电视跟踪系统中的全视场捕获

本文介绍一种用于电视跟踪系统的全视场捕获模块,在背景较为单调的情况下,它可以在一个电视场的时间内,在全视场范围内自动捕获目标,该模块还具有波门跟踪功能。文中给出了模块的具体实现及外场试验结果。     

129I加速器质谱分析研究

通过对129I加速器质谱(AMS)分析中影响敏度和准确度各种参数的研究,如靶电极制备、压样、靶样中辅助介质（Matrix）的选择及使用比例等,优化了用于3 MV加速器质谱仪的SO-110型离子源的条件参数,确定129I-AMS测量的最佳靶电极材料为Cu,最佳的辅助介质为Nb粉末,Nb与AgI样品的最佳体积比为3∶1。在此条件下可以获得稳定且持续的I-束流进行测量129I/127I原子比值,实验测得西安加速器质谱仪的129I/127I本底值为1.5210-14。     

人造复眼成像系统研究的新进展

人造复眼成像系统具有体积小、功耗低、视角范围广等优点，是一种应用前景非常广阔的光成像系统。综述了人造复眼成像系统的研究背景及最新的研究进展，其中包宿基于不同仿生设计理念的各种新型人造复眼结构以及能够实现诸如彩色成像、指纹识别、全视角成像等新功能的实验系统；展望了人造复眼成像系统今后的研究方向。     

S-CO2布雷顿循环转化效率分析

以超临界二氧化碳简单回热型布雷顿循环为研究对象,以核电站为应用背景,详细论述了系统循环模型与关键器部件的效率模型建立方法,并利用该模型初步分析了各类工程因素对布雷顿循环效率、系统体积的影响,分析结果表明,循环效率、系统体积对温度、压力、涡轮机械效率、回热器等参数的敏感性存在较大差异,其中增加透平入口温度对缩减系统总体积最为有效,需要建立完善的系统分析模型以进行S-CO₂系统的优化设计。     

衍射光学在无人机姿态控制中的应用

CCD星敏感器是无人飞机等航空航天器姿态控制的关键设备,其工作谱段很宽,跨可见光至近红外光光谱,且对系统的体积有特殊的要求,从而可满足飞行器的小空间体积的要求。针对一实际用于无人飞机上的系统的要求(焦距为60～100mm,F/1.3～F/2,谱段范围为0.48～0.85μm,视场为80°～100°),提出了使用折衍混合的新型光学系统,在较宽谱段内消除了色差,并校正了其它像差。从设计结果可以看出,系统可满足最终的使用要求。     

光子图象的X2拟合信号检验

本文首次应用以微通道板象增强器为核心器件的超高灵敏度光电成象系统获得了活体昆明鼠的超微弱生物发光图象,并用统计理论研究了光子图象中的信号和背景分布,提出用斯米尔诺夫检验判别图象中有无信号的方法,以及用X²准则拟合实际图象中的信号区和背景区分布,并根据得到的统计估计值对光子图象进行检验,上述光子图象中的拟合方法以及斯米尔诺夫判据检验到了图象中的信号,验证了实际获得的光子图象中存在发光信号的结论。     

国家自然科学基金(40776059)资助

为了克服水下探测中后向散射光背景噪音的影响,提出了非均匀光场水下探测方法,推导得出非均匀光场的照度分布函数与接收口径、目标与接收器的距离以及海水的体积衰减系数几个因素有关.通过搭建集束光水下图像系统,对其产生的非均匀光场的分布特性和水下探测特性进行了水池实验.观测结果为,在0.6倍能见度下,可分辨1 mm细节,在1倍能见度时,可分辨目标轮廓,在1.5倍能见度时,可探测到目标.结果证明,该系统具有宽视角、全景深、图像清晰度高等特点.     

