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Jing C.,Science and Technology on Optical Radiation Laboratory | Zhou P.,Science and Technology on Optical Radiation Laboratory | Zhang Y.,Tianjin University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

Electrical Speckle Shearing Phase-shifting Pattern Interferometry (ESSPPI) has been used in the fields of nondestructive testing (NDT) and stress field analysis as a precise deformation measuring method. The general fixed-step phase extracting algorithms of ESSPPI, such as three-step algorithms, four-step algorithms, five-step algorithms, and their corresponding errors are analyzed. It is proved that the phase accuracy of ESSPPI with different algorithms are mainly affected by linear error of phase-shifting. Therefore the modified four-step phase-shifting extracting algorithm that isn't sensitive to linear error of phase-shifting is adopted in the paper. The filtering algorithm should be employed to reduce the influences of speckle noise and wrong data caused by errors during measurement. Then the least-squares phase-unwrapping algorithm based on fast discrete cosine transform (LPABFDCT) is adopted to search the least-squares solutions between phase difference value of adjacent pixels and unwrapped phase difference value of the pixels and the real phase distribution caused by object deformation is obtained. The Electrical Speckle Shearing Phase-shifting Pattern Interferometric images are captured with four-step phase-shifting method and the real phase distributing image is achieved with modified four-step phase-shifting extracting algorithm, denoising filter and the least-squares phase-unwrapping algorithm based on fast discrete cosine transform. It is proved with experiment results that the real phase distributing images are effective achieved by mean of combination of average filter and the least-squares phase-unwrapping algorithm based on fast discrete cosine transform. © 2016 SPIE.


Xu W.-B.,Science and Technology on Optical Radiation Laboratory | Zheng X.-B.,CAS Anhui Institute of Optics and Fine Mechanics | Li J.-W.,Science and Technology on Optical Radiation Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

Due to the new requirements of multi-site multi-time multi-satellites and high-frequency post-launch calibration, the hyperspectral post-launch cross-calibration system is developed. The system integrating global calibration-site network calibration task automatic planning software and hyperspectral cross-calibration software can efficiently execute post-launch cross-calibration and dynamic performance evaluation. The application of the hyperspectral post-launch cross-calibration system is introduced. Hyperspectral imager Hyperion is used as reference sensor and HJ-1A/HSI is used as sensor to be calibrated. The system is used to acquire the cross-calibration coefficients of all HSI bands. The average differences of all HSI bands is 6.34% when cross-calibration coefficients are compared with site-calibration coefficients. The application feasibility of the post-launch cross-calibration system is validated preliminarily. © 2017 SPIE.


Zhang Z.,Harbin Institute of Technology | Xu Y.,Science and Technology on Optical Radiation Laboratory | Wu L.,Harbin Institute of Technology | Zhang Y.,Harbin Institute of Technology | And 2 more authors.
Optics Letters | Year: 2014

We present a photon counting range-intensity image strategy based on a single-photon detector in low-light level environments. In this Letter, a composite modulation method over the pulse sequence was used for the first time, to the best of our knowledge, which combined pulse-position modulation and pulse-intensity modulation. This composite modulation method could obtain range and intensity of the detected target at the same time. Besides, angle-angle information could be provided from the scanner or detector array. Thus, a range-intensity image of the target became feasible. For demonstrating this photon counting range-intensity image strategy, a proof-of-principle laboratory system was established. In low-light level environments, a range-intensity image of multiple similar targets was obtained successfully with the range accuracy of centimeter level and intensity error of 1%. Compared with the range image, a range-intensity image could better reorganize and identify similar targets. © 2014 Optical Society of America.


Duan R.,Beihang University | Zhu X.-J.,Science and Technology on Optical Radiation Laboratory
Tuijin Jishu/Journal of Propulsion Technology | Year: 2015

A reaction mechanism involving intermediate reaction product HO2 was established for flow field simulation of afterburning of rocket plume. The mechanism was applied in CFD method to simulate the afterburning plume from an axisymmetric nozzle model at four altitudes. For comparison, a common mechanism without HO2 and a mechanism based on chemical equilibrium were used for the mentioned calculation. The results show that the hypothesis of chemical equilibrium was not appropriate for afterburning course. And compared with the common one, mechanism taking HO2 into account caused similar CO/CO2 mass fraction but higher temperature which had a maximum increasing of 100 K. As for the mass fraction of O/OH, there were huge disagreements, especially for the mass fraction of O whose value from the mechanism with HO2 various from 10% to 73% of that from the common mechanism, within the flight altitude from 5 km to 35 km. And it was concluded that HO2 was necessary to be involved into the simulation of afterburning plume. ©, 2015, Editorial Office of Journal of Propulsion Technology. All right reserved.


