AC stark interference effect in optical Ramsey atomic interferometer
Author(s):
Jingbiao Chen
Show Abstract
In an optical Ramsey atomic interferometer using Ramsey separated oscillating fields method, AC Stark effect shows that an interference feature is superimposed on the AC Stark level shift dispersion line-shape. This phenomenon has never been observed before. In this report, an analytic expression of the AC Stark shift in optical Ramsey atomic interferometer has been derived, and the numerical result of this interesting feature has been analyzed. Finally, the condition to measure the Interference of AC Stark Effect has been discussed.
Approach for the measurement of phase retardation of wave plates based on laser frequency splitting technology
Author(s):
Yi Zhang;
Shulian Zhang
Show Abstract
A novel method for measurement of optical retardation angles of wave plates is presented based on laser birefringent longitudinal mode splitting technology. With this method, a measurement system was developed that the related experiments were conducted. The method has relatively concise setup and reaches high resolution and accuracy. With a intensity-contrasting beat locking unit, the error level is less than 8 angular minutes for the measurement of 0.6382micrometers crystal quarter wave plate.
Experimental research on laser tracking system with galvanometer scanner for measuring spatial coordinates of moving target
Author(s):
Jia Wang;
Zhaohui Hu;
Yongdong Liu;
Jinwen Liang
Show Abstract
The spatial position of industrial object, such as robot end- effector, is an important geometric parameter whose accuracy determines whether robot can perform accurately. Therefore, we have established a laser tracking and coordinate measuring system with galvanometer scanner for high accuracy, large range, non- contact, and spatial dynamic measurement. In this paper, the laser tracking system and its setup are illuminated at first. Then, the formulae for calculating coordinates are deduced, and the calibration method of the initial distance from tracking mirror to target is presented. After that, two preliminary experiments in different distances are described. One is on CMM; the other is with grating ruler as reference. In the former, the maximum measurement error of coordinates is 70micrometers and the maximum error of length is 35micrometers in the 85x100x100mm3 measurement volume, and in the 1m initial distance. In the later, the maximum error of length is 140micrometers in the range of 480mm, and in the 5m initial distance. At the end of the paper, the error sources are analyzed and simulated.
Automatic inspection system for wheel-aligning parameters
Author(s):
Dahai Ren;
Xun Jiang;
Qiuyan Wu;
Zheng You
Show Abstract
The measurement of the wheel-aligning parameters is very important in the production of vehicles. In this paper, we present a non-contact measuring technique for the inspection of wheel-aligning quality in which the laser triangulation is employed based on structural light sensors. First, the main purpose of the inspection is introduced with corresponding parameters illustrated. Meanwhile, the main principles of the system and the structural light sensors are analyzed in detail. In the paper, the image processing techniques are studied, which include the noise eliminating algorithms and the symbol extraction methods. The image quality is effectively improved and the object points are successfully extracted by these methods. Moreover, the corresponding models are presented for the aligning parameters required. Using the techniques presented in the paper, an inspection system for the wheel-aligning parameters is fulfilled by which the automatic inspection is achieved.
New advance in laser interferometry
Author(s):
Chunyong Yin;
Zhixia Chao;
Sai Gao;
Hong Jiang;
Jin Sun
Show Abstract
Modern technology development requires interferometry of uttermost quality, which is characterized as high measurement speed, large measurement range, low drift and super-high resolution, good accuracy and efficiency. Firstly this paper introduces a frequency stabilized laser with 5MHz beat frequency which is based on the bi-reflection principle, and a high measurement speed dual-frequency laser interferometer whose allowable displacement velocity is over 1m/s using this kind of laser. Secondly it introduces a transverse Zeeman frequency stabilized laser with 300KHz beat frequency and its applications in nanometer measurement, collimation, coaxiality measurement, roll angle measurement and biomembrane measurement. Thirdly a tunable 633nm external-cavity diode laser (ECL) interferometer is presented.
Fringe projection method for measuring 3D profile and position of a moving object
Author(s):
Fan Yuan;
Deqiang Song;
LiJiang Zeng
Show Abstract
It is difficult to measure three dimension profile and positions of a moving object by using only one group of grating projection fringes because the absolute position of the object couldn't be determined. We introduce two reference-tracking fringes into the conventional fringe pattern projection system, from which we determine the moving direction and absolute coordinate of the moving object. The 3D profile of the object is determined from the distorted fringes, and the absolute coordinate of that is determined from the angle of the reference-tracking fringes. This method enables us to track a moving object, and measure it with a large measurement range.
3D en face imaging by OCT
Author(s):
Shan Sun;
Jiansong Gao;
Lei Wang;
Ping Xue;
Die Yan Chen
Show Abstract
Optical Coherence Tomography (OCT) is a kind of new tomography technology, which has much important application in biological, medical and material science. In this paper, we make continuations of this technology to found en face imaging of arbitrary object. This enables us to get digital information about the geometrical configuration of a sample with resolution of micrometers in a non-touching mode.
Application of wavelet de-noise in digital speckle correlation method
Author(s):
Xuefeng Yao;
Guan-chang Jin;
Wu Zhen
Show Abstract
De-noise effects of wavelet analysis technique on Digital speckle correlation method (DSCM) are described in this paper. The principle of wavelet de-noise in digital speckle correlation is shown and the related algorithm structure is given. A series of DSCM experimental results, such as zero displacement, rigid body movement and 3-point-bending deformation, are handled. These results reveal that Wavelet analysis technique has better de- noise effect in the DSCM and the measure precision can reach to 0.01-0.005 pixel. This advanced DSCM provides a precision deformation measurement tool in optical metrology.
Aberration measurement of focal mirror by the phase shift in high-power CO2 laser processing
Author(s):
Zhiyong Wang;
Hong Chen;
Tiechuan Zuo
Show Abstract
In this paper, a new method to measure the aberration of focal mirror under high-power CO2 laser beam irradiation by phase shift is proposed. The aberration caused by distortion of focal mirror changes the phase shift of laser beam. Therefore, the transverse intensity distribution (TID) on focus of the focal mirror under the high-power CO2 laser beam irradiation is different from the ideal distribution. Furthermore, the changes of phase shift can be solved by comparing this difference. As well as the aberration can be obtained.
Key factors in accurate beam characterization application
Author(s):
Wei Sun;
Chunqing Gao;
Guang Hui Wei
Show Abstract
The accuracy of CCD based laser beam characterization has been widely discussed for years in the industry. As we know the obtained accuracy of laser beam characterization depends strongly on many factors of the CCD measurement system and on the properties of the laser beam's power density distribution to be measured. In this paper we discussed the influence of these factors through simulated calculation and investigation. A mathematically generated Gaussian and Super Gaussian beam was computer generated, background and random noise with a Gaussian distribution were added to the mathematically generated beam. Measurements were then made based on second moment method with is a ISO definition. We change the background, noise level and the size of integration area during the simulated calculation so as to determine the influence on the accuracy of beam width measurement of these different factors. The research result shows that image background subtraction and noise control play a very important role in the accurate measurement system and application. According to the investigation we designed a measurement system and application which has high dynamic range, an appropriate processing and calculation algorithm which can control the background and random noise effectively so that get high beam measurement accuracy.
