CN-121994361-A - Dark current compensation method and device for thermal infrared imager

CN121994361ACN 121994361 ACN121994361 ACN 121994361ACN-121994361-A

Abstract

The invention provides a dark current compensation method and device for a thermal infrared imager, wherein the method comprises the steps of obtaining change data generated by the change of target parameters of each pixel along with the change of temperature in a detector of the thermal infrared imager, and generating a target corresponding relation table containing the target parameter-temperature corresponding relation of each pixel based on the change data, wherein the target parameter-temperature corresponding relation is matched with the dark current-temperature corresponding relation; when the thermal infrared imager measures temperature, a first target parameter generated by a dark pixel is obtained, the temperature of the corresponding current dark pixel is determined in a target corresponding relation table based on the first target parameter, the temperature distribution of all pixels on the detector is determined by combining the current temperature of the dark pixel and the heat transfer characteristics of the detector and each pixel, a second target parameter representing the current generation of each pixel is determined in the target corresponding relation table according to the temperature distribution, and the current temperature measurement result of the pixel is corrected according to the second target parameter of each pixel.

Inventors

YANG CAIWEN
ZHANG JIU
MENG FANLI
HE QING

Assignees

东北大学

Dates

Publication Date: 20260508
Application Date: 20251230

Claims (10)

1. The dark current compensation method of the thermal infrared imager is characterized by comprising the following steps of: Obtaining change data generated by the change of a target parameter of each pixel in a detector of the thermal infrared imager along with the change of temperature, and generating a target corresponding relation table containing a target parameter-temperature corresponding relation of each pixel based on the change data, wherein the target parameter-temperature corresponding relation is matched with a dark current-temperature corresponding relation; When the thermal infrared imager measures temperature, obtaining a first target parameter generated by a dark pixel, wherein the dark pixel is a pixel which does not participate in thermal imaging display; determining the temperature corresponding to the current dark pixel in the target corresponding relation table based on a first target parameter generated by the dark pixel; Determining the temperature distribution of all pixels on the detector by combining the current temperature of the dark pixels and the heat transfer characteristics among the detector and each pixel; determining a second target parameter representing the current generation of each pixel in the target corresponding relation table according to the temperature distribution; and correcting the current temperature measurement result of each pixel according to the second target parameter of the pixel.
2. The method for compensating for dark current in a thermal infrared imager according to claim 1, wherein obtaining the temperature-dependent data of the dark current of each pixel in the detector of the thermal infrared imager comprises: Obtaining change data of a target parameter of each pixel along with the change of temperature in the incubator in a detector of the thermal infrared imager in the incubator under the shading condition.
3. The thermal infrared imager dark current compensation method of claim 2, wherein the target parameter is a gray value of a pixel; obtaining variation data of a target parameter of each of the pixels with a variation of a temperature in the oven, comprising: Variation data of a gradation value of each of the pixels in accordance with a variation in temperature in the oven is obtained, the variation of the gradation value matching the variation of the dark current.
4. The thermal infrared imager dark current compensation method of claim 3, further comprising: Controlling the temperature in the incubator to change in a specified step size; the obtaining of the change data of the gray value of each pixel according to the temperature change in the incubator includes: Variation data is obtained for the temperature in the oven, each time the gray value of each pixel is generated in response to a variation of the temperature during a variation based on a specified step.
5. The thermal infrared imager dark current compensation method of claim 3, further comprising: Controlling the temperature in the incubator to maintain the changed temperature for a specified duration after each change based on a specified step length; obtaining change data of gray values of each pixel according to temperature change in the incubator, comprising: Variation data of the gray value of each pixel in response to the variation of the temperature during the maintenance of the varied temperature in the incubator is obtained.
6. The thermal infrared imager dark current compensation method of claim 1, wherein the generating a target correspondence table containing target parameter-temperature correspondence for each of the pixels based on the change data comprises: Generating a gray value-temperature relationship table containing a gray value-temperature correspondence of each of the pixels based on the change data; and determining the target corresponding relation table based on the gray value-temperature relation table.
7. The thermal infrared imager dark current compensation method of claim 1, wherein the obtaining a first dark current generated by a dark pixel comprises: Determining a current gray value of the dark pixel; a first dark current generated by the dark pixel is determined based on the current gray value.
8. The thermal infrared imager dark current compensation method of claim 1 or 7, wherein the dark pixels comprise a circle of pixels at the outermost edge of the detector and/or pixels at the center of the detector.
9. The thermal infrared imager dark current compensation method of claim 1, wherein said determining a temperature distribution of all pixels on the detector in combination with a current temperature of the dark pixels and heat transfer characteristics between the detector and each pixel comprises: and carrying out heat transfer analysis by combining the current temperature of the dark pixel and the heat transfer characteristics of the detector and each pixel, and estimating and determining the temperature distribution of all pixels on the detector, wherein the heat transfer analysis method comprises any one method of a linear interpolation method, a two-dimensional interpolation method and a finite difference method.
10. The utility model provides a thermal infrared imager dark current compensation arrangement which characterized in that includes: The first obtaining module is used for obtaining change data generated by the change of the target parameter of each pixel along with the change of the temperature in the detector of the thermal infrared imager, and generating a target corresponding relation table containing the target parameter-temperature corresponding relation of each pixel based on the change data, wherein the target parameter-temperature corresponding relation is matched with the dark current-temperature corresponding relation; The second obtaining module is used for obtaining a first target parameter generated by a dark pixel when the thermal infrared imager measures temperature, wherein the dark pixel is a pixel which does not participate in thermal imaging display; The first determining module is used for determining the temperature corresponding to the current dark pixel in the target corresponding relation table based on a first target parameter generated by the dark pixel; the second determining module is used for determining the temperature distribution of all pixels on the detector by combining the current temperature of the dark pixels and the heat transfer characteristics among the detector and each pixel; a third determining module, configured to determine, in the target correspondence table, a second target parameter that characterizes a current generation of each of the pixels according to the temperature distribution; And the correction module is used for correcting the current temperature measurement result of each pixel according to the second target parameter of each pixel.

