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Precise measurement of the micron-scale spot of ultrashort laser pulse based on film scanning

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Chinese Optics Letters 2008年第4期6卷 258-260页

作者：吴逢铁张建荣陈云彬郭东栋 College of Information Science and Engineering Huaqiao University Quanzhou 362021

A novel and precise micron-scale nanosecond laser spot measurement based on film-scanning method is presented. The method can be used to measure the spot size, beam profile, and intensity distribution of the pulse. The central spot radius of the pulsed Bessel beams with pulse width of 25 ns is measured to be 94.86 ± 5 μm in our experiment through the analysis of the digital image by film scanning, and the result is consistent with the theoretical value of 92.33 μm. Compared with charge-coupled device/complementary metal oxide semiconductor （CCD/CMOS） laser beam profilers, the film-scanning method shows higher measurement accuracy, single shot ultrashort pulse measurable, larger measurable size, and wider measurable wavelength range.

关键词： charge coupled devices Laser beams Laser pulses Light measurement Scanning

Fabrication of fiber-embedded multi-core photonic crystal fibers

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Chinese Optics Letters 2008年第10期6卷 715-717页

作者：孙伟民刘晓颀付枫华张建中 College of Science Harbin Engineering UniversityHarbin 150001

A novel fabrication method of multi-core photonic crystal fibers is proposed on the basis of a fiber-embedded technique. A taper tower is used to modify the structures of the fiber preform, and four steps of fiber fabrication and different structures of fiber samples are given. The mode structures and beating characteristics of a photonic crystal fiber sample with two successive cores are investigated in detail with the help of a supercontinuum light source, a charge-coupled device （CCD） camera, and an optical spectrum analyzer. The test results show a clear beating phenomenon between two orthotropic polarization modes with a 2.8-nm peak interval in wavelength.

关键词： charge coupled devices Crystal atomic structure Crystal whiskers Fabrication Laser pulses Light Light sources Lighting Optical fiber fabrication Photonic crystals Powders Spectrum analyzers coupled devices Embedded techniques Fabrication methods Mode structures Optical spectrum analyzers Photonic Crystal fibers Polarization modes Supercontinuum light sources Test results

Raman spectroscopy of Chinese human skin in vivo

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Chinese Optics Letters 2007年第2期5卷 105-107页

作者：李永增陈荣曾海山黄志伟冯尚源谢树森 Key Laboratory of Optoelectronic Science and Technology for Medicine (Fujian Normal University) Ministry of EducationFuzhou 350007 Cancer Imaging Department BC Cancer AgencyVancouverCanada

A novel and compact near-infrared （NIR） Raman system is developed using 785-nm diode laser, volumephase technology （VPT） holographic system, and NIR intensified charge-coupled device （CCD）. Signal-tonoise ratio （SNR） and resolution are improved compared with ordinary acquisition method by a specially designed optical fiber detector and the spectrograph image aberration correction with a parabolic-line fiber array. In 1-5 s, Raman spectra of different parts of Chinese human skin are acquired. Autofluorescence is subtracted from the raw spectrum by polynomial fitting and skin Raman spectrum is then smoothed for further analysis.

关键词： Aberrations charge coupled devices Detectors Optical fibers Polynomials Raman scattering Semiconductor lasers Signal to noise ratio Skin

Design of object surveillance system based on enhanced fish-eye lens

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Chinese Optics Letters 2009年第2期7卷 142-145页

作者：吴健辉杨坤涛项巧莲张南洋 College of Optoelectronic Science and Engineering Huazhong University of Science and Technology

A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-coupled device （CCD） surface, which increases both the utilization rate of the 4：3 rectangular CCD and the imaging resolution, and remains the view angle of 183° The algorithm of auto-adapted renewal background subtraction （ARBS） is also explored to extract the object from the monitoring image. The experimental result shows that the ARBS algorithm has high anti-jamming ability and high resolution, leading to excellent object detecting ability from the enhanced elliptical fish-eye image under varies environments. This system has potential applications in different security monitoring fields due to its wide monitoring space, simple structure, working stability, and reliability.

关键词： charge coupled devices Digital cameras Digital signal processors Fish Lenses Meats Optical instruments Security systems Signal processing

Interferometric measurement of injection nozzles using ultra-small fiber-optical probes

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Chinese Optics Letters 2011年第7期9卷 37-40页

作者： Tilo Pfeifer Robert Schmitt Niels Knig Guilherme Francisco Mallmann Fraunhofer Institute for Production Technology Steinbachstr. 17 52074 Aachen Germany Laboratory for Machine Tools and Production Engineering of RWTH Aachen University

The measurement of boreholes with diameters smaller than 500 μm is a demanding task that cannot be performed using state-of-the-art production metrology. In this letter, a miniaturized fiber probe with a diameter of 80μm is presented. A probe is used for low-coherence interferometry to conduct highly precise measurements of form deviations of small boreholes. Measurements conducted in nozzles are also presented. The results prove the potential of the fiber-optical sensor for quality inspection of high-precision parts, such as injection nozzles, for common-rail diesel engines.