Physical experimental simulation of indirect surface display caused by buried geological anomaly
Author(s):
Jianping Chen;
Qing Li;
Jin Xu
Show Abstract
Through the physical experiment simulation of the lineaments on the surface, the paper reveals the mechanism and genesis of the indirect display caused by buried geological anomaly. A view that RS image can show the character of buried geological anomaly is put forward in the paper. In order to prove the view, a physical model which includes basement and cover is established. Firstly, it makes an analysis of model and expounds the condition for simulation. Secondly, it describes the process of simulation and its results. The model is mainly designed to measure the deformation of its cover, which includes two stages. During the first stage, three-dimension stress field of cover itself mainly controls the deformation. During the second stage, the deformation of cover is mainly controlled by the activity style of the buried structure. The development character of this stage is quite incompatible. Finally, it concludes that the track of deformation crack composed by surface lineaments and those information quite incompatible with background character are very likely the indirect display of buried geological anomaly. So the selection of this information is very important for revealing the creation and genesis of buried geological anomaly.
Selection of pattern in slit diffraction measurement and its influence on measurement accuracy
Author(s):
Fuping Liang
Show Abstract
The serial parameters such as slit width, wire diameters and plate thickness can be measured by application of diffraction, and it can be derived to measure the variables of interval, displacement, strain, section and the others. The field distribution of slit diffraction are investigated, and the extreme values of slit diffraction are given step-by-step approach with computer. The influence of selecting the pattern and the level of the comparator for video frequency output of CCD/CCPD upon measurement accuracy are analyzed.
Solar panel substrate planeness measuring system by an optical triangulation method
Author(s):
Jian-cheng Fang;
Jian-hui Zhao;
Shiping Zhu
Show Abstract
The planeness measurement of solar panel substrate is a key problem in the manufacture procedure of satellites. The current measuring methods have the problems such as low precision and low efficiency. Based on the actual engineering project of the solar panel substrate planeness measuring system, a solar panel substrate planeness non-contact measuring system is presented, which employs an optical triangulation method and bases on virtual precise datum plane. By means of a declinate optical triangulation measuring instrument structure which is firstly proposed, the measured area and resolution of this measuring system are greatly increased, and the high accuracy non-contact measurement of the planeness of a large area plane is realized. On the basis of a new modeling method of virtual precise datum plane and measurement error compensation technique, the measuring system can accurately measure the solar panel substrate planeness on a non-precision plate. The actual measurement results show that the measurement accuracy 0.02mm (RMS) can be obtained when a solar panel substrate (2581mmx1755mm) planeness is measured by using of this measuring system.
New application of holography and interferometry in temperature sensing
Author(s):
Jing Zhou;
Henry F. Taylor
Show Abstract
A new application of holography and interferometry in temperature sensing is proposed in this paper. Using holographic technique and electron lithography, a grating can be made in a fiber's end. This structure can be used to test the temperature change. By examining the interfering pattern of diffract lights of the grating, the temperature change can be calculated. If using the work wavelength of 1.55micrometers , the temperature testing range can theoretically be 1179 degree(s)C.
Principle demonstration of 3D volumetric display achieved by PrYb co-doped material
Author(s):
Xiaobo Chen;
Yu-Xin Nie
Show Abstract
Up-conversion three-dimensional volumetric display is a new application and hot-point of frequency up-conversion research. It is elected as one of the nicest international physics achievement in 1996. This paper reports the principle demonstrate works in up-conversion three-dimensional volumetric display. The used mechanism is di-frequency up-conversion sensitization proposed by authors firstly. The used material is Pr3+Yb3+:ZBLAN glass.
Basic optical property of Tm-doped oxyfluoride vitroceramics and glass
Author(s):
Xiaobo Chen;
Cenjun He;
N. Sawanobori;
Meng Chao;
Luan Chen
Show Abstract
The transparent rare-earth ion doped oxyfluoride vitroceramics is a new kind of nanometer material, whose structure was thought comprised of fluoride microcrystals in an oxide glass matrix. It may have not only high up-conversion efficiency but also good material property. This paper studies the optical absorption and emission properties of the Tm3+-doped oxyfluoride vitroceramics (FOV) and glass (FOG). It is possible to be a good up-conversion 3D volumetric display material.
Raman and x-ray diffraction study on the material property of oxyfluoride vitroceramics
Author(s):
Xiaobo Chen;
N. Sawanobori;
Yulong Liu
Show Abstract
Upconversion study is imperative now to find good material that has high laser damage threshold, good physics and chemical property, easy in processing in order to develop various up- conversion applications. This paper studies the material property of oxyfluoride vitroceramics by Raman and x-ray diffraction spectroscopy. It reveals the physical reason why the Er3+ ion's upconversion luminescence in oxyfluoride vitroceramics is 101 times greater than that in oxyfluoride glass.
Oxyfluoride vitroceramics material and up-conversion luminescence enhancement of Er3+ion
Author(s):
Xiaobo Chen;
Yu-Xin Nie
Show Abstract
Er3+ ion is such a kind of rare earth ions that has most splendid upconversion luminous phenomenon. It is very significant also to find some new mechanism, method and material to enhance the upconversion efficiency. This paper investigates the material and luminescence property of ErYb codoped oxyfluoride vitroceramics. In out experiment device, Optical Measurement could be proceeded very precisely, sensitively and nondestructively. Our research finds that oxyfluoride vitroceramics has good luminous property. The rare earth ions, which are within a same micro-crystallite, are easy to consist of couple-group. The intense cluster effects have emerged. It results in that the Er3+ ion's upconversion luminescence in oxyfluoride vitroceramics is ten times greater than that in oxyfluoride glass and ZBLAN fluoride glass.
Modulation inspection: best lifetime measurement method of delicacy material
Author(s):
Xiaobo Chen;
Xiaowen Li;
Luan Chen
Show Abstract
Modulation lifetime inspections a new kind measurement mechanism in Frequency Domain. A CW tunable Xe lamp is used as a pumping source, which is modulated first and excites sample sequentially. The lifetime could be obtained by analyzing its demodulation (m) and phase shift ((phi) ). Because the excitation light power density is only about 1W/s, the lifetime of delicacy material could be inspected beautifully, accurately and nondestructively. Thus it is undoubted that Modulation Inspection is the best method for lifetime measurement of delicacy material.
