CN-121829763-B - Calibration method of polarization focal plane imaging system and imaging system

CN121829763BCN 121829763 BCN121829763 BCN 121829763BCN-121829763-B

Abstract

A calibration method and an imaging system of a polarization focal plane imaging system relate to the field of photoelectric imaging and remote sensing detection imaging, and solve the problems that the existing polarization error correction technology has low correction efficiency and is difficult to correct a polarization state change system. The calibration method is based on the acquired uniform light field, and a plurality of coding patterns and corresponding polarization modulation matrixes are obtained and used as calibration results. The polarization error correction method comprises the steps of obtaining an observation intensity vector based on a target scene, obtaining a corresponding polarization modulation matrix based on a coding pattern according to a coding polarization modulation matrix lookup table, further obtaining a downsampled Stokes vector after correcting polarization errors, and completing correction of the polarization errors through an imaging reconstruction method. A polarized focal plane splitting imaging system comprises an imaging lens, a DMD digital micromirror array coding module, a focal plane splitting DoFP polarization detector and an imaging reconstruction module. The method is suitable for the fields of remote sensing detection, target identification, environment monitoring and the like.

Inventors

WANG CHAO
WU XINGJIE
Pei Yushuai
FU QIANG
LIU JIANAN
LIU ZHUANG
WANG QI

Assignees

长春理工大学

Dates

Publication Date: 20260512
Application Date: 20260312

Claims (8)

1. The calibration method of the polarization focal plane splitting imaging system is characterized in that the polarization focal plane splitting imaging system comprises the following steps: the front imaging lens is used for projecting a light field of a target scene to the DMD digital micro-mirror array coding module to form an optical image, and Stokes vectors of the obtained optical image are as follows ; DMD digital micromirror array coding module capable of generating A plurality of coding patterns for using any one of the coding patterns For the Stokes vector Coding and modulating, wherein the optical image after coding and modulating is projected to a relay imaging lens, and the Stokes vector of the light field is that , =1,2,......, ; The relay imaging lens projects the optical image to a focal plane DoFP polarization detector; the focal plane DoFP polarization detector performs exposure imaging and obtains a polarization response vector ; The calibration method comprises the following steps: the DMD digital micro-mirror array coding module sequentially generates 1 coding pattern For each of the coding patterns Sequentially setting the target scenes into Uniform light field of seed polarization state is obtained Group polarization parameters based on Obtaining corresponding polarization modulation matrix by group polarization parameters ; Will be Each code pattern and corresponding code pattern The polarization modulation matrixes are combined into a coded polarization modulation matrix lookup table to be used as a calibration result of the polarization focal plane splitting imaging system; By passing through Obtaining Stokes vectors after correction of polarization errors , wherein, For the polarization modulation matrix Is a pseudo-inverse of (a); the said The group polarization parameters include Stokes vectors And its corresponding polarization response , ; The Stokes vector By passing through The calculation results show that the obtained product is, Is the first Stokes vectors corresponding to uniform light fields of the seed polarization state, wherein, Is a band-by-band point multiplication and integration in the spectral dimension.
2. The method of calibrating a polarization split focal plane imaging system according to claim 1, wherein the steps of A uniform field of polarization is generated using a high precision polarization generator.
3. The method of calibrating a polarization split focal plane imaging system according to claim 1, wherein the steps of 16, The polarization states include 4 circular polarization states and 12 linear polarization states.
4. The method of calibrating a polarization split focal plane imaging system according to claim 1, wherein the steps of 12, The polarization states comprise 12 linear polarization states.
5. The method for calibrating a polarization focal plane splitting imaging system according to claim 1, wherein the exposing and imaging of the polarization detector of the focal plane splitting DoFP comprises extracting intensity response values of four polarization channels of each super pixel to form a polarization response vector The polarization angles of the four polarization channels are respectively 0 degrees, 45 degrees, 90 degrees and 135 degrees.
6. The method of calibrating a polarization split focal plane imaging system according to claim 1, wherein said calibrating is based on said polarization split focal plane imaging system Obtaining corresponding polarization modulation matrix by group polarization parameters The method of (1) adopts least square method to minimize error function The realization is that, among other things, Is that Polarization response for group polarization parameters The matrix is formed by a matrix of the components, Is that Stokes vector corresponding to uniform light field of group polarization state A matrix is formed.
7. The method of calibrating a polarization focal plane imaging system according to claim 1, wherein the polarization response Is directed to the first The uniform light field of the polarization state is divided into a focal plane DoFP and a polarization response vector obtained when the polarization detector is exposed and imaged.
8. The polarization focal plane splitting imaging system is characterized by comprising a front imaging lens (2), a DMD digital micromirror array coding module (3), a relay imaging lens (4), a focal plane DoFP polarization detector (5) and an imaging reconstruction module; the front imaging lens (2) is used for projecting the light field of the target scene (1) to the DMD digital micro-mirror array coding module to form an optical image, and the Stokes vector of the optical image is ; The DMD digital micro-mirror array coding module can generate A plurality of coding patterns for using any one of the coding patterns For the Stokes vector Coding and modulating, wherein the optical image after coding and modulating is projected to a relay imaging lens, and the Stokes vector of the optical image is as follows , =1,2,......, ; The relay imaging lens projects the optical image to the focal plane DoFP polarization detector; the focal plane DoFP polarization detector performs exposure imaging and obtains a polarization response vector ; The imaging reconstruction module is used for being based on the coding pattern Obtaining a corresponding polarization modulation matrix according to the coded polarization modulation matrix lookup table ; The coded polarization modulation matrix lookup table is obtained by the calibration method of the coded polarization modulation matrix according to any one of claims 1 to 7; And also for passing through Obtaining Stokes vectors after correction of polarization errors , wherein, For the polarization modulation matrix Is a pseudo-inverse of (a); and also for based on the Stokes vector The Stokes vector after the code modulation is subjected to an imaging reconstruction method Decoding and reconstructing to obtain a polarized image of the target scene with the polarization error removed, and correcting the polarization error to obtain a reconstructed image.

