Research On Key Technologies Of Infrared Division-of-Focal-Plane Polarization Imaging Detection

Intensity and polarization are important physical properties of infrared radiation.Traditional infrared imaging technology can only obtain intensity information,while infrared polarization imaging technology can obtain intensity and polarization information at the same time.It is a cutting-edge imaging technology and has important application prospects in the field of target detection and remote sensing.At present,the infrared polarization imaging system mainly includes division-of-time polarimeter,division-of-amplitude polarimeter,division-of-aperture polarimeter and division-offocal-plane(DoFP)polarimeter.With the advantages of small volume and real-time imaging,the DoFP imaging system is a research hotspot in the field of infrared polarization imaging.In this paper,the polarization imaging system is built by using the domestic self-developed infrared DoFP polarization detector,and the key technologies of infrared polarization imaging detection are studied:(1)The factors that affect the polarization detection performance of DoFP polarization detector are analyzed,and to verify the polarization detection performance of polarization imaging system,the transmission controllable infrared partial polarization radiation source is designed.The influence of extinction ratio and angle error of micro-polarizer array,and noise equivalent irradiance(NEI)of detector on the accuracy of polarization detection is analyzed,and the noise equivalent the degree of linear polarization(NeDoLP)is introduced to describe the detection precision of Do LP limited by noise.Based on the generation mechanism of infrared polarization,a set of the transmissive controllable infrared partial polarization radiation source is designed.By adjusting the incident angle,the infrared radiation with DoLP ranging from 0 to 0.48 can be generated,and the difference between the theoretical value and the measured value is less than 1.65%,which meets the needs of polarization detection performance verification of infrared DoFP polarization camera.(2)Aiming at the problem of non-uniformity of infrared DoFP camera,a method of camera calibration and non-uniformity correction is proposed.Firstly,the response model of DoFP camera pixel is established,and the factors that affect the nonuniformity of polarization image are analyzed.On this basis,a correction algorithm for camera response and polarization correction is proposed,which can effectively improve the uniformity of image.Finally,the extended multi-channel interpolation algorithm and dead pixel replacement algorithm based on adjacent pixels and redundant information are proposed to improve the image quality.(3)For the noise in the DoFP polarization image,an improved principal component analysis(PCA)algorithm is proposed.By analyzing the source of the camera noise and calculating the time noise of the camera,the main noise in the DoFP polarization image is determined.Based on the non-local self-similarity of the infrared DoFP polarization image and the dimensionality reduction characteristics of the PCA,an improved PCA algorithm for infrared DoFP polarization image denoising is proposed.The simulation and real DoFP polarization images are used to verify the effect of the algorithm,and the results show that the algorithm has a good effect in suppressing image noise and improving image quality.(4)A high-speed infrared DoFP polarization imaging system is designed and built in this paper,and the performance of the imaging system is analyzed and verified.The DoFP polarization imaging system can realize the functions of image acquisition,transmission,processing,display and storage.In order to analyze and verify the performance of the infrared DoFP polarization imaging system,the noise and NEI of the system are tested firstly.Then,NeDoLP,polarization detection accuracy and precision of the system are tested by using the self-developed transmission controllable infrared partial polarization radiation source,and the maximum measurement error of Do LP is less than 1.05%,and NeDoLP less than 0.0256,which meets the needs of infrared polarization detection.Finally,the UAV is taken as the detection target,and different scene images are collected by the camera.The detection effect of infrared intensity and DoLP image is analyzed,and the results show that DoLP image can improve the detection performance of the system.