New blind pixel detection method for JT-cooled infrared focal plane detector considering gas source quality fluctuation

Abstract

The present invention provides a method for detecting newly added blind pixels of a JT-cooled infrared focal plane detector taking into account fluctuations in gas source quality, belonging to the field of blind pixel detection. The method solves the problem that blind pixels appear in infrared detectors due to fluctuations in gas source quality, thereby damaging the imaging quality of an infrared imaging system. The method comprises the following steps: aligning a JT-cooled infrared focal plane detector in a normal working state with a surface source blackbody, and placing the JT refrigerator in a stable operating state; turning off a gas source switch, starting to save output image data of the detector, and simultaneously monitoring an output voltage signal of a temperature measuring diode of the detector; automatically stopping data saving when the output voltage signal of the temperature measuring diode of the detector drops to a set threshold; reading back existing blind pixel coordinate data of the detector stored in the infrared imaging system; calculating newly added blind pixels in the stored image data; and generating a new blind pixel coordinate file after sorting the existing and newly added blind pixels. The present invention is applicable to blind pixel detection of JT-cooled infrared focal plane detectors.

Description

Technical Field

[0001] The present invention provides a new blind pixel detection method for a JT refrigerated infrared focal plane detector taking into account fluctuations in gas source quality, belonging to the technical field of blind pixel detection. Background Art

[0002] JT cooled infrared focal plane detectors are widely used in various types of precision-guided weapons and equipment due to their advantages such as small size, light weight, fast startup and high sensitivity. However, such equipment requires high-quality high-pressure gas when working. Once the gas source quality fluctuates, blind pixels will appear 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 typically operate in ultra-low temperature environments (typically 80-90K (-183°C to -193°C) and below), requiring a cryocooler to maintain this low temperature. The system also monitors the output voltage of the detector's internal temperature-sensing diode to determine the temperature within the detector's dewar, thereby determining its operating status. JT coolers are widely used due to their small size, light weight, and fast startup. JT coolers utilize the cooling effect of high-pressure gas expansion to create a low-temperature environment. High-quality, high-pressure nitrogen is typically used.

[0004] When the gas source quality fluctuates, it will have a significant impact on the JT cooler, causing the internal temperature of the detector to rise. By studying the IV characteristics of infrared focal plane pixels (essentially photodiodes), such as Figure 1 As shown in the figure, for an infrared focal plane detector in a reverse biased working state, the diode leakage current of some pixels will be larger as the ambient temperature rises (as shown by the red curve). The diode leakage current is superimposed on the photocurrent, and after being converted into voltage by the readout circuit and A / D sampling, it will appear as a bright blind pixel with a higher grayscale value on the image. Summary of the Invention

[0005] In order to solve the problem that blind pixels appear in infrared detectors due to fluctuations in gas source quality, thereby damaging the imaging quality of infrared imaging systems, the present invention proposes a new blind pixel detection method for JT cooled infrared focal plane detectors that takes gas source quality fluctuations into consideration.

[0006] The technical solution adopted by the present invention is: a new blind pixel detection method for a JT cooled infrared focal plane detector considering the fluctuation of gas source quality, comprising the following steps:

[0007] S1: Aim the JT cooled infrared focal plane detector in normal working state at the surface source blackbody, and make the JT cooler in stable operating state;

[0008] S2: Turn off the gas source switch and start saving the detector's output image data while monitoring the output voltage signal of the detector's temperature measuring diode;

[0009] S3: When the output voltage signal of the detector's temperature measuring diode drops to the set threshold, data saving will automatically stop;

[0010] S4: Read back the existing blind element coordinate data of the detector stored in the infrared imaging system;

[0011] S5: Calculate the newly added blind pixels in the image data stored in step S2;

[0012] S6: Sort the blind pixels in steps S4 and S5 and generate a new blind pixel coordinate file.

[0013] Furthermore, 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.

[0014] Furthermore, the temperature rise inside the detector Dewar is controlled at 4°C~5°C.

[0015] Furthermore, the set threshold range of the output voltage signal of the detector temperature measuring diode is 8mV-12.5mV.

[0016] Furthermore, in step S5, the position and number of the newly added blind pixels are calculated by using the sliding window mean square error.

[0017] Furthermore, the existing blind pixel coordinate data in step S4 is the original blind pixel coordinates after the detector is calibrated at the factory or the last calibration data after the detector has been used at the factory.

[0018] Furthermore, the new blind element coordinate file is burned into the product using the JT cooled infrared focal plane detector and read back for verification.

[0019] A computer device comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method.

[0020] A computer-readable storage medium stores a computer program / instruction thereon, which implements the steps of the method when executed by a processor.

[0021] A computer program product comprises a computer program / instructions which, when executed by a processor, implement the steps of the method.

