Author Affiliations
Abstract
1 Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense, Nanjing University of Science and Technology, Nanjing 210094, China
2 e-mail: njustgel@njust.edu.cn
3 e-mail: eohj@niust.edu.cn
Non-line-of-sight (NLOS) imaging is a challenging task aimed at reconstructing objects outside the direct view of the observer. Nevertheless, traditional NLOS imaging methods typically rely on intricate and costly equipment to scan and sample the hidden object. These methods often suffer from restricted imaging resolution and require high system stability. Herein, we propose a single-shot high-resolution NLOS imaging method via chromato-axial differential correlography, which adopts low-cost continuous-wave lasers and a conventional camera. By leveraging the uncorrelated laser speckle patterns along the chromato-axis, this method can reconstruct hidden objects of diverse complexity using only one exposure measurement. The achieved background stability through single-shot acquisition, along with the inherent information redundancy in the chromato-axial differential speckles, enhances the robustness of the system against vibration and colored stain interference. This approach overcomes the limitations of conventional methods by simplifying the sampling process, improving system stability, and achieving enhanced imaging resolution using available equipment. This work serves as a valuable reference for the real-time development and practical implementation of NLOS imaging.
Photonics Research
2024, 12(1): 106
红外与激光工程
2022, 51(2): 20210889
Author Affiliations
Abstract
1 Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense, Nanjing University of Science and Technology, Nanjing 210094, China
2 e-mail: njustgel@njust.edu.cn
3 e-mail: eohj@njust.edu.cn
Imaging through scattering media is one of the hotspots in the optical field, and impressive results have been demonstrated via deep learning (DL). However, most of the DL approaches are solely data-driven methods and lack the related physics prior, which results in a limited generalization capability. In this paper, through the effective combination of the speckle-correlation theory and the DL method, we demonstrate a physics-informed learning method in scalable imaging through an unknown thin scattering media, which can achieve high reconstruction fidelity for the sparse objects by training with only one diffuser. The method can solve the inverse problem with more general applicability, which promotes that the objects with different complexity and sparsity can be reconstructed accurately through unknown scattering media, even if the diffusers have different statistical properties. This approach can also extend the field of view (FOV) of traditional speckle-correlation methods. This method gives impetus to the development of scattering imaging in practical scenes and provides an enlightening reference for using DL methods to solve optical problems.
Photonics Research
2021, 9(5): 0500B210
南京理工大学 电子工程与光电技术学院, 江苏 南京 210094
光谱测量技术在无损检测、地质勘探、农业普查等诸多方面均有广泛应用, 且随着技术的发展, 相关工艺器件近几年得到了长足的进步。在结合实际应用需求的前提下, 比较全面地介绍了光谱测量技术的发展历史, 以及近年来相关技术的研究现状和发展动态。并且从传统型、计算型、多路复用型三个角度较详细地总结了目前光谱测量的主要形式。着重介绍了包括计算层析、压缩感知、傅里叶变换、哈达码变换等多种光谱测量技术的原理及实现方法, 并分别总结了优缺点。对目前光谱测量技术中亟待解决的问题进行了分析总结, 对未来光谱测量手段的发展进行了展望。
光谱测量 压缩感知 哈达玛变换 傅里叶变换 spectral measurement compressive sensing Hadamard transform Fourier transform 红外与激光工程
2019, 48(6): 0603001
南京理工大学江苏省光谱成像与智能感知重点实验室，江苏 南京 210094
在保证分类结果清晰、准确的前提下，为了提高分类执行效率，本文基于图形处理器（graphicprocessing unit, GPU）及并行优化，提出一种基于归一化光谱向量的高光谱图像实时性非监督分类方法。利用高光谱图像的空间一致性有效提高分类精度，同时，利用归一化光谱向量简化了像元间相似性的计算公式，统一了图像内像元处理方式，并利用GPU 并行技术有效提高计算速度。首先，利用GPU 并行处理方法计算空间相邻像元间光谱向量相似性，根据高斯拟合取得安全阈值；然后利用光谱角作为像元光谱相似测度，将相似像元划为同质区；最后以同质区内各像元平均光谱向量表述同质区光谱特征，根据安全阈值合并相似的同质区完成分类。用AVIRIS 数据评估了该方法性能。本文的理论分析和实验结果显示，与现有非监督分类方法相比，该方法分类精度更高，同时，算法本身运行速度更快。
归一化光谱 并行优化 空间一致性 非监督分类 高光谱图像 normalized spectrum parallel optimization spatial coherence property unsupervised classification hyperspectral images
Author Affiliations
Abstract
1 Optical Networking and Sensing Department, NEC Laboratories America, Inc., Princeton, NJ 08540, USA
2 School of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Remotely sensing an object with light is essential for burgeoning technologies, such as autonomous vehicles. Here, an object’s rotational orientation is remotely sensed using light’s orbital angular momentum. An object is illuminated by and partially obstructs a Gaussian light beam. Using an SLM, the phase differences between the partially obstructed Gaussian light beam’s constituent OAM modes are measured analogous to Stokes polarimetry. It is shown that the phase differences are directly proportional to the object’s rotational orientation. Comparison to the use of a pixelated camera and implementation in the millimeter wave regime are discussed.
