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A liquid crystal thermography calibration with true color image processing

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Chinese Optics Letters 2009年第9期7卷 795-797页

作者：饶宇臧述升黄名海 Institute of Turbomachinery School of Mechanical and Power EngineeringShanghai Jiao Tong University

Liquid crystal thermography is a high-resolution, non-intrusive optical technique for full-field temperature measurement. We present the detailed calibration data for the thermochromic liquid crystal （TLC） with a useful range of 41-60 ℃. The calibration is done with true color image processing by using an isothermal calibrator. The hue-temperature curve of the TLC is obtained, and the measurement uncertainty is analyzed. Combined with the image noise reduction technique of a 5×5 median filter, the measurement accuracy of the liquid crystal thermography can be significantly improved by approximately 57.1%.

关键词： Calibration Dendrites (metallography) Imaging systems Liquid crystals optical data processing Remote sensing Thermography (imaging) Thermography (temperature measurement) Uncertainty analysis

Accurate analysis of ellipsometric data for thick transparent films

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Chinese Optics Letters 2011年第5期9卷 81-84页

作者：赵源盛明裕郑玉祥陈良尧 Department of optical Science and Engineering Fudan University Department of optical Electronics Information Engineering Shanghai Second Polytechnic University Department of Electronics Information Engineering Shanghai Business School

Using e-beam evaporation, the ellipsometric parameters of thick transparent films are studied with the modified analysis method for the SiO 2 film samples deposited onto the Si substrate. The ellipsometric parameters are measured at the incidence angles changing from 50 to 70 and in the 3–4.5 eV photon energy range. The error in the conventional method can be significantly reduced by the modified ellipsometric method considering the spatial effect to show good agreement between the theoretical and experimental results. The new method presented in this letter can be applied to other optical measurement of the periodic or non-periodic film structures.

关键词： optical data processing optical films Periodic structures Silicon compounds

On the stability of multicast flow aggregation in IP over optical network for IPTV delivery

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Chinese Optics Letters 2008年第8期6卷 553-557页

作者：罗萱金耀辉曾庆济孙卫强郭薇胡卫生 State Key Lab of Advanced optical Communication Systems and Networks Shanghai Jiao Tong University

The stable multicast flow aggregation （MFA） problem in internet protocol （IP） over optical network under the dynamical scenario is studied. Given an optical network topology, there is a set of head ends and access touters attached to the optical network, in which each head end can provide a set of programs （IP multicasting flows） and each access router requests a set of programs, we find a set of stable light-trees to accommodate the optimally aggregated multicast IP flows if the requests of access touters changed dynamically. We introduce a program correlation matrix to describe the preference of end users＇ requests. As the original MFA problem is NP-complete, a heuristic approach, named most correlated program first （MCPF）, is presented and compared with the extended least tree first （ELTF） algorithm which is topology- aware. Simulation results show that MCPF can achieve better performance than ELTF in terms of stability with negligible increment of network resource usage.

关键词： Agglomeration Electric network topology Fiber optic networks Heuristic algorithms Heuristic programming Internet Mobile telecommunication systems Multicasting Nuclear propulsion optical data processing optical materials Routers Topology Trees (mathematics)

Phase-controlled gain, phase shift, and group velocity using a room-temperature active-Raman-gain medium

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Chinese Optics Letters 2009年第7期7卷 549-552页

作者：杭超黄国翔 State Key Laboratory of Precision Spectroscopy and Department of Physics East China Normal University

A four-level tripod active-Raman-gain scheme is analyzed for obtaining phase-controlled gain, phase shift, and group velocity at room temperature. The scheme can be used to eliminate significant probe field atten- uation or distortion which is unavoidable in the scheme based on electromagnetically induced transparency. It is shown that the intensity gain, phase shift, and group velocity of a probe field can be simultaneously manipulated by changing the relative phase of two pump fields. The scheme is also different from that proposed recently by Deng et al. where a probe-field gain always exists. New features of the scheme presented here raise the possibility of designing rapidly responding optical switches and gates for optical information processing.

关键词： Fluorine containing polymers Light velocity optical data processing Phase shift Probes

Properties of the 3D photonic nanojet based on the refractive index of surroundings

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Chinese Optics Letters 2010年第7期8卷 706-708页

作者：丁红星戴丽莉闫长春 Department of Physics Lianyungang Teachers College Department of Applied Physics Nanjing University of Science and Technology School of Physics and Electronic Engineering Xuzhou Normal University

We exhibit a three-dimensional （3D） photonic nanojet based on a dielectric microsphere irradiated by a plane wave with the finite-difference time-domain （FDTD） method. We investigate the influence of the refractive index of the surrounding on the properties of the nanojet by simulating the electric field distributions in it. The simulation results show that, by optimally choosing the size of the sphere and the ratio of the refractive indices of the sphere and the surrounding, the focus point can occur just on the surface of the sphere even if the refractive index of the surrounding is changed. Additionally, the peak amplitude of the nanojet increases with increasing the refractive index of the surrounding. However, the decay length and the jet width of the nanojet decrease simultaneously. These effects may have potential applications in observation or manipulation of nano-objects such as antibodies in biology. In nanojet-enabled optical data storage, the photonic nanojet may be also helpful for improving data-storage capacities and retrieval speed by controlling the field amplitude, the decay length, and jet width of the nanojet.