Description

Calibration method of polarization focal plane imaging system and imaging system Technical Field The invention relates to the field of photoelectric imaging and remote sensing detection imaging, in particular to the field of polarization imaging. Background The polarization state of the light carries physical information such as target surface texture, roughness, complex refractive index and the like which cannot be obtained by intensity detection. In the field of remote sensing detection, the polarization imaging technology has remarkable advantages in the aspects of cloud and fog removal, camouflage identification, sea surface oil spill monitoring and the like. With the increasing demands of applications, future polarization detection must be moving towards higher spatial resolution and higher radiation/polarization measurement accuracy. The focal plane (Division of Focal Plane, doFP) polarization detector is a current mainstream detection mode due to the characteristics of compact structure and real-time imaging. The detector is generally integrated with a plurality of micro polarizers with different polarization directions in the same focal plane, and can acquire intensity images with a plurality of polarization directions under the condition of single exposure, thereby realizing instantaneous detection of polarization information. The focal plane polarization detector has the advantages of compact structure, instantaneous imaging and the like, but the inherent imaging mode also introduces a plurality of problems which are difficult to ignore: (1) Spatial resolution loss-due to the 2x2 array arrangement of the four micropolarizers of different polarization directions (0, 45, 90, 135), the single channel resolution of the output image is only 1/4 of the detector physical resolution. (2) The instantaneous field error is that the pixel positions corresponding to different polarization directions have space dislocation, so that the field inconsistency problem between polarization channels is easily introduced, thereby causing artifacts to appear at the detection edge or the high-frequency texture region and affecting the resolution precision of the polarization parameters. The technology of computing optical imaging is rapidly developed, and the technology breaks through the limitations of the traditional imaging system in terms of resolution, information dimension and system flexibility to a certain extent through the mode of combining hardware optical coding with a computing reconstruction algorithm. Among them, an imaging method based on a spatial light Modulator (SPATIAL LIGHT Modulator, SLM) (such as DMD, liquid crystal spatial light Modulator, etc.) is one of important implementation forms of computing imaging. To break through the physical limitations of traditional optics, computational optical imaging techniques based on optical code modulation were introduced into polarization-division focal plane detection systems. The system performs time sequence or space coding on an incident light field, performs information demodulation and reconstruction by combining an algorithm, and can solve the problems of DoFP of resolution reduction and instantaneous field error by matching hardware optical coding with algorithm reconstruction (such as compressed sensing, super-resolution reconstruction and spectrum reconstruction), acquire a high-resolution image and improve imaging quality. However, such computed imaging systems based on polarization focal planes typically have a large amount of polarization error, resulting in poor imaging contrast and poor polarization detector accuracy. The main sources of polarization errors are two parts, namely polarization errors introduced by DoFP imaging modes, and the polarization errors comprise (1) crosstalk between pixels and polarization crosstalk, wherein the crosstalk phenomenon exists between different polarization channels due to the influence of a micro-polarizer manufacturing process and coupling between pixels, so that the measured polarization state deviates from a true value. (2) Extinction ratio and non-uniformity limitations the extinction ratio of micro-polarizers is typically lower than that of conventional crystal polarizers, and the non-uniformity of the response of each pixel can directly introduce fixed pattern noise, severely affecting the inversion accuracy of the stokes vector. The second is the polarization error introduced by the coded aperture computed imaging, including (1) systematic complexity errors-adding coded aperture elements and relay optics (lenses, prisms, etc.) introduces additional aberrations and optical path alignment errors. (2) The encoding process changes the polarization state of light, for example, using a digital micromirror array (DMD), and the oblique reflection characteristics of the DMD micromirrors cause polarization-dependent reflection efficiency changes and phase differences, thereby changing the polarization state of