Xiang-dong Qi

Chinese Academy of Sciences, Peping, Beijing, China

Are you Xiang-dong Qi?

Claim your profile

Publications (11)6.81 Total impact

  • Xiang-dong Qi · Da-wei Liu · Jin-lin Wang
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper addresses the problem of large scale content-based video retrieval with relevance feedback. We analyze the common methods which leverage local feature detectors to extract feature descriptors from video collections and perform multi-level matching after indexing and retrieval of feature vectors. Instead of learning similarity-preserving codes, an approach of relevance feedback in a light-weight way is proposed. A relevance model is proposed to merge semantic similarity with the original distance matching at descriptor level. By learning several weights using canonical correlation analysis (CCA), the resulting candidate list of similar videos changes according to relevance feedback. Finally, we demonstrate the improvement of the proposed method by experiments on a standard real world dataset.
    No preview · Article · Oct 2013 · Proceedings of SPIE - The International Society for Optical Engineering
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present paper analyzed the influence of the pinhole diameter, grating parameters, CCD pixel size, prism parameters, system aberrations and found that the first three are the main factors, and then deduced the mutual restraint relationship among them. On this basis, a portable high-resolution echelle spectrograph was designed. Applying this design, aberration was fully corrected and spectral resolution achieved the demand. With the Hg lamp calibrated and restored, the actual resolution gets up to 0.038 nm which is significantly better than target (0.05@200 nm), while the ordinary grating spectrometers need 500 mm focal length to achieve this resolution. From this result, the advantages of the portable echelle spectrograph are fully demonstrated.
    No preview · Article · Dec 2012 · Guang pu xue yu guang pu fen xi = Guang pu
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, we employed the metal-enhanced fluorescence (MEF) method for the detection of polycyclic aromatic hydrocarbons (PAHs) in diesel oil emulsions in artificial seawater. Silver nanoparticles with an average diameter of 80 nm were immobilized onto silanized quartz as MEF substrates. Excited by illumination at 355 nm, a 4.6-fold increase in the fluorescence signals of PAHs was recorded when MEF substrates were used. The finite-difference time-domain (FDTD) method was used to provide mechanistic insights into the fluorescence enhancement. Monitoring water pollution has environmental significance and MEF spectroscopy is finding direct applications in this field.
    No preview · Article · Sep 2012 · Environmental Technology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Wavelength-dependent surface-enhanced Raman spectra of methylene blue adsorbed on rough submicrometer silver particles were measured. Results revealed a high enhancement factor (105 ∼ 107), especially in the long-wavelength region. Investigation on the far- and near-field optical properties of the particles showed a remarkably enhanced dipole plasmon resonance due to the presence of a rough particle surface. Through analyzing the plasmon resonance modes and the superposition of radiation fields, we found that the rough surface-induced field superposition results in the redistribution of optical fields around the particle, which becomes a key factor responsible for the high enhancement effect of metal particles.
    No preview · Article · Apr 2012 · Applied Physics Letters
  • Jie-ting Kou · Bayanheshig · Yu-guo Tang · Xiang-dong Qi · Hong-zhu Yu
    [Show abstract] [Hide abstract]
    ABSTRACT: The wavelength calibration research on the automatic grating monochromator for orthogonal Czerny-Turner structure was investigated. Combined with the structure parameters and characteristic of this monochromator, the sinusoid that accords with the grating equation was proposed as the function of the wavelength calibration. Based on the principle of the least square method, the formula of the fitting residual error of the wavelength calibration was given. Using the Nelder-Mead simplex method, the undetermined coefficient of the fitting residual error was solved, which founded the precise formula between the wavelength and the grating turning angle. The accuracy of the method was verified through the experiment. The calibrated wavelength precision of the monochromator is less than 0.1 nm, which satisfies the application requirement. Applied in the wavelength calibration of the automatic grating monochromator with orthogonal Czerny-Turner structure, this method is simple to apply and easy for implementation. Using this method, the wavelength calibration can be realized quickly and real-timely, but it is only needed to modify the control program of the stepping motor slightly, which shows a better practicability.
    No preview · Article · Apr 2012 · Guang pu xue yu guang pu fen xi = Guang pu
  • Jie-ting Kou · Bayanheshig · Yu-guo Tang · Xiang-dong Qi · Hong-zhu Yu
    [Show abstract] [Hide abstract]
    ABSTRACT: The plane grating double monochromator is the important part of the instrument for testing diffraction efficiency of plane grating, and in order to accomplish the research of the instrument, the optical system design and simulation of the plane grating double monochromator was investigated. The instrument mainly consists of light source, front monochromator, testing monochromator and detector, and combined with the practical requirement, the corresponding light source, detector and the structure of the optical path were selected. According to the design requirement, the design and simulation of the optical system of the front monochromator and testing monochromator were done respectively, and the spot diagram of the image surface and the results of real ray trace were given. The analysis showed that in the front monochromator the maximum width of the exit spot and the maximum height of the exit spot were 0.33 and 1.83 mm respectively. On the other hand, in the testing monochromator, the maximum width of the exit spot and the maximum height of the exit spot were 0.66 and 7.27 mm, respectively. Through selecting the size of the exit slit properly, the system can work without luminous flux lost, which guarantees the testing precision of the optical system of the instrument.
