Author Affiliations
Abstract
1 Zhejiang University, School of Physics, Zhejiang Province Key Laboratory of Quantum Technology and Device, Hangzhou, China
2 Zhejiang University, Center for Data Science, Hangzhou, China
Holographic imaging poses significant challenges when facing real-time disturbances introduced by dynamic environments. The existing deep-learning methods for holographic imaging often depend solely on the specific condition based on the given data distributions, thus hindering their generalization across multiple scenes. One critical problem is how to guarantee the alignment between any given downstream tasks and pretrained models. We analyze the physical mechanism of image degradation caused by turbulence and innovatively propose a swin transformer-based method, termed train-with-coherence-swin (TWC-Swin) transformer, which uses spatial coherence (SC) as an adaptable physical prior information to precisely align image restoration tasks in the arbitrary turbulent scene. The light-processing system (LPR) we designed enables manipulation of SC and simulation of any turbulence. Qualitative and quantitative evaluations demonstrate that the TWC-Swin method presents superiority over traditional convolution frameworks and realizes image restoration under various turbulences, which suggests its robustness, powerful generalization capabilities, and adaptability to unknown environments. Our research reveals the significance of physical prior information in the optical intersection and provides an effective solution for model-to-tasks alignment schemes, which will help to unlock the full potential of deep learning for all-weather optical imaging across terrestrial, marine, and aerial domains.
spatial coherence holographic imaging turbulence image restoration deep learning Advanced Photonics
2023, 5(6): 066003
传统的亚毫米波成像算法可以对待测目标成像, 但是, 一方面,由于成像系统的低通特性, 损失信号中的高频分量, 造成图片细节部分的缺失; 另一方面, 在信号处理过程中由于波瓣展宽, 各像点发生混叠引起模糊。针对传统算法存在的成像清晰度差和分辨率低等缺点, 提出了一种基于改进凸集投影(POCS)的亚毫米波成像超分辨率算法, 该算法利用双线性插值获得高分辨率初始图像, 并对初始图像进行迭代修正, 引入自适应校正阈值, 利用边缘强度的大小动态调整校正阈值, 从而达到精确高分辨率复原的目的。仿真实验结果表明, 该算法能够较为精确地修正图像的像素, 提高成像图片的分辨率和清晰度。
全息成像 凸集投影 超分辨率 边缘检测 holographic imaging Projections Onto Convex Sets (POCS) super-resolution edge detection
Author Affiliations
Abstract
1 Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
2 Melbourne Centre for Nanofabrication, ANFF, Clayton, VIC 3168, Australia
3 Tokyo Tech World Research Hub Initiative (WRHI), School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
Fresnel incoherent correlation holography (FINCH) is a well-established incoherent imaging technique. In FINCH, three self-interference holograms are recorded with calculated phase differences between the two interfering, differently modulated object waves and projected into a complex hologram. The object is reconstructed without the twin image and bias terms by a numerical Fresnel back propagation of the complex hologram. A modified approach to implement FINCH by a single camera shot by pre-calibrating the system involving recording of the point spread function library and reconstruction by a non-linear cross correlation has been introduced recently. The expression of the imaging characteristics from the modulation functions in original FINCH and the modified approach by pre-calibration in spatial and polarization multiplexing schemes are reviewed. The study reveals that a reconstructing function completely independent of the function of the phase mask is required for the faithful expression of the characteristics of the modulating function in image reconstruction. In the polarization multiplexing method by non-linear cross correlation, a partial expression was observed, while in the spatial multiplexing method by non-linear cross correlation, the imaging characteristics converged towards a uniform behavior.