280.4788 Optical sensing and sensors 280.3420 Laser sensors 260.6042 Singular optics 080.4865 Optical vortices 140.3295 Laser beam characterization Chinese Optics Letters
2017, 15(3): 030012
1 南京理工大学电子工程与光电技术学院，江苏 南京 210094
2 南京理工大学瞬态物理国家重点实验室，江苏 南京 210094
为了增强探测器在微弱光信号条件下的成像质量，提出了一种利用哈达玛变换(Hadamard Transform，HT)实现高灵敏探测的成像方法。基于探测器噪声独立于信号，且每次测量噪声也相互独立的假设，分析了在哈达玛编码成像与经典成像中，噪声对图像信噪比的影响。推导出编码成像的信噪比提升与编码模板长度n有关，约为经典成像信噪比的sqrt(n)/2 倍。同时采用分区编码的方式，减小了高分辨率图像的编码时间。实验结果表明，与经典成像方式相比，采用分区编码的哈达玛变换成像方法明显的提高了图像的信噪比，同时可以在高分辨率图像条件下，缩短编码时间。
高灵敏成像 哈达玛变换 编码探测 图像重建 high sensitivity imaging DMD DMD Hadamard Transform encoding detection image reconstruction 红外与激光工程
2015, 44(12): 3819
南京理工大学电光学院江苏省光谱成像与智能感知重点实验室，江苏 南京 210094
针对位置已固定的双目立体装置，提出了一种基于非平行模式测距原理的双目系统光轴-光心参数标定方法，减小了光轴-光心位置误测量带来的测距误差;为解决低照度下双目立体视觉中存在的立体匹配误匹配点多、目标识别度低的问题，采取了最大熵法结合整体光强变化的阈值选取方法提取显著目标，提高了目标识别率,搭建了显著目标测距系统。结果表明：采用文中的系统标定与阈值选取方法的双目立体视觉装置在低照度下具有较高的测距精度及目标识别率。
双目测距 相机标定 目标识别 硬件实现 binocular vision ranging cameral calibration target recognition hardware implementation
Author Affiliations
Abstract
A novel high-throughput spectrometer with a wide-slit is presented. In conventional spectrometers, the slit limited the light throughput. Here, the slit is replaced with a much wider one (200 μm) to increase throughput. A beam splitter is utilized to construct a dual-path optics to measure both non-dispersed and dispersed light intensity which comes from the wide-slit. While the dispersed light intensity is result of the non-dispersed light convoluted spectrum of the source, the spectrum can be acquired by solving the inverse problem of deconvolution. Experiments show that the reconstructed spectra achieved almost the same resolution measured by traditional spectrometer, while throughput and peak signal-to-noise ratio (PSNR) are improved dramatically.
300.6190 Spectrometers 100.6640 Superresolution 100.3190 Inverse problems Chinese Optics Letters
2014, 12(4): 043001
南京理工大学 电光学院 光电技术系, 南京 210094
基于定标的三通道偏振成像系统的校正方法在对通道响应度非一致性的标定过程中操作繁琐，无法根据实际环境的变化随时校正，影响了三通道偏振成像系统的实用性。为了解决这一问题，提出了一种基于场景的三通道成像系统的校正方法。该方法基于对场景中偏振信息的统计，分离出复杂场景中无偏振性的场景分量，简单快速地修正了各通道的灰度响应差异。实验结果表明：该方法克服了通道响应度非一致性的影响，突出不同材质物体的偏振差异，使三通道偏振成像系统的成像效果接近单通道偏振成像系统水平，极大地提高了系统的实用性。
偏振 实时 非一致性 校正 polarization real time nonuniform correction