    No preview · Article · Mar 2012 · Guang pu xue yu guang pu fen xi = Guang pu
  • Yu-juan Liu · Yu-guo Tang · Bayanheshig · Ji-cheng Cui · Xiang-dong Qi
    [Show abstract] [Hide abstract]
    ABSTRACT: It is difficult for the traditional infrared imaging spectrometers to satisfy the requirement of high signal to noise ratio (SNR) and small size simultaneously. The new infrared remote sensing imaging spectrometers based on Dyson concentric optical configuration have the advantages of high aperture, high SNR, simpleness small volume and low weight. The Dyson imaging spectrometers can achieve high SNR, which is difficult for the traditional imaging spectrometers for infrared imaging spectrum. The present review introduces the beginning, the development and the present research of the Dyson imaging spectrometers, especially illustrates the principle of Dyson concentric spectrometer, difficulty during its manufacture and the application in the high-performance infrared remote sensing imaging spectrometers, providing a reference for the high-performance research of infrared remote sensing imaging spectrometers.
    No preview · Article · Feb 2012 · Guang pu xue yu guang pu fen xi = Guang pu
  • Hai-li Yu · Xiang-dong Qi · Bayanheshig · Yu-guo Tang
    [Show abstract] [Hide abstract]
    ABSTRACT: It is hard and costly to test resolution directly, because the focal length of testing equipment could be nearly ten meters. Solving resolution by diffraction wavefront aberration indirectly is an effective solution to this problem. A normalization model of solving resolution using fitting coefficients of Zernike polynomials was established based on the spectral imaging theory of Fourier optics. The relationship between resolution and wavefront aberration of diffraction gratings was illustrated by this model. Finally, a new method of testing resolution using fitting coefficients of Zernike polynomials was proposed. According to this method, the resolution of a grating is tested by ZYGO interferometer indirectly. Compared with direct method, results indicate that the error of indirect method is less than 4.22%, and this method could be an effective way to avoid the difficulty of direct method to solve resolution. Meanwhile, this method can be used in ZYGO interferometer to solve resolution by wavefront testing easily.
    No preview · Article · Jan 2012 · Guang pu xue yu guang pu fen xi = Guang pu
  • Xiang-dong Qi · Hai-li Yu
    [Show abstract] [Hide abstract]
    ABSTRACT: A new optical structure of measuring lead screw with dual-frequency laser interferometer is proposed, and a formula used quickly correcting Abbe error is deduced in this paper. In the process of testing lead screw, Abbe error in the measured data can be real time compensated, so that the measurement system which doesn't meet Abbe principle can achieve high measurement accuracy. In addition, this method can also eliminate measurement error induced by axial movement of the measured lead screw. The experimental result shows that of the maximum residual error is only 0.48μm within 300mm stroke after the maximum Abbe error 1.39μm is corrected. This method effectively improves the measurement accuracy of lead screw.
    No preview · Conference Paper · Jan 2010
  • Fang Wang · Xiang-Dong Qi · Hong-Zhu Yu · Hai-Li Yu
    [Show abstract] [Hide abstract]
    ABSTRACT: A new-style system that automatically measures the diffraction efficiency of plane reflection grating was designed. The continuous illuminant was adopted for illumination, the duplex grating spectrograph structure was applied, and the linear array NMOS was the receiving component. Wielding relevant principle of the grating spectrograph, theoretical analysis principle was carried out for the testing system. Integrating the aberration theory of geometrical optics, the image quality of this optics system was analyzed. Analysis indicated that the systematic device structure is compact, and electronics system is simplified. The system does not have the problem about wavelength sweep synchronization of the two grating spectrographs, and its wavelength repeatability is very good. So the precision is easy to guarantee. Compared with the former automated scheme, the production cost is reduced, moreover it is easy to operate, and the working efficiency is enhanced. The study showed that this automatic measurement instrument system features a spectral range of 190-1 100 nm and resolution is less than 3 nm, which entirely satisfies the design request. It is an economical and feasible plan.
    No preview · Article · Mar 2009 · Guang pu xue yu guang pu fen xi = Guang pu
  • Wen-Hao Li · Bayanheshig · Xiang-Dong Qi · Yu-Guo Tang
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel technology to manufacture holographic ion beam etched diffraction gratings based on surface thermokinematics is presented. The surface roughness of photoresist gratings is solved by this technology. According to this technology, a holographic ion beam etched blazed grating of 1200 l/mm for use in the ultraviolet region is manufactured. The experimental results show that the grating has good surface quality, low stray light and high diffraction efficiency. In addition, the performance of thes gratings satisfies the operating requirements of ultraviolet spectrograph.
    No preview · Article · May 2008 · Optoelectronics Letters