[0022] Compared with the prior art, the present invention has the following beneficial effects: the present invention utilizes the process of shutting off the gas source to simulate the gas source quality fluctuation, judges the temperature rise inside the dewar by monitoring the output voltage of the detector temperature measuring diode, detects and eliminates the blind pixels generated when the temperature rises inside the dewar in advance, reduces the probability of new blind pixels caused by gas source quality fluctuation during the use of the infrared imaging system, and improves the reliability and stability of the infrared imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings:

[0024] Figure 1 is the IV characteristic diagram of the focal plane detector pixel as the temperature changes;

[0025] Figure 2 4 is a monitoring flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] like Figure 2 As shown, the present invention provides a new blind pixel detection method for JT-cooled infrared focal plane detectors that takes into account fluctuations in gas source quality. This method cleverly utilizes the process of shutting off the external gas source of the JT-cooled infrared focal plane detector to simulate gas source quality fluctuations. By collecting image data from the JT-cooled infrared focal plane detector during this process, weak pixels in the detector with potential hazards can be detected in advance and eliminated, ensuring the performance of weapons and equipment during use and reducing the probability of device maintenance. Furthermore, the present method can be used for secondary calibration of detectors after factory calibration. It can also be used to recalibrate detectors installed on weapons and equipment after a period of use (or for regular calibration at regular intervals). It eliminates the need to remove the detectors individually for testing, thereby improving detection efficiency.

[0027] The method of the present invention includes the steps of image acquisition, detector temperature measurement diode output voltage monitoring, diode voltage value automatic control image storage, blind pixel determination, blind pixel coordinates readback, merging and burning. The specific implementation process is as follows:

[0028] 1) Aim the JT cooled infrared focal plane detector at the surface source blackbody, which is in normal working state, and make the JT cooler in stable operation state, that is, its internal regulator is in the self-adjusting state with a small opening.

[0029] 2) Turn off the gas source switch and start saving the detector's output image data while monitoring the output voltage signal of the detector's temperature measuring diode.

[0030] 3) When the output voltage signal of the temperature measuring diode drops to 10mV, data saving will stop automatically.

[0031] 4) Read back the original or existing blind element coordinates of the detector in the infrared imaging system.

[0032] 5) Calculate the newly added blind pixels in the image data stored this time.

[0033] 6) Blind cell programming after merging: Sort the blind cells in steps 4) and 5) in ascending order, generate a new blind cell coordinate file, program it into the product, and perform a readback verification.

[0034] In the present invention, the control threshold of the change in the output voltage of the temperature-measuring diode is particularly critical. When the threshold is low, the temperature change in the detector dewar is small, and weak pixels do not yet exhibit blind pixel status. When the threshold is high, the change in the detector dewar is too large, and many pixels may be misidentified as blind pixels, affecting the use of the infrared imaging system. Generally speaking, it is believed that for every 1°C increase in the temperature in the detector dewar, the output voltage of the temperature-measuring diode increases by approximately 2mV to 2.5mV. Through extensive testing and tracking the increase in blind pixels during subsequent product use, this embodiment sets the upper threshold limit to 10mV. That is, when the output voltage of the temperature-measuring diode decreases by 10mV, and the temperature rise in the detector dewar is controlled at 4°C to 5°C, the position and number of blind pixels determined using a sliding window mean square error detection standard best meet the use requirements of the infrared imaging system.

[0035] 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 invention has an ingenious concept and a simple and practical implementation method, which greatly reduces the probability of new blind pixels appearing in the detector during subsequent use and reduces the maintenance frequency of the system. In addition, the technology used in the present invention is highly mature and practical, filling the gap in how to deal with new blind pixels generated by fluctuations in gas source quality in infrared imaging systems using JT-cooled infrared focal plane detectors, and is easy to implement through engineering. The method of the present invention can greatly improve the reliability and stability of the infrared imaging system and reduce the maintenance frequency and cost. It is universal and has broad application and promotion prospects for infrared imaging systems using JT-cooled infrared focal plane detectors.

[0036] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to 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 that takes into account fluctuations in gas source quality, characterized by: The following steps are involved: S1: Aim the JT cooled infrared focal plane detector in normal working state at the surface source blackbody, and make the JT cooler in stable operating state; S2: Turn off the gas source switch and start saving the detector's output image data while monitoring the output voltage signal of the detector's temperature measuring diode; S3: When the output voltage signal of the detector's temperature measuring diode drops to the set threshold, data saving will automatically stop; 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 and generate a new blind pixel coordinate file.

2. The method for detecting blind pixels in a JT-cooled infrared focal plane detector considering fluctuations in gas source quality according to claim 1, 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 blind pixels in a JT-cooled infrared focal plane detector considering 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 in 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 in 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 using the sliding window mean square error.

6. The 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 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 at the factory or the last calibration data after the detector has been used at the factory.

7. A method for detecting 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 element coordinate file into the product using the JT cooled infrared focal plane detector and perform a readback verification.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, wherein: 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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