Color-coded grating 3D profile measurement and its application
Author(s):
Weiyi Liu;
Zhaoqi Wang;
Guoguang Mu;
ZhiLiang Fang
Show Abstract
A fast and efficient technique for profilometric measurement using color-coded grating is proposed. Four colors are used to code the grating and each color represents only one logical state. There are 48 stripes in one period of the color grating, which is large enough for normal measurement. As compared with the previous techniques, it has the advantages of simple hardware without moving mechanical part, single exposure for obtaining 3D information, little influence of the noise and the nonlinearity of the CCD camera on the measurement accuracy, and higher anti- color-blurring capability. The suggested technique is suitable for on-line inspection and dynamic measurement of moving objects.
Structural resonances in the Raman spectrum of glass microsphere
Author(s):
Ji-You Wang;
Xiao xuan Xu;
Cun zhou Zhang
Show Abstract
Structural resonances have been found in the Raman spectrum of an optically levitated TiBa glass microsphere. The observed resonances could be assigned by using the well-known Lorenz-Mie Formalism. It was found that the diameter of the TiBa glass microsphere is 24.490micrometers , and the refractive index of TiBa glass is 1.895 at about 645nm.
Polarization properties of volume hologram
Author(s):
Shuo Lu;
Wenyao Liu;
Wei Zheng;
Yongjie Hao;
Dahe Liu
Show Abstract
The diffraction efficiency of volume hologram is calculated by using the character matrix of multilayer medium films. The polarization characteristic of volume holographic grating is discussed in detail, while the diffraction properties are analyzed respectively for p-polarized light and s-polarized light by computer simulation. We have found that the diffraction efficiency of reflection hologram can be highly dependent on the polarization of incident light.
3D computer vision system based on spatial phase mapping
Author(s):
Xiang Peng;
Weiqiang Shi;
Zonghua Zhang;
Xiaotang Hu
Show Abstract
This paper presents an active 3D vision system that is based on spatial phase mapping technique. The operating principle and unique features of the system is briefly described. The emphasis of this paper is on the description of software design and implementation of the system. The strategy and methodology for the software architecture design of the vision system is discussed in detail. The experimental results obtained from this kind of vision system are also given to show the effectiveness of the system.
New method for multiview range image fusion
Author(s):
Zonghua Zhang;
Xiang Peng;
Weiqiang Shi;
Xiaotang Hu
Show Abstract
Based on the concept of Main-Stitched-Line (MSL) and Sub- Stitched-Line (SSL), this article presents a new integration method for multiple range images. The MSL and SSL can be found from range images in the first view R1, and the second view, R2, respectively. Then following by a triangulation process we can construct a non-redundant geometric representation of combined range images. The experimental results show that the integration technique proposed in this paper can quickly and efficiently build up surface models of an object from multiple range images.
Wavelet analysis and its application in PDA signal processing
Author(s):
Zhoumo Zeng;
Hongbo Lu;
Yinsheng Pan
Show Abstract
In this paper a problem associated with the detection and identification of Doppler signal is discussed, and a new PDA (phase Doppler Anemometry) signal processing method based on the wavelet analysis is proposed. This method improves the ability of PDA signal processing both in time and frequency domain and gives another option of signal identification and processing for PDA measurement.
Surface 3D topography measurement of roller
Author(s):
Jianfeng Jiang;
Yonghui He;
Wansheng Zhao;
Yaohuan Xu;
Guozheng Yan
Show Abstract
In order to adapt to the trend of surface quality assessment, the 3D topography measurement becomes more and more important. In metallurgy industry, the topography of roller affects that of cold-rolled steel sheet mainly, which makes it necessary to measure the topography of roller. On the base of traditional light section method and light scanning technique, the triangular light beam scanning method is designed and adopts linear structured light to scanning test surface and acquire height data through demodulating the surface 3D information carried from observation field. Applied with the TLBS surface topography measuring system, some 3D topography examples are given to verify the correctness and feasibility of it.
Highly sensitive method for concentration and absorption measurements by guided-wave resonance
Author(s):
Guang Chen;
Yi Jiang;
Zhuangqi Cao;
Qishun Shen;
Xiaoming Dou;
Hideo Tashiro
Show Abstract
In this paper the mechanism responsible for the sensitivity enhancement is theoretically analyzed. The thickness of the coupling film is optimized to obtain better sensor performance. It is verified that the result of present method offers more sensitive detection than that of the conventional SPR technique does. The biosensor applications for this technique are also discussed.
Real-time measurement for the electro-optic coefficient of a poled-polymer film in ATR configuration
Author(s):
Bo Yuan;
Zhuangqi Cao;
Qishun Shen;
Yingli Chen;
X. Dou;
Hideo Tashiro
Show Abstract
A new method which bases on the attenuated total reflection (ATR) technique is developed to determine the electro-optic coefficient of a poled-polymer film. The proposed ATR arrangement consists of a coupling prism, and four film layers deposited directly onto the base of the prism in sequence. The four film layers are metal film (which serves as a top electrode), poled polymer film, buffer and base electrode, respectively. A convergent light beam covering a suitable angular range is incident onto the prism base to excite a guided wave mode and the reflected light beam is imaged by a CCD array. Then resonance angle of the guided wave mode can be determined from the position of the reflectance minimum. It is demonstrated that the applying electrical field will cause a minute change in the refractive index of a poled- polymer film, due to the Pockles effect, which will result in a shift of the resonance angle. In order to make the measurement more successful, computer image processing method and optical image spatial filter technology are used in our measurement.
New method for the recovery of the refractive-index profile of an optical waveguide from the measured coupling angles
Author(s):
Qing Liu;
Zhuangqi Cao;
Qishun Shen;
Xiaoming Dou;
Yingli Chen;
Yukihiro Ozaki
Show Abstract
In this paper, we present a new method used for the recovery of the refractive-index profile of an optical waveguide from the measured coupling angles. Two improvements have been made in our method. First, we determine the surface refractive index of the inhomogeneous waveguide by experiment technique, instead of usual numerical methods. Second, we present a new fitting criterion which is based on the accurate ATMM (Analytic Transfer Matrix Method), but not approximate WKB theory. Experimental results demonstrate our method could give better results compared with the previous techniques.
Correlative stitching technique for measuring flatness
Author(s):
Yingjie Yu
Show Abstract
In flatness measuring by correlative stitching technique, a bigger scale's measurement can be realized by the system witha smaller measurement caliber. At the same time, high measurement precision, high spatial resolution and low price can be maintained. In this technique, mode building and solving are especially important. Aiming at some problems in common mode building and solving, the paper presents a new solving method. The iterative least-squares technique is applied in the method and it considers not only the information in height, but also the influence of the parameters in other directions which are usually predigested in common modes. By this solving method, the demand for rail of systems is decreased. Some simitations are done to testify the presented method.
Measurement of group time delay of a chirped fiber grating
Author(s):
Lin Li;
Haiwen Cai;
Ronghui Qu;
Zujie Fang
Show Abstract
A method of measuring the group time-delay of chirped fiber grating g(CFG) is presented in this paper. This approach is based on mode-mocking technique. An F-P cavity LD and a linearly CFG under test compound together to be an external cavity laser. Group time-delay can be investigated by measuring adjusted RF frequency and corresponding lasing wavelength.
