Polarization Imaging System And Application Based On Liquid Crystal Device

The polarization imaging system can detect the polarization information of the target,and obtain surface texture details,orientation information and other characteristics.By measuring the modulated intensity information,the polarization information of the scene can be calculated.The composite achromatic wave plate based on liquid crystal lens can improve the wavelength dependence of the modulation device and reduce the systematic error in the modulation process of intensity information.In this dissertation,we designed liquid crystal adjustable achromatic wave plate to improve the polarization imaging system,and then calibrated the measurement accuracy of the system.The specific content is as follows:First,the theoretical derivation of the design principle of the composite achromatic wave plate is carried out.Instead of the quartz wave plate,using liquid crystal variable retarders to realize the phase-adjustable design of the composite wave plate.Then,the numerical simulation of the designed ternary composite wave plate was carried out to verify the variability of its phase delay and achromatic band.Testing the performance of the wave plate,experiments have verified that the device has good achromatic characteristics in the 532 nm and 632 nm bands.Using optimizing the measurement method,the phase delay curve of the device in the visible light band has been obtained by,and the achromatic error is within 3%.Second,experiments were conducted to measure the accuracy of the polarization imaging system in detecting polarization characteristic parameters.Building two sets of optical paths to measure the various parameters of the Stokes vector,degree of polarization and polarization angle under the incident conditions of linearly polarized light and circularly polarized light of the system.By adjusting different angles and rotation directions,the error between the measured value and the theoretical value of the imaging system is compared.It is verified that the system can measure the full Stokes vector.And the measurement error of the system is reduced by using the designed liquid crystal composite variable wave plate.Third,realize the application of the highlight removal of the polarization imaging system.Optimize the way of the highlight removal based on polarization angle rotation,and obtain the highlight removal angle of each pixel by calculating the restoration to obtain the highlight removal image.Through the analysis of the polarization characteristics of the surface of transparent objects,capture images under specific lighting conditions to achieve highlight removal.Finally,the experimental verification and algorithm effect comparison of the two methods indicates they have different application scenarios.