关键词： charge coupled devices Fizeau interferometry Low coherence interferometry Metrology Michelson interferometers Optical fibers

Measurement of spatial object's exterior attitude based on linear CCD

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Chinese Optics Letters 2008年第7期6卷 505-509页

作者：艾莉莉袁峰丁振良 Department of Automatic Testing and Control Harbin Institute of TechnologyHarbin 150001

It is difficult to realize real-time measurement of exterior attitude by the traditional systems based on the area image sensor which have conflict between speed and accuracy. The subsystem for three-dimensional （3D） coordinate reconstruction of point target （S3DCRPT） which is composed of three one-dimensional （1D） cameras based on linear charge-coupled device （CCD） can determine the distant light spots＇ spatial position. The attitude angle of the measured object is determined by the spatial solution while the coordinate reconstruction is separately carried on by the S3DCRPT with some point cooperation targets （PCTs） on the measured object. A new optical system is designed to solve the interference problem with one-to-one relationship between the PCTs and the S3DCRPT optical subsystems, which improves the measurement accuracy and saves space. The mathematical model of the attitude measurement is established, and partial and global calibrations are realized for the multi-camera attitude measurement system. The test results show the feasibility of the exterior attitude measurement based on linear CCD.

关键词： Cameras charge coupled devices Computer networks Digital cameras Ketones Mathematical models Optical systems Real time systems Restoration Time measurement

Photoeletricity Capability of Imager Detector with Coated Blends of Polymer and Perylene or Coronene

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Chinese Physics Letters 2003年第1期20卷 161-163页

作者：杨冰李瑛等 FacultyofChemistry SichuanUniversityChengdu610064

Perylene and coronene have been synthesized with good yield via the Dields-Alder reaction. They have good photoluminescence properties and could transfer ultraviolet light to visible-light. To find an easy way of making a better ultraviolet charge coupled device, we blended perylene or coronene with polymers. Then, these blends were analysed by the photoluminescence spectrum. The results indicate that the blends have larger fluorescence intensity than pure perylene or coronene. Through spreading these blends on image detectors, organic image detectors with good ultraviolet photoelectricity capability were prepared.

关键词： charge coupled devices

Spectral calibration in spectral domain optical coherence tomography

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Chinese Optics Letters 2008年第12期6卷 902-904页

作者：王凯丁志华 State Key Lab of Modern Optical Instrumentation Zhejiang University

A novel spectral calibration method is developed for spectral domain optical coherence tomography system. The method is based on two measurements of interference spectra from two reference mirror positions. It removes the influence of dispersion mismatch, and hence accurately determines the spectral distribution on the line-scan charge-coupled device （CCD） for sequent precise interpolation. High quality imaging can be realized with this method. Elimination of the degradation effect caused by dispersion mismatch is verified experimentally, and improved two-dimensional （2D） imaging of fresh orange pulp based on the proposed spectral calibration method is demonstrated.

关键词： Calibration charge coupled devices Diagnostic radiography Medical imaging Optical tomography Photodegradation Strain measurement Tomography

An Automatic System of Vehicle Number-Plate Recognition Based on Neural Networks

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Journal of Systems Engineering and Electronics 2001年第2期12卷 63-72页

作者： Wei Wu Dept. of Road and Traffic Engineering, Changsha Communications University, 410076, P. R. China Huang Xinhan, Wang Min & Song Yexin Dept. of Control Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China Dept. of Road and Traffic Engineering Changsha Communications University 410076 P. R. China Dept. of Control Science and Engineering Huazhong University of Science and Technology Wuhan 430074 P. R. China

This paper presents an automatic system of vehicle number-plate recognition based on neural networks. In this system, location of number-plate and recognition of characters in number-plate can be automatically completed. Pixel colors of Number-plate area are classified using neural network, then color features are extracted by analyzing scanning lines of the cross-section of number-plate. It takes full use of number-plate color features to locate number-plate. Characters in number-plate can be effectively recognized using the neural networks. Experimental results show that the correct rate of number-plate location is close to 100%, and the time of number-plate location is less than 1 second. Moreover, recognition rate of characters is improved due to the known number-plate type. It is also observed that this system is not sensitive to variations of weather, illumination and vehicle speed. In addition, and also the size of number-plate need not to be known in prior. This system is of crucial significance to apply and spread the automatic system of vehicle number-plate recognition.

关键词： Cameras charge coupled devices Feature extraction Neural networks Vehicles