Testing optical aspheric surfaces by aspheric characteristic interferogram
Author(s):
Weimin Zheng;
Tianning Cao
Show Abstract
The interference pattern of the optical path difference between an aspherical optical surface and the corresponding best fit spherical surface is the Aspherics Characteristic Interferogram (ACI), which can be used as a template to test aspheric optical surfaces without test plates or null compensation systems. This direct interferometry can be used in the optical shop testing and in the digital phase-shifting spherical Fizeau interferometer to achieve high precise aspheric surface testing automatically. We succeeded in testing several aspheric surfaces by this method. ACI is also the base of phasing segmented mirrors, and six small- segmented mirrors were successfully combinated to a large mirror. If used in the infrared red interferometer, strongly aspheric surfaces with asphericity more than 40micrometers can also be tested. Experiments show that the ACI is a fast, effective aspherical surface measurement technique.
Laser microprobe emission spectrum in argon atmosphere at reduced pressure
Author(s):
Qinglin Guo;
Yanhong Wei;
Jinzhong Chen;
Sufang Huai;
Baolai Liang
Show Abstract
In this research, we experimentally studied the spectral quality of the CUl324.7nm and Cul327.4nm lines of the copper alloy standard samples in argon atmosphere at reduced pressure by a laser microprobe emission spectral analysis (LMESA) system. Compared with the results obtained in air atmosphere with the pressure of 760Torr, the spectral quality of the lines obtained obvious improvement. As the distance between the two graphite electrodes is 4mm and the pressure is 250Torr, the intensity of the spectral lines is about 2-3 times of that in the air atmosphere and the Full-Width-at-Half-Maximum (FWHM) is nearly one third of that in the air atmosphere.
Real-time algorithm in the virtual environment
Author(s):
Feng Gui;
QiWei Lin
Show Abstract
In order to render the virtual terrain environment in real-time, a view-dependent continuous LOD algorithm is presented in this paper. We analyze the regularity of the regular grid Digital Elevation Model and employ three view-dependent criteria to reduce the complexity of the terrain in real-time: (1) screen space error; (2) view-frustum intersection; (3) node orientation. The experiment results indicate that this algorithm can attain a much higher frame rate in rendering the virtual terrain environment, as well as in maintaining the visual quality.
Optical fiber sensor system for oil contamination measurement based on 3D fluorescence spectrum parameterization
Author(s):
Liping Shang;
Jinshan Shi
Show Abstract
In recent years oil contamination in water is more serious and destroys the mode of life and relation to water body environments. Excitation fluorescence method is one of the main approaches to monitor oil contamination on line. But average intensity of oil fluorescence only indicates its density, not indicates the type of contamination oil. Two-dimensional fluorescence spectrum is more difficult to determine the kind of oil, because the different oil has fluorescence spectrum overlapping to a great extent. In this paper, the 3D fluorescence spectrum parameterization is introduced. It can extract several characteristic parameters to measure the kid of oil to be measured. A prototype of optical fiber 3D fluorescence spectrum meter we developed carries out the identification of different oil types, such as crude oil, diesel oil and kerosene. The experiment arrangement conceived to measure pulse xenon lamp induced of oil component in water. The experiment results state clearly that the 3D fluorescence spectrum parameterization and software are successful to measure oil density and identify the type of oil in situ.
PIV measurements and data accuracy analysis of flow in complex terrain
Author(s):
Rentai Yao;
Hongwei Hao;
Qingdang Qiao
Show Abstract
In this paper velocity fields and flow visualization in complex terrain in an environmental wind tunnel have been measured using PIV. In addition, it would be useful to appraise the PIV data by comparing the PIV results with those obtained from the well- established point measurement methods, such as constant temperature anemometry (CTA) and Dantec FlowMaster, in order to verify the accuracy of PIV measurements. The results indicate that PIV is a powerful tool for velocity measurements in the environmental wind tunnel.
Diffraction analysis and evaluation of a focus-error detection scheme for an optical profilometer
Author(s):
Chunlan Yang;
Zhaobang Pu;
Huijie Zhao
Show Abstract
A high resolution non-contact optical sensor for surface roughness has been developed. The principle of the sensor is based on the dynamic focusing in combination with astigmatic method, a popular focus-error detection approach. The measuring principle of the method and the optical system arrangement are described in detail firstly. Then, a mathematical model of the system based on Fresnel diffraction theory is derived. According to the model, a plot of the focus error signal (FES) versus the misfocusing is easily got. The effect of various system parameters on the FES is discussed, and this is very useful for system optimization. Besides, results of numerical calculation, namely optical field distributions on the quadrant photodetector surface at different misfocusing, are presented.
Nondestructive survey of a buried surface and interface structure by x-ray scattering
Author(s):
Wenjun Ma;
J. E. Macdonald;
Gang Jia
Show Abstract
X-ray scattering as a nondestructive probe was used in studying surface and interface structure. Two monolayers InAs was found to be existence between InGaAs and InP by simulating scattering data. The interfacial effects on peak-separation of substrate to epilayer and on layer thickness were simulated.
Submicron electro-optic measurement technique using an external hemispherical probe
Author(s):
Zhanguo Chen;
Gang Jia;
Zhifa Wu;
Yunlong Liu;
Chao Zhao;
Maobin Yi
Show Abstract
In this paper an external electro-optic measuring system based on a hemispherical GaAs probe is presented. By using the system, the electrical signals propagating on a microstrip transmission line are successfully measured. The spatial resolution of the system, which is limited by the focused probing spot size, is about 0.5 micrometers , when the wavelength of the probing beam is 1.3 micrometers .
New application of integrating sphere
Author(s):
Jinjiang Wang;
Ye Wang;
Zhiwen Yang
Show Abstract
In the paper, a model of integrating sphere, which acts as a low- light-level source, is constructed on the basis of researching of the theory of integrating sphere and the method of Monte Carlo. The uniform distribution of photons is simulated by a large number of random numbers and the distribution of photons in the integrating sphere is molded. The method is practical to guide the design of integrating sphere. At last, the measurements to improve precise are discussed simultaneous.
Measurement of a large 3D curved surface
Author(s):
Jinjiang Wang;
Jun Chang;
Yongkai Zhu;
Zhiwen Yang
Show Abstract
There are many modern methods to measure large 3D curved surface, such as the method of flying time, the method of laser triangulation, the method of photogrammetry, the method of measurement with intersection of electronic-theodolites, the method of raster projection, and the method of Fourier transform profile. In this paper, these methods will be discussed respectively.
Second harmonic generation in B-BaB2O4 thin films
Author(s):
Xiyan Zhang;
Zhifeng Cao;
Li Li;
Zhaohui Bai;
Jing he Liu;
Wenshi Wang
Show Abstract
The β-BaB2O4 thin films were prepared by the sol-gel method. The nucleation agent was added in favor of crystallization of the thin films. The second harmonic generation (SHG) was measured by using a Q-switched Nd:YAG laser.