digital holographic imaging Fresnel incoherent correlation holography holographic techniques imaging systems incoherent holography and speckle noise Chinese Optics Letters
2021, 19(2): 020501
南京理工大学 电子工程与光电技术学院,江苏 南京 210094
针对毫米波系统在二维横断面成像时,空间频率间隔上非均匀性影响成像精确度问题,提出基于截断正弦基数(sinc)函数的插值优化算法。算法取sinc函数为卷积核,对数据进行插值,相较细胞元插值法,得到的散射插值幅值更接近实际值,成像精确度更高。在此基础上,由于sinc插值需要无穷项求和,所需计算的数据量巨大,因此对插值求和项进行截断处理,对不同截断点数所成横断面像作比较,进一步优化成像质量。仿真结果验证了算法的可行性和精确性。
毫米波 全息成像 二维横断面像 sinc插值 millimeter wave holographic imaging two-dimensional cross-sectional image sinc interpolation 太赫兹科学与电子信息学报
2020, 18(6): 1035
1 清华大学工程物理系, 北京100084
2 中国民航科学技术研究院, 北京 100028
3 危爆物品扫描探测技术国家工程实验室, 北京 100084
为了在保证图像质量的前提下进一步加快毫米波全息成像的图像重建速度,提出了基于降维策略的快速反向传播重建 (DR-BP) 算法。基于亚毫米波单站式成像实验(280~320 GHz)以及多发多收正交阵列成像FEKO电磁仿真实验(70~80 GHz)对DR-BP算法进行验证。实验结果表明,DR-BP算法相比仅适用于单站式成像的快速傅里叶变换算法,重建图像边缘干扰少,相比传统的反向传播算法,重建速度大幅提升,本文实验中获得的图像质量相同时,重建速度可提升60倍。
全息成像 毫米波 图像重建 反向传播
南京理工大学电光学院探测与控制工程系, 南京 210094
针对在毫米波全息成像算法过程中像素点存在一定程度的发散、分辨清晰度不够高的问题, 提出Stolt插值优化算法, 该算法根据单元格内各个数据点与中心的距离, 取加权平均值进行插值。与传统的插值算法相比较, 该算法使得各个像素点进一步收敛, 成像更加清晰, 同时计算量不会有较大的变化。最后通过横断面仿真实验证明了该算法的有效性。
毫米波 全息成像 二维横断面像 Stolt优化算法 millimeter holographic imaging two-dimensional cross-section image Solt optimization algorithm
中国工程物理研究院电子工程研究所, 四川 绵阳 621999
建立了包含镜面反射分量的毫米波全息成像中的部分发育散斑模型。将部分发育的散斑模型与毫米波全息成像的卷积过程相结合,推导了等效散射中心个数,建立了散斑对比度与高斯粗糙面均方根高度、相关长度和成像分辨率的关系。基于近场物理光学法,对随机粗糙面的毫米波全息散斑图样进行了蒙特卡罗仿真和散斑对比度分析。结果表明,当等效散射中心个数较少时,该模型与随机积分法及仿真所估计的散斑对比度一致,优于传统模型的估计结果。
全息 毫米波全息成像 部分发育散斑 粗糙面散射 镜面反射
1 中国工程物理研究院 电子工程研究所, 四川 绵阳 621999
2 中国工程物理研究院 微系统与太赫兹研究中心, 四川 绵阳 621999
3 国防科技大学 电子科学与工程学院ATR实验室, 湖南 长沙 410073
全息雷达成像系统具有电离辐射小、穿透衣服等优点, 在人体安检等领域具有广泛的应用前景.然而, 现有系统尚存在多运动目标补偿及快速成像能力不足的问题, 限制了其在火车站等人流量大的场景中的应用.本文提出了一种基于距离多普勒概念的全息雷达成像方法, 其优点是成像速度快、运动补偿方便, 具有多运动目标快速成像的潜力.该方法利用了信号在时间采样和空间采样上的对称性, 将合成孔径雷达成像中常用的距离多普勒算法引入全息雷达成像.本文对距离多普勒全息雷达成像算法进行了推导, 通过仿真及试验, 验证了该成像方法具有多目标运动补偿及快速成像的能力.
全息成像 运动目标 距离多普勒算法 微波全息 太赫兹成像 毫米波成像 holographic imaging moving target range doppler algorithm microwave holography terahertz imaging millimeter wave imaging