荧光褪色效应与拉曼光谱基线干扰消除

荧光是直接测定的拉曼光谱中背景的最主要来源,需要采用真实、准确的方法消除,以得到纯净的拉曼响应。基线拟合消除和查找荧光贡献扣除是解决背景问题的两条思路,目前多采用基线拟合方法,其优点是满足用户“视觉”要求,无需额外硬件,但并非机理或实质上的解释,因而难以保证数据的真实性与合理性;查找荧光的方法,更为真实,但是目前提出的方法,需要增加光源等额外设计和成本。另外,在实验方法上,也有采用消荧光剂和长时间照射漂白的,存在操作繁琐、效率低等不足。利用稳定体系中拉曼和荧光的时间差异解决体系中荧光问题。在微小的时间段内,例如几个毫秒,激发光不会导致体系性质发生显著变化,荧光具有寿命周期,会随激发时间延长强度下降的“褪色”,“褪色”的强度差异可以被认为是整体荧光的一个微元;与此同时,由于体系组成未发生显著变化,拉曼光对于短时间照射可以保持稳定。利用此差异可以区分出混合信号中的荧光和拉曼光。根据该原理,提出了荧光褪色差分法(FBDA),实现拉曼光谱的背景校正。方法的主要步骤：测量微小时刻内的多张直接拉曼光谱,求取系列光谱的差分,对差分值作高频滤波降噪,可获得荧光强度微元;然后,多个荧光微元平均归一化后,得到荧光强度单元。以拉曼光谱2 000～2 500 cm-1的静默区,即通常不会出现拉曼信号的频段为基准,对荧光单元作逆差分,逆差分累计值与原始光谱在此频段一致时,得到整体荧光响应;最终,从原始光谱中扣除荧光成分,完成背景扣除和基线校正。以盐酸二甲双胍片的拉曼测量为例,说明和讲解了所提出的原理和方法,验证方法的有效性。与目前效果较好的基线校正方法(不对称最小二乘和自适应迭代再加权惩罚偏最小二乘)进行了对比,表明FBDA方法更为客观真实,FBDA的另一个优势是不需要额外的设计和成本,所有数据都是在现有设备直接采集和完成。需要说明的是,微小时刻光谱差异的要求,可以确保FBDA光谱实时性,长时间的光谱差异,将会影响结果的准确性;另外,对于光化学反应体系和其他非荧光引起的复杂背景,FBDA的适用性有待改善。     

Engineering of SERS Substrates Based on Noble Metal Nanomaterials for Chemical and Biomedical Applications

Abstract

Surface-enhanced Raman scattering (SERS) has attracted great interest due to its remarkable enhancement, excellent sensitivity, and the “fingerprinting” ability to produce distinct spectra for detecting various molecules. Noble metal nanomaterials have usually been employed as SERS-active substrates because of their strong SERS enhancement originated from their unique surface plasmon resonance (SPR) properties. Because the SPR property depends on metal material's size, shape, morphology, arrangement, and dielectric environment around metal nanostructures, the key to wider applications of SERS technique is to develop plasmon-resonant structures with novel geometries to enhance Raman signals and to control the periodic ordering of these structures over a large area to obtain reproducible Raman enhancement. This review presents a general view on the theory background of SERS effect and several basic concepts and focuses on recent progress in engineering metallic nanostructures with various morphologies using versatile methods for improving SERS properties. Their potential applications in the field of chemical detection and biological sensing are overviewed.     

A System for Registering Shadow Images of Rapid Processes in the UV Spectral Range under the Conditions of Intense Background Illumination

A system is presented for registering shadow images obtained from dense pulsed plasma with a high background illumination level, wherein an LGI-21 molecular nitrogen laser is used as an illuminator (laser pulse power 12 µW, duration 20 ns), and a modified Canon EOS 1000D camera is used as a registering unit. A micropinch discharge such as a high-current low-inductance vacuum spark (HCLIVS) has been used as the plasma object under investigation.     

Analysis of telescope array receivers for deep-space inter-planetary optical communication link between Earth and Mars

Optical communication technology shows promising prospects to fulfill the large bandwidth communication requirements of future deep-space exploration missions that are launched by NASA and various other international space agencies. At Earth, a telescope with a large aperture diameter is required to capture very weak optical signals that are transmitted from distant planets and to support large bandwidth communication link. A single large telescope has the limitations of cost, single point failure in case of malfunction, difficulty in manufacturing high quality optics, maintenance, and trouble in providing communication operations when transmitting spacecraft is close to the Sun. An array of relatively smaller-sized telescopes electrically connected to form an aggregate aperture area equivalent to a single large telescope is a viable alternative to a monolithic gigantic aperture. In this paper, we present the design concept and analysis of telescope array receivers for an optical communication link between Earth and Mars. Pulse-position modulation (PPM) is used at the transmitter end and photon-counting detectors along with the direct-detection technique are employed at each telescope element in the array. We also present the optimization of various system parameters, such as detector size (i.e., receiver field of view), PPM slot width, and the PPM order M, to mitigate the atmospheric turbulence and background noise effects, and to maximize the communication system performance. The performance of different array architectures is evaluated through analytical techniques and Monte-Carlo simulations for a broad range of operational scenarios, such as, Earth-Mars conjunction, Earth-Mars opposition, and different background and turbulence conditions. It is shown that the performance of the telescope array-based receiver is equivalent to a single large telescope; and as compared to current RF technology, telescope array-based optical receivers can provide several orders of magnitude greater data rates for deep-space communication with Mars.     