Photoluminescence measurement of SrAl2O4:Eu2+,Dy3+ incorporated in glass frits
Author(s):
Xiyan Zhang;
Zhifeng Cao;
Zhaohui Bai;
Li Li;
Zhiqiang Zhao;
Jinxiu Du
Show Abstract
In this paper glass frits were prepared by the melting and quenching method. The SrAl2O4:Eu2+,Dy3+ was incorporated in the glass frits by firing them on a glass substrate. The photo luminescence was measured in terms of excitation and emission spectra. Effects of firing temperature on the phosphorescence persistence were measured.
Noncontact measuring technique of spline bouncing error
Author(s):
Zhiyong An;
Jinliang Feng;
Wenbo Han
Show Abstract
In accordance with the structural characteristic and the form- and-position error demand of spline axis, a kind of measuring means is put forward in this paper to solve bouncing error of centering diameter on spline axis. Considering the noncontact laser measuring head, which uses the principle of laser optical triangle, the basic working principle of laser measuring head and the structure of measuring system are described in detail, and they are verified in the experiment.
Closed-loop dynamic inspections by two-dimensional laser scan
Author(s):
Xiaoman Wang;
Lu Song;
Jinliang Feng
Show Abstract
In this paper we have described the fundamental principle and the concrete means of two-dimensional closed loop dynamic inspection system with laser scan. We have made an inquiry into the basic factors of affecting system stability and accuracy, and have given the concrete experimental data.
Stereo matching algorithm using wavelet transform
Author(s):
Cun Xie;
Jia-sheng Hu
Show Abstract
Stereo matching is an important and necessary technique for stereo vision. It is usually not good practice to try to find corresponding points for all pixels, and feature points are selected so that unambiguous matches might be obtained. Meantime, in order to reduce the computational cost of finding correspondence, multistage matching is often applied. Wavelet transform has good multi-resolution representation. Using zero- crossing points of wavelet transform coefficients as the features, the corresponding features in a pari of images are found by decomposing images into several levels (multi-scale analysis). So disparity estimation and error exclusion can be finished simultaneously. The efficiency of this algorithm is increased. Finally, the given algorithm is tested on stereo image pairs.
Image-based recognition of the chip shape
Author(s):
Xianli Liu;
Guoliang Zhao;
Lin Lin;
An Meng
Show Abstract
According to the profile characteristics of the extracted chip form and the number of nodes between profile and * line which have the same gravity, chip species are discerned. The chip types near the critical joint are judged exactly through the standard tolerance of all direction nodes. It was tested to have a high accordant rate.
Microarray imaging system for measuring the properties of a moving object
Author(s):
Weijian Tian;
Min Huang;
Rongli Chen;
Xiaojun Li;
Wei Zhang
Show Abstract
A micro-array imaging system with multi-channel, parallel processing is proposed in this paper. Compared with the single- aperture imaging system, the array imaging system has some advantages- wider view field to prevent losing target, and higher sensitivity for moving as the compound eyes of insects. Utilizing the moving sensitivity, one is able to measure the properties of moving object, like speed, acceleration, direction and so on. A microlens array plays an important role in the micro-array imaging system. Based on the system construction and the visual principle, several experimental and evaluating results are introduced. Meanwhile, new approaches of image capturing and data processing to solve the contradiction between view field and resolution are discussed initially.
Laser measurement for slight deformation of a large-scale structure
Author(s):
Yaxing Yi;
Zhongke Li;
Xinshe Li;
Fanglin Deng
Show Abstract
This article is to introduce the outline of our newly developed method of laser measurement for slight deformation of large-scale building or structure, which we call the automatic inspection for the six-degree-of-freedom movement-deformation of distributed interconnected measure-points. The basic principle is described as below: A certain number of measure-points are settle on the building that is waiting for inspection. In all measure-points, we select one as a datum point. For every two connected measure- points, we measure their relative displacement of six-degree-of- freedom, then, we calculate out the relative displacement of six- degree-of-freedom for every measure-point to datum point. By this way, we can know the deformation of the building. The measuring method of relative displacement for every two connected measure-points is presented as below: An indium steel pipe, which acts as a length rod and a displacement sensor, are used to inspect the distance of the two measure-point. A collimating laser beam and a two-dimensional PSD are used to inspect the other two dimensional linear displacement. A collimating laser beam, a reflector and a one-dimensional PSD are used to inspect the relative rotation in horizontal plane. A high precision photoelectric tiltmeter which is especially developed for this purpose is used to inspect the other two dimensional angular displacement. All those measurement are controlled by a central computer, and full automatic.
Dynamic IR scene projection using the single-crystal silicon liquid crystal light valve
Author(s):
JiaoBo Gao;
Ke-fei Ye;
Jun Wang;
HuiLing Chen;
Peng Jiang;
Cuiying Zhang
Show Abstract
Detailed description of the structure, operation and performance of single crystal silicon infrared liquid crystal light valve (IR-LCLV) is given. Experiment results obtained from an IR-LCLV utilizing Epson projector as the visible image input source and an extended IR source (blackbody) as the projection beam is presented. Spatial resolution is 20 lines/mm and dynamic temperature range is 80 degree(s)C above ambient.
Digital Fourier analysis method for measuring the optical MTF of an IR imaging scanner
Author(s):
Mingyin Jiao;
Zhuoxiang Feng
Show Abstract
The digital Fourier analysis method for optical MTF of IR imaging scanner is described and discussed in this paper. The method obtain the LSF by making use of the scanning function of the scanner itself besides the target slot and reflective collimator as well as the SPRITE detector and its read-out circuit which are practically used in IR image assembling process, and the MTF are calculated by DFT. The method makes a feature of simple equipment, easy operation and quick calculation.
Three-dimensional optical tomography of incomplete data
Author(s):
Zhengdong Wang;
Zhenhua Li;
Anzhi He
Show Abstract
In this paper, three-dimensional optical computerized tomography in the case of severely incomplete projection data such as projection angle is limited or there are opaque objects in the tested field is discussed theoretically and experimentally. An orthogonal projection sampling method has been proposed for optical tomography in the case of severely incomplete data. And some comparative numerical simulations results of traditional sampling method and the new method are given.
Self-diagnosis and self-repair using hollow-center optical fiber in smart structure
Author(s):
Hong Yang;
Baoqi Tao;
Hao Qiu;
Dakai Liang
Show Abstract
Monitoring damage and repairing crack are the important problems in composite materials applications. In this paper, the method of self-diagnose and self-repair composite structures using hollow-center optical fiber filled adhesive is put forward. Based on this change, the measure method and experimental research of self-diagnose for the rupture location in composite structures are also put forward. To compare characters, experiments of composite with or without embedded optical fiber are performed. A general experimental system for self-diagnose and self-repair is given as an example. The key research issue is to diagnose the location of damage, to repair the crack and to compare the influence with or without embedded hollow-center optical fiber.