关键词： Electric fields Electric properties Finite difference time domain method Light refraction optical data processing optical data storage Organic polymers Refractive index Refractometers Three dimensional

Close-range optical measurement of aircraft's 3D attitude and accuracy evaluation

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Chinese Optics Letters 2008年第8期6卷 564-567页

作者：李喆丁振良袁峰 Department of Automatic Measurement and Control Harbin Institute of Technology

A new screen-spot imaging method based on optical measurement is proposed, which is applicable to the close-range measurement of aircraft＇s three-dimensional （3D） attitude parameters. Laser tracker is used to finish the global calibrations of the high-speed cameras and the fixed screens on test site, as well as to establish media-coordinate-frames among various coordinate systems. The laser cooperation object mounted on the aircraft surface projects laser beams on the screens and the high-speed cameras synchronously record the light-spots＇ position changing with aircraft attitude. The recorded image sequences are used to compute the aircraft attitude parameters. Based on the matrix analysis, the error sources of the measurement accuracy are analyzed, and the maximum relative error of this mathematical model is estimated. The experimental result shows that this method effectively makes the change of aircraft position distinguishable, and the error of this method is no more than 3′ while the rotation angles of three axes are within a certain range.

关键词： Aircraft Cameras High speed cameras Lasers Mathematical models Measurements optical data processing optical variables measurement Speed

Average modulation transfer function of line-array fiber-optic image bundles

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Chinese Optics Letters 2004年第8期2卷 453-455页

作者：王慧向阳禹秉熙 State Key Lab for Applied Optics Changchun Institute of OpticsFine Mechanics and Physics Chinese Academy of Sciences Changchun 130033 Graduate School of the Chinese Academy of Sciences Beijing 100039 Aviation University of Air Force Changchun 130022 State Key Lab for Applied Optics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun 130033 State Key Lab for Applied Optics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun 130033he image quality evaluation in fiber-optic image bundles was addressed by the modulation transfer function (MTF). With the definition of the contrast transfer function (CTF) the MTF model of line-array fiber-optic image bundles was established and analyzed numerically. The average MTF was carefully evaluated by considering the influence of phase match on the MTF between input pattern and fiber-optic image bundles. In this paper the average MTF is mean arithmetical value on the MTFs of eight different phases. The results show that for certain fiber diameter and spatial frequency the relationship between the core diameter and the average MTF is inverse proportion for certain fiber cladding thickness the relationship between the core diameter and the average MTF is also inverse proportion. And at Nyquist frequencv. the MTF value is near 0.5.

The image quality evaluation in fiber-optic image bundles was addressed by the modulation transfer function (MTF). With the definition of the contrast transfer function (CTF), the MTF model of line-array fiber-optic image bundles was established and analyzed numerically. The average MTF was carefully evaluated by considering the influence of phase match on the MTF between input pattern and fiber-optic image bundles. In this paper, the average MTF is mean arithmetical value on the MTFs of eight different phases. The results show that, for certain fiber diameter and spatial frequency, the relationship between the core diameter and the average MTF is inverse proportion; for certain fiber cladding thickness, the relationship between the core diameter and the average MTF is also inverse proportion. And at Nyquist frequencv. the MTF value is near 0.5.

关键词： Fiber optics Image quality Imaging systems optical data processing

optical Image Encryption Based on Mixed Chaotic Maps and Single-Shot Digital Holography

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Transactions of Tianjin University 2017年第2期23卷 184-191页

作者： Yonggang Su Chen Tang Xia Chen Biyuan Li Wenjun Xu Zhenkun Lei School of Electrical and Information Engineering Tianjin University Tianjin 300072 China Science and Technology on Electro-optical Information Security Control Laboratory Tianjin 300308 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024China

Random phase masks play a key role in optical image encryption schemes based on double random phase technique. In this paper, a mixed chaotic method is proposed, which can efficiently solve some weaknesses that one-dimensional (1-D) single chaotic maps encounter to generate random phase masks. Based on the chaotic random phase masks, optical image encryption and decryption are realized with a single-shot digital holographic technique. In the proposed encryption scheme, the initial value and parameters of mixed chaotic maps serve as secret keys, which is convenient for the key management and transmission. Moreover, it also possesses high resistance against statistical attack, brute-force attack, noise attack and shear attack. Simulation results and security analysis verify the validity and security of the proposed encryption scheme. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

关键词： Chaotic systems Geometrical optics Holography Image processing Lyapunov methods optical data processing

Consistency proof of two denoising methods and the parameter selection of PDE f iltering method for ESPI

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Chinese Optics Letters 2013年第12期11卷 33-38页

作者：肖志涛袁泉张芳吴骏耿磊徐振北习江涛 School of Electronics and Information Engineering Tianjin Polytechnic University School of Electrical Computerand Telecommunications EngineeringUniversity of Wollongong

Electronic speckle pattern interferometry （ESPI） is a nondestructive, whole-field optical measurement technique. The removal of speckle noise is fundamental to extract measurement information accurately. In this letter, two filtering methods based on the oriented feature of ESPI fringes, i.e., the second-order oriented partial differential equation （SOOPDE） and oriented, regularized quadratic-cost function filtering methods, are first proven to be consistent. An important question in solving partial differential equation, i.e., how to select suitable parameters in an adaptive manner, is then discussed. The computer-simulated and experimentally obtained ESPI fringe patterns and phase map are processed by the SOOPDE filtering model with adaptive selective parameters. The qualitative and quantitative analyses demonstrate that the parameters selected by the adaptive method are effective and suitable for the SOOPDE filtering model.

关键词： Computer simulation Interferometry optical data processing Speckle