Multifusion Multispectral Lightwave Polarimetric Detection Principles and Systems

The objective of this paper is to present novel detection principles based on all active multispectral polarimetric subtraction imaging principles of targets embedded in scattering media. The novelty of this contribution consists in the formation of multispectral Stokes' parameter image differences, degree of linear polarization image differences, and Mueller-matrix image differences. As a result, high-contrast high-specificity images can be obtained by removing the background from the target. Further contrast enhancement of the target with light beam steering capabilities can be obtained by doping the background surrounding the target or the target itself with high-index-of-refraction polar molecules/nanoparticles. The presented optical principles can be successfully applied to a variety of applications, such as cancer detection and treatment, molecular imaging, and development of photonics and nanophotonic devices, for a widespread group of applications, such as defense and advanced medical diagnostic and analytical devices     

偏振成像在目标探测中的应用

针对偏振度编码成像在目标探测识别中的优点,本文分析了偏振探测的消偏振机理,以及表面散射和体散射对目标偏振度的影响.利用808 nm半导体激光器照明,目标的后向散射光由卡塞格林望远镜接收,经过偏振分光棱镜成像在两个CCD上,通过一次测量获得偏振状态相互垂直的两幅图像,然后计算出目标的强度和偏振度,分别利用强度和偏振度编码成像.实验结果表明,在目标的反射率相近时,强度图像不能区分不同材料的目标,偏振度图像可以区分,融合强度和偏振度图像进行HSI伪彩色编码,可以达到目标探测、分类等目的.     

中波红外多光谱成像技术研究

多光谱成像技术结合成像和光谱测量技术,同时探测目标的光谱和几何特征,在目标识别和抑制背景杂波方面具有技术优势。研制了一套工作于中波红外波段的四通道多光谱成像系统。利用窄带滤光片和面阵探测器技术,构建了基于时序扫描的凝视成像型红外多光谱成像系统。根据红外探测器性能参数,对各个光谱通道的温度灵敏度进行了估算。在系统设计时通过合理地滤光片布局,尽量延长各个光谱通道的信号积分时间,以提高各个光谱通道温度灵敏度。利用研制的中波多光谱成像系统,对室外进行了成像,并对各个通道的成像结果进行了比较分析。     

多光谱成像系统的快速调焦方法

多光谱成像系统将光分成多个光谱通道,对不同的通道进行单独成像后合成一幅多光谱图像。不同通道的光折射率不同,造成聚焦清晰位置也不同,需要对每个通道分别调焦。为解决调焦耗时的问题,本文基于不同通道间清晰度曲线的相似性,提出一种快速的自动调焦方法。先选定一个基准通道调焦,得到清晰度曲线,对其余通道,利用清晰度曲线的相似性只需采集少量图像就能求出清晰调焦位置。实验表明,该算法能快速准确的完成对各个通道的调焦,效率明显优于已有算法。     

成像光学工程面临的光学问题

文章简单论述了现代成像光学主要领域的情况,指出非球面反射系统是发展的必然趋势。讨论了加工与检验方面的基本情况及应着重深入研究的问题。对镜坯材料也提了一点看法。     

基于IHS变换的多光谱遥感图像有损压缩算法

提出了一种有效的多光谱遥感图像有损压缩算法,该算法根据多光谱遥感图像的数据特点,将IHS变换和整数小波变换相结合进行数据压缩.采用IHS变换去除谱间相关性;采用整数小波变换去除空间相关性,依据各个子带的重要程度,用自适应阈值进行量化,并分别对量化后的数据和重要图表采用固定比特平面编码和游程编码.实验结果表明,算法在保证平均PSNR≥33dB时,获得了较高的压缩比,并且算法硬件实现简单,对内存的需求低.     

Graphitic Carbon Nitride Materials: Sensing,Imaging and Therapy

Graphitic carbon nitrides (g‐C₃N₄) are a class of 2D polymeric materials mainly composed of carbon and nitrogen atoms. g‐C₃N₄ are attracting dramatically increasing interest in the areas of sensing, imaging, and therapy, due to their unique optical and electronic properties. Here, the luminescent properties (mainly includes photoluminescence and electrochemiluminescence), and catalytic and photoelectronic properties related to sensing and therapy applications of g‐C₃N₄ materials are reviewed. Furthermore, the fabrication and advantages of sensing, imaging and therapy systems based on g‐C₃N₄ materials are summarized. Finally, the future perspectives for developing the sensing, imaging and therapy applications of the g‐C₃N₄ materials are discussed.     

Optical Imaging of Helium Interfaces

This review describes the development work done in the Low Temperature Laboratory (LTL) at the Helsinki University of Technology which has yielded high-resolution interferometric measurements on various helium interfaces at ultra low temperatures. The optical project was started in the end of 1980s and the free surface of superfluid ³He was seen for the first time ever in 1991. Additionally to the liquid/vapor interface of ³He, also the liquid/solid interface of both ⁴He and ³He has been the object of investigations. In the course of these studies several important experimental results have been obtained like the discoveries of a new surface state and two new growth mechanisms with ⁴He crystals, or the observation of a multitude of different facets on ³He crystals. The most significant findings from all these measurements are presented together with the corresponding background information and the details of the experimental setup. At the end of the review we also indicate the plans for new measurements with a faster CCD camera we hope to realize in the near future. PACS numbers: 07.60.Ly, 67.57.-z, 67.80.-s, 81.10.Aj.     

Molecular Aptamer Beacons and Their Applications in Sensing,Imaging, and Diagnostics

The ability to monitor types, concentrations, and activities of different biomolecules is essential to obtain information about the molecular processes within cells. Successful monitoring requires a sensitive and selective tool that can respond to these molecular changes. Molecular aptamer beacon (MAB) is a molecular imaging and detection tool that enables visualization of small or large molecules by combining the selectivity and sensitivity of molecular beacon and aptamer technologies. MAB design leverages structure switching and specific recognition to yield an optical on/off switch in the presence of the target. Various donor–quencher pairs such as fluorescent dyes, quantum dots, carbon‐based materials, and metallic nanoparticles have been employed in the design of MABs. In this work, the diverse biomedical applications of MAB technology are focused on. Different conjugation strategies for the energy donor–acceptor pairs are addressed, and the overall sensitivities of each detection system are discussed. The future potential of this technology in the fields of biomedical research and diagnostics is also highlighted.     

Optical Humidity Sensing Characteristics of Ag-Polyaniline Nanocomposite

Optical transmission type humidity sensor is fabricated using spin coated films of Ag-Polyaniline nanocomposite. The material is coated layer-by-layer to get films of various thicknesses (20–40 $mu{rm m}$). Relative humidity (RH) was generated by the standard two temperature method from 15 to 100%RH. The sensor shows quick response of 7 s and a fast recovery time of 50 s with better sensitivity for higher thickness. The Ag-Polyaniline nanocomposite is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible spectroscopy (UV), and Fourier Transform infrared spectroscopy (FTIR). The repeatability and cycle to cycle variation is studied and found to be encouraging.