New inverse computation for optical-absorption coefficient in semiconductor material
Author(s):
Jianxin Zhu
Show Abstract
In this paper, for an inhomogeneous material in which the thermal conductivity is varied as a function of depth, we propose an efficient method to inversely compute the depth distribution of optical-absorption coefficient by the surface temperature of the material. The results of inverse computation by a group of surface temperature data show that some more accurate optical- absorption coefficients can be obtained.
Optical measuring method of rail wear
Author(s):
Xinmin Qi;
Juning Zhou;
Gongxin Yu;
Futai Zou
Show Abstract
This paper synthetically analyzes several kinds of optical measurement methods of rail wear. A new measuring method and its systematic structure, which realizes automatic measurement of the wear on rail profile, was emphatically elucidated. It was implemented by means of adopting a kind of positive sensitive photoelectric detector PSD, and based on the principle of optical triangle measurement, and using stepping motor for scan and controlled by micro-processor. It provides a new measuring method for monitoring and analyzing the state of railway track- rail and ensures the safe of railway.
Application of holographic interferometry in engineering fracture mechanics
Author(s):
Xiaohai Zhang;
Gongxin Yu;
Xinmin Qi;
Lihua Yuan;
Futai Zou
Show Abstract
Stress corrosion damage has a great proportion in modern machine engineering. The danger resulted from it is because corrosion crack is fine and not easy to be found by eyes. Therefore, it's important to study stress corrosion fracture in the field of engineering fracture mechanics. In this paper, the real-time method and double-exposure method in holographic interferometry are used to monitor and measure crack extension procedure in high-strength steel placed in corrosion environment, and record holographic interferogram. The test results indicate that this method can display clearly change procedure of strain interference fringes at crack-tip, determine stress corrosion fracture starting point of stress corrosion and KISCC. Compared with other methods, it has obvious advantages.
Optical tomography technique for measurement of 3D asymmetric temperature field
Author(s):
Lihua Yuan;
Gongxin Yu;
Xinmin Qi;
Juning Zhou
Show Abstract
A 3D phase object reconstruction is usually studied by using optical tomography. In this paper, the reconstruction for the 3D asymmetric temperature field is studied using the convolution backprojection algorithm by means of computer simulation. It proves that the algorithm is feasible and accurate. Based on the computer simulation, reconstruction of a 3D asymmetric temperature field is realized by using the algorithm to deal with speckle photography.
Using Hopfield neural network and 2D evolutionary operators to detect image edge
Author(s):
Xiaoqin Yang;
Ming Li
Show Abstract
This paper proposed an edge detection method using Hopfield neural networks and 2D evolutionary operators. The algorithm maps a detected image into a Hopfield neural network in such a way that each pixel corresponds to a neuron, and utilizes a population of Hopfield neural networks simultaneously. Different Hopfield neural networks have the same weights but begin to update with different initial neuron output states. In order to resolve the local minimum problem inherent in Hopfield neural networks and enhance the exploitation ability of evolutionary operation in extreme large search space, the dynamic equation of Hopfield neural network and 2D evolutionary operators are carried out alternatively during network's update procedure. The experiments have illustrated its good performance.
3D profile reconstruction using optical fiber Fizeau interferometer
Author(s):
Xiaohong Sun;
Hai Ming;
Wei An;
Li Duan;
Zhongcheng Liang;
Jiangping Xie
Show Abstract
In this article, a new method is introduced to reconstruct 3D profile from the 2D interferogram of Fizeau Interferometer. By using matrix optics, the interferometric mechanism is analyzed. On this bases, the relationship between the interference pattern and 3D profile is built up by fringe tracing of two interferograms of the object to be tested at two places with a certain separation. Depending on the relationship, the data profile are figured out and the 3D profile is obtained with the aid of computer.
Optimal design of effective viewing field and structure layout of a two-CCD vision sensor
Author(s):
Shuhua Yan;
Haibao Lu;
Weihong Zhou;
Wusheng Luo;
Huayong Yang
Show Abstract
Based on the math-model of coordinate measurement of the two-CCDs vision sensor, which is established in this paper, the relationships among the coordinate measuring precision, the effective viewing field, the structural parameters of this sensor and the parameters of CCD itself are analyzed. In the meantime, the optimal structure layout is performed by means of computer simulation. And the simulation results show that the optimal layout of the two-CCDs vision sensor is symmetric structure.
Modeling of ballistic coordinate measurement system of CCD optic target
Author(s):
Wusheng Luo;
Haibao Lu;
Tao Xu;
Zhifeng Chen
Show Abstract
In this paper the ballistic measurement method of little-bore pill of light arms is discussed in theory, and the coordinate measurement model of CCD optic target is set up. This measurement model is different from conventional measurement model in that it is not simply regarding the pill as a point target, but also considering fully the gesture of the pill and continuous image procedure. So this model is of much significance in improving the measurement accuracy of the CCD intersection measuring system.
Temperature field measurement of plasma stream during rapid sprayed tooling
Author(s):
Jiangcheng Fang;
Haiou Zhang;
Guilan Wu;
Yanxiang Chen;
Pengju Xue
Show Abstract
Rapid tooling by plasma spraying is one of the important tasks in rapid prototyping and manufacture technology, stream temperature affects directly on the melting state of powders and the quality of sprayed tooling during spraying. Combining with CCD data collection devices and image processing technology, real-time diagnosis of plasma stream with high temperature and high speed, has been realized during spraying in this paper. The collecting principle and collecting methods in the field of high temperature are specially investigated, as well as the experimental system of real-time collection by using CCD cameras is developed. At the same time, fake color image processing is presented to analyze the law of temperature field distribution. The results are important to realize on-line feedback control of stream structure, and to study further on forming quality.
Application of wavelet transform in image measurement
Author(s):
Qixiang Zhu;
Jiyou Xu
Show Abstract
The sense and characters of wavelet transform (WT) in the image measurement are introduced. The effective functions and methods for image edge detection are discussed. The simulation on the computer for image edge detection and geographic center calculation of airplane image with different image mistiness and background noises are given, and it demonstrated the foreground of application of WT in the image measurement.
Specular enhancement and reduction effects in laser scattering from random rough surfaces
Author(s):
Yi He;
Jian Wu;
Chunping Yang
Show Abstract
The phase properties due to single-scattering from two- dimensional slightly random rough surfaces are presented. Much attention is paid to the intensity statistic in the specular direction, and it is shown that the specular intensity can be enhanced and reduced according to the phase properties. These effects are termed phase-related specular enhancement (PRSE) and phase-related specular reduction (PRSR). Several rough surfaces fabricated in the laboratory are used to demonstrate the theoretical analyses, and quite good coincidences are obtained.
