无偏振片液晶透镜深度估计  

Depth Estimation Using Polarizer-Free Liquid Crystal Lens

作　　者：赖文杰 刘志强 孙涛 胡晓 Lai Wenjie;Liu Zhiqiang;Sun Tao;Hu Xiao(School of Optoelectronic Science and Engineering,University of Electronic Science and Technology of China,Chengdu 610000,Sichuan,China;Armored Forces Research Institute,Army Research Academy,Beijing 100072,China)

机构地区：[1]电子科技大学光电科学与工程学院,四川成都610000 [2]陆军研究院装甲兵研究所,北京100072

出　　处：《光学学报》2023年第14期161-172,共12页Acta Optica Sinica

基　　金：四川省自然科学基金(2022NSFSC1839)。

摘　　要：设计了一种无偏振片液晶透镜的离焦深度测量(DFD)方法。分别建立液晶透镜成像下的o光和e光的高斯模糊退化模型,将其加权求和得到自然光在液晶透镜成像下的模糊退化模型,求取自然光和e光下深度估计对噪声的偏导,并进行数值仿真,结果表明,自然光模型比e光模型抗干扰能力更强,小模糊光斑比大模糊光斑抗干扰能力更强。在无偏模糊均衡滤波器(UDE)算法的基础上,利用导向滤波对偏差进行滤波,并对置信度模型进行修正,引入实例分割对估计结果进行优化。搭建了放大率恒定的液晶透镜光学成像系统,实现了自然光条件下利用液晶透镜的深度测量。实验结果表明,本文方案和e光条件下UDE方法相比,均方根误差降低了56%。Objective Visionbased depth estimation is an important research direction of computer vision,which is of great significance to threedimensional(3D)reconstruction,semantic segmentation,navigation,etc.The monocular depth estimation scheme has the advantages of low cost and easy installation,which cannot be realized by binocular stereo vision and lidar,and it has received more and more attention in recent years.There is a strong correlation between the outoffocus image degradation and the location of the object being photographed,which can be used as a source of information for monocular depth estimation.Traditional depth estimation algorithms based on depth from defocus(DFD)use mechanical zoom,which results in misaligned images.In addition,mechanical zoom has certain disadvantages in terms of response speed,accuracy,and service life.To avoid these problems,Ye et al.used the liquid crystal lens as the zoom device to implement the DFD algorithm.Liquid crystal lens imaging requires the use of polarizers to filter ordinary light(olight),so as to reduce the incoming light by half.Ye et al.proposed a liquid crystal lens imaging technology without polarizers.They collected two images:one with voltage applied to the liquid crystal lens,and the other without voltage.They used the image without voltage to obtain the olight component and subtracted the olight component from the image taken under voltage to obtain an extraordinary light(elight)image.The nonpolarizer liquid crystal lens imaging scheme requires the collection of at least two images for a single focus setting.If this scheme is employed for DFD,at least four images need to be collected.However,the use of image enhancement techniques such as image filtering to suppress noise can result in the loss of valuable image information.In this work,we propose a polarizerfree scheme that is wellsuited for DFD.This scheme eliminates the need for collecting additional images and requires only the capture of two outoffocus images by using a polarizerfree liquid crystal lens.We

关 键 词：机器视觉 无偏振片 液晶透镜 失焦深度估计 无偏滤波器 实例分割 

分 类 号：O436[机械工程—光学工程]