基于Rytov积分近似的有限口径定量反演成像(特邀)  

Limited-aperture Quantitative Inverse Imaging Based on Rytov Integral Approximation(Invited)

作　　者：徐魁文 侯莎莎 邓皓千 苏江涛[1] 李文钧[1] XU Kuiwen;HOU Shasha;DENG Haoqian;SU Jiangtao;LI Wenjun(Key Laboratory of Radio Frequency Circuits and Systems,Ministry of Education,School of Electronics and Information Engineering,Hangzhou Dianzi University,Hangzhou 310018,China)

机构地区：[1]杭州电子科技大学电子信息学院射频电路与系统教育部重点实验室,杭州310018

出　　处：《光子学报》2023年第10期139-149,共11页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.62293493,61971174)。

摘　　要：提出一种适用于有限口径下高相对介电常数和大尺寸目标物体的反演方法。首先分析了低损耗介质的复折射率,通过有效折射率的计算方法得到有效折射率与介电常数关系;利用高频近似估计对比度函数,通过近似估计散射体内部散射场及其梯度对传统Rytov近似进行数学上的修正,产生无相位条件下Rytov积分近似模型,该模型可以实现定量重建高相对介电常数和大尺寸未知目标的对比度虚部。仿真结果显示有限口径下的Rytov积分近似可以对高介电常数和大尺寸目标的对比度虚部提供精确的形状重建。Currently,there are two primary approaches to addressing nonlinear electromagnetic inverse scattering problems.One method involves linearizing these issues,while the other treats them as iterative optimization problems.However,a significant challenge arises in real-world applications,where achieving uniform antenna coverage around the target proves to be exceptionally difficult.To surmount this challenge,limited aperture imaging methods have been proposed.Although limited aperture imaging provides more significant flexibility,it amplifies the nonlinearity of electromagnetic inverse scattering problems,resulting in relatively limited research on this front.This paper introduces a novel method founded on the limited aperture Rytov integral approximation for the purpose of quantitative inversion imaging of high relative permittivity and large-sized target objects.That is,the antennas are distributed only on one side of the region of interest or on some specific angles;limited aperture imaging provides greater flexibility.To begin,we introduce the concept of the phaseless Rytov approximation and meticulously analyze the complex refractive index within low-loss media.By analyzing the reflection and transmission of the incident field from the free space to the lossy media,the concept of effective refractive index is introduced and combined with Snell's theorem to solve the relationship between the effective refractive index and the actual refractive index,and the relationship between the actual refractive index and the dielectric constant is established according to the relationship between the dielectric constant and the refractive index in the low-loss media.Under the conditions of high frequency and low loss,we estimate the contrast function by taking into account the interplay between the effective refractive index,the actual refractive index,and the dielectric constant.We then employ mathematical corrections to approximate the scattered field and its gradient within the scattering object,thereby enhancing the trad

关 键 词：计算电磁学 逆散射问题 电磁成像 有限口径 Rytov积分近似 高相对介电常数 

分 类 号：O441[理学—电磁学]