Application of real-time holographic method to the microcrack nucleation process study
Author(s):
Bingheng Xiong;
Zhengrong Wang;
Xiaoxu Lu;
Liyun Zhong;
Yongan Zhang;
Canlin She;
Zhaoyong Xu;
Runhai Yang;
Jinming Zhao;
Peilin Li;
Peizhong Hua
Show Abstract
The fracture process of uniformity solid is simulated by a series of transparent specimen in this study in order to discover relationships between the micro-crack nucleation process and the surrounding stress field. A real-time holographic interferometry is used to record the stress fields and its variations in the specimen while the wave-forms of ultrasonic emission stimulated by the micro-cracks are recorded by a transient automatic wave- form recorder to determine the time, location and intensity of the micro-cracks. The development process of fracture can be visualized clearly by this real-time holographic interferometry. The initial experimental study has brought some phenomena worthy of study. This method provides a powerful new approach for experimental mechanics and seismological research.
3D reconstruction approach in neurovision system
Author(s):
Yingen Xiong;
Haifeng Hu
Show Abstract
In this paper, a new 3D reconstruction approach for 3D object recognition in neuro-vision system is presented. First, a phase based stereo matching using Hopfield neural network approach is presented. The stereo matching problems are treated in frequency domain by using local phase, instead of matching feature or texture of images, the stereo matching process is performed by using local phases of left image and right image in stereo image pair. By using the windowed Fourier transform, the windowed Fourier phases can be calculated. Through the variable window Gabor filter, the local phases of image can also be obtained. The Hopfield neural network is adopted to implement the stereo matching process. A suitable architecture of neural network is established, so that the computation can be implemented efficiently in parallel. A suitable matching function is created by using the local phase property. The energy function for neural network is constructed with satisfying some necessary constraints. The stereo matching process then is carried to find the minimum energy corresponding to the solution of the problem. Second, a 3D object reconstruction neural network is constructed by using BP neural network. So the 3D configuration and shape can be reconstructed by this neural network. With multiple neural networks the 3D Reconstruction processes can be performed in parallel. The examples for both synthetic and real images are shown in the experiment, and good results are obtained.
Absolute phase measurement of linear integer unconcerned phase maps
Author(s):
Jingang Zhong
Show Abstract
A procedure for the measurement of absolute phase values is presented and is used to measure the 3D shape of object with discontinuous height steps. This procedure is based on the linear integer unconcerned phase-maps. Linear integer unconcerned phase-maps are obtained by changing the projecting angle of grating or grating orientation. Experimental results for two kinds of projection optics are presented that demonstrate the validity of the principle.
Optical emission diagnostics of glow discharge plasma for the carbon nitride growth process
Author(s):
Wei Yu;
Shu-Fang Wang;
Xiao-Wei Li;
Lianshui Zhang;
Guangsheng Fu
Show Abstract
In this paper Plasma diagnostics are performed during dc glow discharge plasma-enhanced chemical vapor deposition of carbon nitride thin films using optical emission spectroscopy. The influence of the experimental parameters such as percentage of H2, discharge current and total gas pressure on the emission intensities of the excited species in the plasma is investigated. Based on these results, the excitation mechanism of these species is discussed to gain understanding of the influence of the experiment parameters on the deposition process.
Optical emission study of the plasma plume dynamics during excimer laser ablation of carbon in nitrogen atmosphere
Author(s):
Guangsheng Fu;
Wei Yu;
Shu-Fang Wang;
Xiao-Wei Li;
Lianshui Zhang;
Li Han
Show Abstract
In this paper, the optical emission spectroscopy (OES) is used to study the plasma plume dynamics during XeCl laser ablation of carbon in nitrogen atmosphere. The optical emission spectrum of the plasma is mainly continuous emission near the target in its early formation stage. The discrete spectra can be detected 20ns later and reach the maximum at about 60-100ns. The temporal and spatial evolution of such characteristic peaks as C, C+ and C2 emission lines exhibit different features. The OES results show that the plasma processing dynamics during excimer laser ablated carbon target is :the plasma is produced during the carbon absorbing the laser energy, the particles in the plasma continue their collision process after the laser pulse being over, which make the plasma ionized efficiently, and then the plasma continue expanding, declining and quenching. The creation and evolution mechanism of the active species is also discussed.
New method analyzing laser Doppler effect based on the conclusions of laser speckle technology
Author(s):
Xin Hong;
Yuchi Lin;
Meirong Zhao
Show Abstract
For the first time, time varying speckle analysis is made in the differential structure and time-space correlated function has been deduced, in which the relationship between Doppler frequency shift and speckle time correlated function is got. The traditional method can obviously analyze the Doppler frequency shift of the single particle tested, which is suitable for the condition of fluid measurement, while the signal is Doppler burst. Different from it, for the solid scattering surfaces, signal is similar to the continuous one and signal losing happens randomly due to the surface structure. Superior to the traditional one, our analyzing method connects the Doppler frequency shift with the scattering field, which has the advantage for the analysis of the signal losing.
Several key techniques in the PIV system
Author(s):
Hongwu Tang;
Yong Yang;
Youren Xu;
Xinling Gao
Show Abstract
Through improving the existed PIV system, this paper did not only design the Online Adjustable Digital Pulse Synchronizer and combine with the image intensifier but also program the frame capture software using image card based on PCI bus. The low cost PIV system was built and applied into ship model experiment, and the preferable result was obtained.
Rapid inspection method of an O-E receiver
Author(s):
Yao Nan;
Linmiao Xu;
Xuanjun Jia;
Zhaojing Yang
Show Abstract
For the first time, the rapid inspection method of an O-E receiver based on second-harmonic is proposed for measuring 1.064 micrometers and 0.91 micrometers laser pulse with duration of about 10nm. By comparing the two waveforms from a pulse of laser, we achieve more than 0.6% relative error of pulse-width. The opto- electronic receive have inspected come into use for measuring laser waveform. The measurement uncertainties of ratio of integration area to peak voltage of the laser waveform is 0.6%. It is shown that the ratio is an important parameter for evaluating the accuracy of laser waveform, in contrast, the transient time invariance and linearity of opto-electronic detector is verified.
Multichannel correlation recognition method of optical images
Author(s):
Hongxia Wang;
Junfa He;
Honghui Sun
Show Abstract
In this paper a multi-channel real-time hybrid joint transform correlator is proposed. In this correlator, the computer control is used to divide the screen into several equal size windows, reference images of the windows are all the same one and object images are adopted from different frames of image sequences by CCD, twice Fourier transforms of every channel images are realized by using hololens array. Areas of LCLV and the output light energy can be used effectively. The correlation performance can be improved.
New type of diode-pumped cavity-dumping laser
Author(s):
Fei Chen;
Yujing Huo;
Shufang He;
Lichun Feng
Show Abstract
By combining the techniques of AO (acousto-optic) Q-switching and EO (electro-optic) cavity-dumping, a new type of diode-pumped nanosecond pulsed laser was proposed for the first time. The Q- switched pulses at 1.06micrometers with a peak power of 5.02kW and a pulse width 3.1ns pumped a 1W laser diode on the Nd:YVO4 microchip at the 1kHz repetition rate were obtained. The temporal characteristics of the pulses were analyzed numerically. The experiment results are shown to be in good agreement with theoretical predictions.