Sun J.,Beijing Jiaotong University | Kang Z.,Beijing Jiaotong University | Wang J.,Science and Technology on Optical Radiation Laboratory | Liu C.,Beijing Jiaotong University | Jian S.,Beijing Jiaotong University
Optics Express | Year: 2014

A novel design, two-layer low-index trench fiber with parabolicprofile core, is proposed and investigated numerically in this paper. Based on scalar FD-BPM algorithm, the excellent performance over other types of structures and great potential in mode area enlargement are demonstrated. The effective mode area of our design (D = 100μm) is approximately 890 μm2. Both the high order mode (HOM) suppression and bending resistance of our design are better than that of Multi-Trench Fiber (MTF). The mode loss ratio and effective mode area are independent on the bending radius. Due to the circular symmetry of our proposed configuration design, the bending property is not varied with the changing of bending directions. © 2014 Optical Society of America.


Wang L.,Science and Technology on Optical Radiation Laboratory | Jing C.,Science and Technology on Optical Radiation Laboratory | Zhou P.,Science and Technology on Optical Radiation Laboratory
Proceedings - 2012 4th International Conference on Multimedia and Security, MINES 2012 | Year: 2012

City management platform based on conception of smart city is a public network platform in which internet of things, cloud computing and information intelligent analysis technologies are synthetically applied. Great information resources about city management are conserved in the platform, and some parts of resources are important information related to security and benefit of country. Therefore a security system of information resources which is propitious to information safety and operation by legal users is required. Safety risks in city management platform are analyzed, and the construction of security system of information resources is designed on this basis. The resources securely sharing mechanism among multiple management domains is set up and a secure management uniform platform to network resources which is transparent to users and suitable for multi-applications is realized. © 2012 IEEE.


Wanga N.,Science and Technology on Optical Radiation Laboratory | Zhanga Y.,Science and Technology on Optical Radiation Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Main task of the infrared search and track system is analyzing and identifying targets of airspace. But first this is needed to detect all targets in infrared image. Therefore, the multi-target detection algorithms are studied and we propose an effective multi-target detection method. Firstly, an improved morphological operator is designed based on airspace background and target traits of infrared image. Background is weakened but targets are enhanced when infrared image is processed by the gray morphological filter. Then, potential targets are found by the maximum local sum algorithm. Finally, true targets are affirmed based on data association of sequence images. The infrared images got from long-wavelength infrared camera are processed with the method of the paper. Experiment results show that the method can detect targets in infrared image quickly and accurately. © 2015 SPIE.


Wang J.,Science and Technology on Optical Radiation Laboratory
Multimedia, Communication and Computing Application - Proceedings of the International Conference on Multimedia, Communication and Computing Application, MCCA 2014 | Year: 2015

Due to the larger birefringence effect in highly nonlinear fibers (HNLF), it is able to observe a higher scattering efficiency of GAWBS. In this paper, we theoretically analyze the polarized and depolarized GAWBS induced by transverse acoustic mode in HNLF for the first time. We deduce the displacement function and scattering efficiency of GAWBS starting from the vibration function of transverse mode. The frequency of peak scattering efficiency in HNLF is higher than single-mode fiber (SMF-28), which appears at the frequency of nearly 470 MHz. The bandwidth of scattering in HNLF is about three times than that in SMF-28. The scattering efficiency of polarized GAWBS induced by R0m mode is bigger than that by TR2m mode, which is almost vanished at higher frequency. © 2015 Taylor & Francis Group, London.


Gao Y.,Beijing Jiaotong University | Ren G.,Beijing Jiaotong University | Zhu B.,Beijing Jiaotong University | Wang J.,Science and Technology on Optical Radiation Laboratory | Jian S.,Beijing Jiaotong University
Optics Letters | Year: 2014

We propose in this Letter a single-mode graphene-coated nanowire surface plasmon waveguide. The single-mode condition and modal cutoff wavelength of high order modes are derived from an analytic model and confirmed by numerical simulation. The mode number diagram of the proposed waveguide in the wavelength-radius space is also demonstrated. By changing the Fermi level of graphene, the performance of the proposed waveguide could be tuned flexibly, offering potential application in tunable nanophotonic devices. © 2014 Optical Society of America


Kang Z.,Beijing Jiaotong University | Wen X.,Beijing Jiaotong University | Li C.,Beijing Jiaotong University | Sun J.,Beijing Jiaotong University | And 2 more authors.
Applied Optics | Year: 2014

A novel all-fiber sensing configuration for simultaneous measurements of temperature and strain based on the up-taper Mach-Zehnder interferometer (MZI) with an in-line embedded fiber Bragg grating (FBG) is proposed and experimentally demonstrated. This configuration consists of two up-tapers fabricated by an excessive fusion splicing method and a short segment of inscribed FBG. Due to the different responses of the up-taper MZI and the FBG to the uniform variation of temperature and strain, the simultaneous measurement for these two variables could be achieved by real-time monitoring the transmission spectrum. For 0.01 nm wavelength resolution, a resolution of 0.311° C in temperature can be achieved, and the average strain resolution is 10.07 ìa˚. © 2014 Optical Society of America.

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