltage by the readout circuit and sampled by A / D, it will appear as bright blind pixels with a relatively high gray value on the image. Summary of the Invention

[0005] In order to solve the problem that the fluctuation of gas source quality causes blind pixels in the infrared detector and then damages the imaging quality of the infrared imaging system, the present invention proposes a method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector considering the fluctuation of gas source quality.

[0006] The technical solution adopted by the present invention is as follows: A method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector considering the fluctuation of gas source quality, including the following steps: S1: Align the JT-cooled infrared focal plane detector in the normal working state with a surface source blackbody, and make the JT cooler in a stable operating state; S2: Close the gas source switch, start saving the output image data of the detector, and at the same time monitor the output voltage signal of the detector temperature-measuring diode; S3: When the output voltage signal of the detector's temperature-measuring diode drops to the set threshold value, automatically stop data saving; S4: Read back the existing blind pixel coordinate data of the detector stored in the infrared imaging system; S5: Calculate the newly added blind pixels in the image data stored in step S2; S6: Generate a new blind pixel coordinate file after sorting the blind pixels in steps S4 and S5.

[0007] Furthermore, the set threshold range of the output voltage signal of the detector's temperature-measuring diode in step S3 is set according to the range of the temperature rise inside the detector dewar.

[0008] Furthermore, control the temperature rise inside the detector dewar within 4°C to 5°C.

[0009] Furthermore, the set threshold range of the output voltage signal of the detector's temperature-measuring diode is 8 mV - 12.5 mV.

[0010] Furthermore, in step S5, calculate the position and quantity of the newly added blind pixels through the mean square error of the sliding window.

[0011] Furthermore, the existing blind pixel coordinate data in step S4 is the original blind pixel coordinates after the detector is factory-calibrated or the previous calibration data after the detector has been used after leaving the factory.

[0012] Even further, burn the new blind pixel coordinate file into the product using the JT-cooled infrared focal plane detector, and perform a read-back verification.

[0013] A computer device includes a memory, a processor, and a computer program stored on the memory, and the processor executes the computer program to implement the steps of the method.

[0014] A computer-readable storage medium has a computer program / instructions stored thereon, and when the computer program / instructions are executed by a processor, the steps of the method are implemented.

[0015] A computer program product includes a computer program / instructions, and when the computer program / instructions are executed by a processor, the steps of the method are implemented.

[0016] The beneficial effects of the present invention compared with the prior art are as follows: The present invention uses the process of shutting off the gas source to simulate the fluctuation of the gas source quality, judges the internal temperature rise of the dewar by monitoring the output voltage of the detector's temperature-measuring diode, and detects and eliminates the blind pixels generated at a certain temperature rise inside the dewar in advance, reducing the probability of newly added blind pixels due to the fluctuation of the gas source quality during the use of the infrared imaging system, and improving the reliability and stability of the infrared imaging system. Description of the Drawings

[0017] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1 It is the IV characteristic diagram of the pixels of the focal plane detector varying with temperature; Figure 2 It is the monitoring flow chart of the method of the present invention. Specific embodiments

[0018] As Figure 2 shown, the present invention provides a method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector considering the fluctuation of gas source quality. It ingeniously uses the process of shutting off the external gas source of the JT-cooled infrared focal plane detector to simulate the fluctuation of gas source quality. By collecting the image data of the JT-cooled infrared focal plane detector during this process, the unrobust and potential hazard pixels in the detector can be detected in advance, and these pixels are eliminated, ensuring the performance of the weapon equipment during use and reducing the probability of device maintenance. Moreover, the method of the present invention can be used for the secondary calibration after the detector is factory-calibrated, and can also be used for the re-calibration of the detector that has been installed on the weapon equipment after being used for a period of time (or regular calibration at regular intervals), and it is not necessary to separately remove the detector for detection, improving the detection efficiency.

[0019] The method of the present invention includes steps such as image acquisition, monitoring the output voltage of the detector's temperature-measuring diode, automatically controlling image saving according to the diode voltage value, blind pixel judgment, reading back, merging, and programming of blind pixel coordinates. The specific implementation process is as follows: 1) Align the JT-cooled infrared focal plane detector with the surface source blackbody, and it is in a normal working state, and make the JT cooler in a stable operating state, that is, the regulator inside it is in a self-adjusting state with a smaller opening.

[0020] 2) Close the gas source switch, start saving the output image data of the detector, and at the same time monitor the output voltage signal of the detector's temperature-measuring diode.

