The degree of linear polarization (DOLP) expressions at any polarizer direction (PD) was deduced based on the Stokes vector and Mueller matrix. The average gray level range of the target units (20x20 pixels material) under triple-waveband and low illumination condition was obtained with 46 kinds of experimental materials. This paper mainly explored that the influence factors of the error and stability of multi-PD DOLP was researched by the numerical analysis, and outdoors experiments were carried out to demonstrate the analysis method. Studies have shown that when detection angle was near specular reflection direction, when interval angle of PD between angle A and angle B, between angle A and angle C were set as the range (40°≤Φ<sub>AB</sub> ≤80°, Φ<sub>AC</sub> =2.06Φ<sub>AB</sub>), the standard deviation of DOLP was lower, but also polarization information obtained under low illumination condition was stable, and the numerical analysis was consistent with the experimental results.
Based on Stokes vector and Jones vector, the correlation between Mueller matrix elements and refractive index was studied with the result simplified, and through Mueller matrix way, the expression of refractive index inversion was deduced. The Mueller matrix elements, under different incident angle, are simulated through the expression of specular reflection so as to analyze the influence of the angle of incidence and refractive index on it, which is verified through the measure of the Mueller matrix elements of polished metal surface. Research shows that, under the condition of specular reflection, the result of Mueller matrix inversion is consistent with the experiment and can be used as an index of refraction of inversion method, and it provides a new way for target detection and recognition technology.
The degree of linear polarization (DOLP) expressions at any polarizer direction (PD) was deduced based on the Stokes vector and Mueller matrix. The outdoors experiments were carried out to demonstrate the expressions. This paper mainly explored the DOLP-image-Contrast (DOLPC) between the target image and the background image, and the PD and RGB waveband that be considered two important influence factors were studied for camouflage target polarization detection. It was found that the DOLPC of target and background was obviously higher than intensity image. When setting the reference direction that polarizer was perpendicular to the incident face, the DOLP image of interval angle 60 degree between PD and reference direction had relatively high DOLPC, the interval angle 45 degree was the second, and the interval angle 35 degree was the third. The outdoors polarization detection experiment of controlling waveband showed that the DOLPC results was significantly different to use 650nm, 550nm and 450nm waveband, and the polarization detection performance by using 650nm band was an optimization method.
Proc. SPIE. 9796, Selected Papers of the Photoelectronic Technology Committee Conferences held November 2015
KEYWORDS: Mathematical modeling, Solar radiation models, Data modeling, Skin, Far infrared, Infrared radiation, Radiation effects, Solar radiation, Performance modeling, Thermal modeling, Atmospheric modeling, Temperature metrology
The characteristic of the self-infrared radiation of airplane-skin is very important for the stealth performance of airplane. Based on the theory of the airplane-skin temperature field, the distribution of the atmospheric temperature field and the principle of the black-body radiation function the self-infrared radiation model was established. In specified flight conditions, the influence of the atmospheric temperature, the speed of flight, the emissivity and the sight angle detection on the self-infrared radiation of the airplane skin were analyzed. Through the simulation of infrared radiation, some results under different flight states are obtained. The simulation results show that skin infrared radiation energy mainly concentrate on the far infrared wavebands, and various factors have different effects on the infrared radiation of skin. This conclusion can help reduce the infrared radiation and improve the stealth performance of airplane in the engineering design and the selection of flight conditions.
Using polarimetric information of the camouflaged target surface to identify camouflage has been a hot research area in camouflage detecting. The main method is to use the difference in the degree of polarization(DOP) between background and target to add the contrast ratio of them. The measurement of the DOP has some requirements on the intensity of reflected radiation. In case of low reflected radiation intensity, the difference in the DOP for different materials is not so distinguishable. In addition, the linear degree of polarization is largely under the effects of detection angle and surface roughness, so it is hard to differentiate the degree of polarization when the targets with similar surface roughness are detected at the same detection angle. By analyzing the elements affecting the reflected electromagnetic radiation amplitudes and phase on the camouflaged target surface, this article makes a research on the polarization character of reflected radiation A method on camouflaged target recognition directly or indirectly by taking the angle of ellipsometry (AOE) imaging under the linear polarized light. The function model of the angle of incidence, complex refractive index and AOE was modeled, then the model was simulated by MATLAB and the results showed it can describe the distribution properties of AOE. A new thought for the approach of identifying camouflaged target recognition by detecting polarimetric information was proposed, and it has a deep theoretical and practical significance in camouflaged target recognition.
Imaging unevenly is a problem to work out in laser display. The cause of imaging unevenly is analyzed in the paper firstly. In order to get even illumination, we use rotating polygon mirror with two-dimensional scanning and lens array to make the intensity distribution of Gaussian function become approximate even distribution. In order to reduce speckles, a rotating diffuser is used in our laser display system to produce the maximum speckle reduction with the minimum number of distinct phase Patterns. Finally the method is experimentally verified by taking example of green light.