Features of the manifestation of a stop band in the spectrum of light diffracted at a glass-opal interface

The diffraction of light passing through a glass plate coated by an artificial opal film has been analyzed. It has been shown that the stop band of a photonic crystal is manifested against the background of the unchanged spectrum of reflected and refracted Bragg waves. The position of this stop band can be changed under a small change in the concentration of a number of substances filling the photonic crystal. The application of such an optical system as an optical chemical sensor has been demonstrated.     

不同紫外波段激发生物气溶胶荧光雷达系统性能分析

基于激光诱导生物荧光技术,分别采用紫外355nm和266nm激光作为激发光源,构建生物气溶胶荧光雷达监测系统模型.综合考虑不同激发波段,臭氧吸收以及太阳背景光等因素对激光雷达荧光探测效果的影响,对系统性能进行数值仿真分析.仿真结果表明,在四倍频266nm紫外波段的激光激发下,系统受地表臭氧的影响,白天的有效探测距离非常有限;在系统信噪比为10(SNR=10),臭氧浓度为50μg/L时,最大探测距离仅为300m;而夜间情况下,太阳背景光影响减弱,探测距离约为450m.三倍频355nm激发时,臭氧对系统的探测性能影响较小,夜间探测距离可达750m;白天太阳背景光对355nm的系统影响较大,在相同0.5mrad接收视场角下,其有效探测距离约为330m.为减少白天背景光的影响,将望远镜接收视场角压缩到0.3mrad,同时选用50nm带宽的滤光片,此时系统的探测距离为480m.由于355nm波段的激发荧光受白天太阳背景光的影响较大,在进行夜间探测时才可获得较好的效果;而266nm的激发波段可以很好的抑制背景光影响,能够实现对生物气溶胶的白天有效探测.     

均匀背景中的动态小目标光谱数据获取方法研究

光谱是一种可以表征物质特性的光学信息,利用光谱成像仪可以获取处于视场范围内的物质的光谱图像,成熟的光谱成像技术均需要通过多次采集才能够获取完整的光谱图像数据立方体,相应系统的时间分辨率比较低,不适用于动态目标的光谱获取。快照式光谱成像在动态目标光谱成像方面具有较大的优势,其中编码孔径快照光谱成像技术是一种将压缩感知计算方法融入到光谱成像过程和图谱重构过程中的光谱成像技术,在采样过程中完成数据压缩,具有高通量优势,可以利用单次曝光的混叠数据,重构出目标光谱数据立方体,实现快照式成像,使得对动态的目标进行监测成为可能。实现监测需要目标的信息满足稀疏性的假设,实际目标很难满足这样的条件,重构误差比较大,不利于对动态的小目标进行监测和识别。针对均匀背景中动态小目标的光谱数据获取,提出一种双色散通道的编码孔径光谱成像方法,系统由两个通道组成,每个通道均包含一个光谱仪,其色散方向互相垂直,并共用一个前置望远镜系统和编码孔径。该系统可以实时观测均匀背景区域中的动态小目标。由于两个通道的色散方向互相垂直,可以从背景中分离出小目标的位置和相对应的编码。假设目标出现在视场中前后,背景的辐射特性变化很小,利用目标出现前的数据计算出背景光谱;目标出现后,通过帧间差分运算,消除背景辐射的影响,提取出目标位置对应色散区域中数据,利用约束最小二乘算法,重构运动小目标的光谱数据立方体。进行光谱数据重构,进行背景光谱补偿后,获得完整的动态小目标光谱数据。文章对成像过程建立了数学模型,并对重构方法进行了仿真验证,结合编码孔径的统计特征,使目标随机出现在不同的位置,统计重构光谱的峰值信噪比概率分布,并调整目标尺寸,分析目标尺寸对重构精度的影响,最后与编码孔径成像系统的两步软阈值迭代算法重构结果进行了对比。结果表明,这种方法在均匀背景中,采用随机编码矩阵进行编码,目标尺寸小于5×5个像元时,相对于编码孔径成像系统,提高了目标的信息重构精度和概率,并且极大的减小了运算量,可以实现对运动目标的实时监测。     

Cloaking an acoustic sensor with single-negative materials

In this review, a brief introduction is given to the development of acoustic superlens cloaks that allow the cloaked object to receive signals while its presence is not sensed by the surrounding, which can be regarded as “cloaking an acoustic sensor”. Remarkably, the designed cloak consists of single-negative materials with parameters independent of the background medium or the sensor system, which is proven to be a magnifying superlens. This has facilitated significantly the design and fabrication of acoustic cloaks that generally require double-negative materials with customized parameters. Such innovative design has then been simplified further as a multi-layered structure comprising of two alternately arranged complementary media with homogeneous isotropic single-negative materials. Based on this, a scattering analyses method is developed for the numerical simulation of such multi-layered cloak structures, which may serve as an efficient approach for the investigation on such devices.     