[0021] 3) When the output voltage signal of the temperature-measuring diode drops to 10 mV, automatically stop data saving.

[0022] 4) Read back the original or existing blind pixel coordinates of the detector in the infrared imaging system.

[0023] 5) Calculate the newly added blind pixels in the image data stored this time.

[0024] 6) Programming of the merged blind pixels: After sorting the blind pixels in steps 4) and 5) in ascending order, generate a new blind pixel coordinate file, program it into the product, and perform a read-back verification.

[0025] In the present invention, the control threshold of the output voltage change value of the temperature-measuring diode is particularly crucial. When the threshold is relatively small, the temperature change in the detector dewar is not significant, and the non-robust pixels have not yet exhibited the state of dead pixels. When the threshold is relatively large, the change in the detector dewar is too large, and many pixels will be misjudged as dead pixels, affecting the use of the infrared imaging system. Generally, it is considered that when the temperature in the detector dewar increases by 1°C, the output voltage of the temperature-measuring diode increases by approximately 2 mV to 2.5 mV. Through a large number of experiments and tracking the subsequent addition of dead pixels during the use of the product, in this embodiment, the upper limit of the threshold is set to 10 mV, that is, when the decrease value of the output voltage of the temperature-measuring diode is controlled at 10 mV, and at this time, when the temperature rise in the detector dewar is controlled at 4°C to 5°C, the position and quantity of the dead pixels judged by a certain moving window mean square deviation detection standard best meet the use requirements of the infrared imaging system.

[0026] The method of the present invention has been used and verified on an infrared imaging system using a JT-cooled infrared focal plane detector. The inventive concept is ingenious, and the implementation method is simple and practical, greatly reducing the probability of new dead pixels occurring during the subsequent use of the detector and reducing the maintenance frequency of the system. Moreover, the technology used in the present invention has a high maturity level and strong practicability, filling the blank of how to handle new dead pixels caused by fluctuations in the gas source quality in an infrared imaging system using a JT-cooled infrared focal plane detector, and is easy to be implemented in engineering. Through the method of the present invention, the reliability and stability of the infrared imaging system can be greatly improved, and the maintenance frequency and cost are reduced. It has universality and has broad application and promotion prospects for infrared imaging systems using JT-cooled infrared focal plane detectors.

[0027] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A new blind pixel detection method for a JT-cooled infrared focal plane detector considering fluctuations in gas source quality, characterized in that: The following steps are involved: S1: Aim the JT-cooled infrared focal plane detector in normal working state at the surface source black body, and keep the JT cooler in stable operation state; S2: Turn off the gas source switch and start saving the output image data of the detector, while monitoring the output voltage signal of the temperature measuring diode of the detector; S3: When the output voltage signal of the temperature measuring diode of the detector drops to the set threshold, data saving will be automatically stopped; S4: Read back the existing blind element coordinate data of the detector stored in the infrared imaging system; S5: Calculate the newly added blind pixels in the image data stored in step S2; S6: Sort the blind pixels in steps S4 and S5 to generate a new blind pixel coordinate file.

2. According to claim 1, a method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector taking into account fluctuations in gas source quality, characterized in that: In step S3, the threshold range of the output voltage signal of the temperature measuring diode of the detector is set according to the range of the temperature rise in the detector dewar.

3. The method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector taking into account fluctuations in gas source quality according to claim 2, characterized in that: The temperature rise in the detector Dewar is controlled at 4℃~5℃.

4. The method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector taking into account fluctuations in gas source quality according to claim 3, characterized in that: The set threshold of the output voltage signal of the detector temperature measuring diode is 8mV-12.5mV.

5. The method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector taking into account fluctuations in gas source quality according to claim 1, characterized in that: In step S5, the position and number of the newly added blind pixels are calculated by the sliding window mean square error.

6. The method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector taking into account fluctuations in gas source quality according to claim 1, characterized in that: The existing blind pixel coordinate data in step S4 is the original blind pixel coordinates after the detector is calibrated before leaving the factory or the last calibration data after the detector has been used before leaving the factory.

7. A method for detecting newly added blind pixels in a JT-cooled infrared focal plane detector taking into account fluctuations in gas source quality according to any one of claims 1 to 6, characterized in that: Burn the new blind pixel coordinate file into the product using JT cooled infrared focal plane detector and perform a read-back verification.

8. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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