Description

Dark current compensation method and device for thermal infrared imager Technical Field The embodiment of the invention relates to the technical field of thermal infrared imagers, in particular to a method and a device for compensating dark current of a thermal infrared imager. Background The thermal infrared imager detects infrared radiation emitted by a detected target, converts the infrared radiation into an electric signal, and obtains a temperature distribution image of the surface of the target through signal processing and temperature inversion. With the development of focal plane array detectors, thermal infrared imagers have been widely used in power inspection, equipment security, industrial detection, security monitoring, medical diagnosis, and other fields. In practical applications, even if no infrared radiation is incident, each pixel still generates a certain current output due to the existence of mechanisms such as thermal excitation of carriers in the semiconductor material of the infrared focal plane detector, junction leakage current, surface state recombination, and readout circuit input stage leakage, and the current is generally called dark current. The magnitude of the dark current is related to the detector materials, the process and the bias conditions, is particularly sensitive to the temperature, has a significant increasing trend along with the temperature rise of the detector, and meanwhile, the dark current between different pixels is obviously inconsistent due to the slight difference of the device structure and the process. On the other hand, because the dark current of each pixel is inconsistent, fixed pattern noise can be formed, and the output image still has stripes and patches under the condition of no incident infrared radiation. If the dark current cannot be accurately compensated, the temperature measurement result of the thermal infrared imager generates temperature drift, the quality of the generated image is obviously reduced, and the requirement of temperature measurement precision is difficult to meet. In the prior art, the compensation for dark current mainly includes the following modes: 1. And a dark field subtraction method of the whole shutter shielding is adopted. And controlling the whole shutter to shade the light path at a certain moment, collecting one or more dark field images as references, and directly subtracting the dark field images from the effective images in subsequent imaging to realize dark current compensation. The method is simple in implementation and visual in structure, but the obtained dark field image only corresponds to the temperature and the working state of the detector at the acquisition time, and a model of the dark current changing along with the temperature is not built. When the temperature and the working state of the detector change, the dark current drifts, the original dark field image rapidly fails, and the compensation precision is obviously reduced. In order to maintain a certain compensation effect, the dark field is required to be frequently and repeatedly shielded, so that the normal imaging process is interrupted, the continuous temperature measurement capability of the thermal infrared imager is affected, the action frequency of parts such as a mechanical baffle plate, an electromagnetic shutter and the like is high, and the mechanism abrasion and the service life reduction are easy to cause. 2. A method for global or local average temperature compensation by a temperature sensor. Setting one or several temperature sensors near the detector, measuring the temperature of the detector, shading and collecting dark field image in constant temperature, averaging the pixel output space in the whole or partial area to obtain average dark field grey value of different temperature points, setting up the corresponding relation between dark current and temperature by means of polynomial fitting or lookup table interpolation, etc. during the actual imaging, measuring the current temperature in real time by the temperature sensor, substituting the dark current-temperature relation to obtain whole or partial dark current bias, and subtracting the bias from the original image to realize temperature compensation. As the temperature sensor can only generally reflect the temperature information of the whole or partial position of the detector, when the temperature gradient exists in the detector, the actual temperature of each pixel cannot be accurately reflected based on a few temperature points, the dark current-temperature relationship is an average model of the whole or partial area, each pixel is not calibrated independently, the dark current-temperature characteristic of the pixel level is difficult to be accurately reflected, and fixed pattern noise and temperature measurement errors are easy to generate. To sum up, the dark current compensation method in the prior art generally has the following common problems: (1) The pixe