Microscopic scattering imaging measurement and digital evaluation system of defects for fine optical surface

According to ISO10110-7 and the engineering standards of Inertial Confinement Fusion (ICF), this paper presents a microscopic scattering imaging and analyzing system which allows one to automatically evaluate defects in random distributions and shapes on the surface of fine optical components of large aperture. The annularly disposed multi-beam fiber light sources illuminate the target surface with a special angle. The image, which has bright defects on black background, is suitable for digital image processing. With XY-scanning system, the defect information of full aperture can be obtained by stitching the sub-aperture image array, according to the algorithms of template matching. The full aperture image is divided into N × N sub-apertures, each of which has view field of approximate 3 mm × 4 mm. Image processing software for image recognition has been established using mathematical morphology with high computing efficiency and friendly graphics user interface. A group of standard reticules fabricated by binary optics can scale defects for calibration. As a result the lateral resolution of the system is better than sub-micrometer while the total view field can be hundreds of millimeters. The comparison quantitative data results between the experiment and standard demonstrate the system is competent for the digital evaluation of defect characterization of fine optical surfaces, especially for the ones with large aperture.     

A Physical Approach to Tsirelson’s Problem

Tsirelson’s problem deals with how to model separate measurements in quantum mechanics. In addition to its theoretical importance, the resolution of Tsirelson’s problem could have great consequences for device independent quantum key distribution and certified randomness. Unfortunately, understanding present literature on the subject requires a heavy mathematical background. In this paper, we introduce quansality, a new theoretical concept that allows to reinterpret Tsirelson’s problem from a foundational point of view. Using quansality as a guide, we recover all known results on Tsirelson’s problem in a clear and intuitive way.     

What Is Temperature? Modern Outlook on the Concept of Temperature

The meaning and evolution of the notion of “temperature” (which is a key concept for the condensed and gaseous matter theories) are addressed from different points of view. The concept of temperature has turned out to be much more fundamental than conventionally thought. In particular, the temperature may be introduced for systems built of a “small” number of particles and particles at rest. The Kelvin temperature scale may be introduced into quantum and relativistic physics due to the fact that the efficiency of the quantum and relativistic Carnot cycles coincides with that of the classical one. The relation of temperature with the metrics of the configurational space describing the behavior of systems built from non-interacting particles is demonstrated. The role of temperature in constituting inertia and gravity forces treated as entropy forces is addressed. The Landauer principle asserts that the temperature of a system is the only physical value defining the energy cost of the isothermal erasure of a single bit of information. The fundamental role of the temperature of the cosmic microwave background in modern cosmology is discussed. The range of problems and controversies related to the negative absolute temperature is treated.     

Explicit two-loop calculation of decoupling in unbroken gauge theories with fermions

Unbroken gauge theories containing light as well as heavy fermions are considered in the limit of the mass of the heavy fermions tending to infinity. The effective coupling constant of the decoupled low-energy theory thus obtained, has been calculated up to two-loop level using the light particle irreducible vertex function and the background field formalism. In addition, to simplify the computation, a background field gauge-fixing term has been used, because in such a gauge the effective coupling constant can be calculated from a two-point function only. Our analysis reveals that in the non-abelian theory, the simple algorithm proposed by Ovrut and Schnitzer for computing the effective coupling constant up to the two-loop level is valid only in the α = 0 or α = ?3 background field gauge. A general procedure correct for all values of α is described.     

Infrared (IR) image synthesis method of IR real background and modeled IR target

An infrared (IR) image synthesis method is proposed for the synthesis of a real IR background and modeled IR target, used as IR signatures, as well as a band-transformation between short wave IR (SWIR), middle wave IR (MWIR), and long wave IR (LWIR) in an IR imaging system simulation. IR target images are created by the RadThermIR software, an IR signature prediction software. Individual radiances for IR signatures, corresponding to the max/min temperatures of a real IR background and modeled IR target image, are calculated with Planck’s law. First, an IR background of an arbitrary wavelength band is transformed to one of the other wavelength bands with the temperature-radiance characteristics. And then, after adjusting the gray levels of the arbitrary IR target signatures based on their radiances for the wavelength band of the transformed IR background, these IR target and background signatures can be synthesized as one image for a specific wavelength band. The experimental results show that the modeled IR target images, such as a modeled helicopter and F16, can be synthesized on the IR background images of three IR wavelength bands. And we confirmed that IR background images of the three IR wavelength bands can diversely be synthesized with the modeled IR targets as the setting temperature of the target and background, the target distance, and the field of view (FOV) arbitrarily.