Testing of a semiconductor laser integrated system with CCD camera
Author(s):
Junfeng Lu;
JingJuan Zhang;
Wenxi Liang;
Rui Liao
Show Abstract
A diffractive optical element is designed and fabricated to improve the characteristics of the divergence angles of a high- power semiconductor laser. In this paper, the performance of an infrared illuminating system integrated by the diffractive optical element and a semiconductor laser is tested. The images of the infrared illuminating system are collected with the CCD camera and processed by a laser-beam analyzer. In the same time, the picture of three dimensions intensity distribution and the curve of the intensity distribution of any section of the laser beam can be shown clearly. With various characteristics of the laser beam being analyzed, the data of the visual angle in the system is consistent with the design requirement excellently. The experimental result proves that the diffractive optical element obviously ameliorates the divergence angle of the semiconductor laser. It can make the ellipticities of the illuminating faculas less than 1.5 in a propagating distance from 40 meters to 100 meters. This measuremental method can not only present the quantitative analysis, but also be taken a real-time monitoring control.
Application of optical fiber sensors embedded into braided composites
Author(s):
Rui Huang;
Shengfang Yuan;
Baoqi Tao
Show Abstract
Braided composites have advantages over conventional ply composites, which have limitation of brittle interlaminar. They are the hotspot of advanced material research in recent years. Although 3D braided composites have good performances, people do not know enough about them, whether in depth or in extent. In this paper a method in which optic fiber sensors embedded into 3D composites are used to study 3D braided composites is introduced. The braiding process of optic fiber sensors, optic performances of optic fibers are studied. Several kinds of optic fibers are used. Girder form structures with embedded optic fibers are braided through four-step method and processed through Mold Pressing. Some special measures are taken to prevent damage of the optic fibers. Measurement of some performance parameters of optic fibers shows little changes of those parameters before, after optic fibers being braided into the structures, and after the molding process. A polarimetric type of optic fiber sensors is designed for measuring strain in braided testpieces.
Time-resolved spectra studying of oil pollution in water by laser-induced fluorescence (LIF)
Author(s):
Jie Liu;
Changqing Yu;
Jiaze Li;
Jixiang Yan;
Baohua Feng;
Zhiguo Zhang;
Xiulan Zhang
Show Abstract
A new method of remote sensor of micro amount oil in water by laser induced fluorescence is presented. In the detecting system, a MODEL YAG571C pulsed triplicated laser (Continuum Corporation of U.S.A.) With wavelength of 355nm, pulse duration of 35ps, pulse energy of 3mJ was used as exciting source. Using multi-track spectrograph as the detector, a computer as the data processor, 355nm laser as the master trigger which contact the SRS-DG535 four channel digital delay/pulse generator, we have obtained fluorescence lifetime of some aromatic pollution materials in water and relevant 3D (time-wavelength-fluorescence intensity) fluorescent diagrams. By analyzing the spectra property, it is possible to discriminate the oil pollution types.
Technology of differentiating laser pulses based on wavelets
Author(s):
Zhengxun Song;
Zhen Hu;
Lixin Liu;
Yisong Dai
Show Abstract
In this paper, according to the relation between wavelet transform maxima (or zero-crossings) and signal abrupt change point, it is studied that the solution differentiating constant width laser pulse from others with noises or disturbance in the systems working in atmospheric channels.
Application of DSP in the optimal control of APD detectors
Author(s):
Zhengxun Song;
Zhen Hu;
Hongmei Xu;
Dianren Chen
Show Abstract
The control of APD is complicated in the laser system working in atmosphere channels. In this paper the control solution with DSP as center is studied. The real time and intelligent operation of APD is realized. So better applications are obtained in the actual system.
Grating displacement sensor in which the grating line is subdivided directly by CCD instead of subdividing the moire fringes
Author(s):
ShuRong He;
Zongyang Xiao;
Zhuang He
Show Abstract
Different from the traditional way of subdividing the moire fringe that needs complex subsequent circuits, we adopt a linear CCD array to subdivide the grating line directly. Because of the CCD's high sensitivity, consistency and the amount of pixels, the interval between two neighboring lines of the grating can be measured and the subdivision factor is up to thousands of times. Therefore, our device can attain high resolution with limited cost. The circuit is also much simpler than before since CCD driver itself completes the subdividing and digitizing functions. The practical device's precision is better than 0.1 micrometers and the linearity is better than 0.99.
Theory of the variable coordinate transformation systems in the framework of Wigner algebra
Author(s):
Dayong Wang;
Avi Pe'er;
Adolf W. Lohmann;
Asher A. Friesem
Show Abstract
The propagation law of the Wigner distribution function in the first-order non-orthogonal optical systems is described by using the linear canonical transform integral. The Wigner matrices for the usual optical components (free space, spherical and cylindrical lenses, and linear phase filter) are presented in four-dimensional phase space domain. Then with Wigner algebra, we analyze basic and more general optical configurations for performing a set of linear unitary coordinate transformations. These configurations are comprised of refractive spherical and cylindrical lenses that are readily available.
Femtosecond Z-scan measurements of nonlinear refraction in second-harmonic-generation crystals
Author(s):
He Ping Li;
Chan Hin Kam;
Yee Loy Lam;
Wei Ji
Show Abstract
The refractive nonlinearity is measured in several nonlinear optical crystals using the Z-scan technique with femtosecond pulses at 780-nm wavelength. The crystals studied include KTiOPO4, KTiOAsO4 (beta) BaB2O4, LiB3O5 and LiNbO3:MgO, which are extensively used for ultrashort- pulse second-harmonic generation and optical parametric oscillation. The nonlinear refractive index n2 in these crystals is determined to be in the range from 10-16 to 10-15 cm2/W. No two-photon absorption is observed. The experimental results are compared with two-parabolic band model for the bound electronic Kerr nonlinearity. It is found that the measured n2 values in (beta) BaB2O4 and LiB3O5 are one order of magnitude smaller than those of LiNbO3:MgO, KtiOAsO4,KtiOPO4, which is in agreement with the theoretical prediction.
Flaw detection in a partially clamped plate using comparative DSPI
Author(s):
Cho Jui Tay;
Huai Min Shang;
Chenggen Quan
Show Abstract
The paper presents a method to determine defects on a partially clamped plate using comparative digital speckle pattern interferometry (DSPI). The flaw locations are determined using fringe compensation. In flaw detection of a partially-clamped plate which contains a centric flaw, overcrowded fringe pattern is observed. When fringe compensation is applied, the overcrowded background fringes are removed leaving only fringes indicating the defective region. The results in this study show that the proposed method is effective in detecting both the location and size of the defects. Partially-clamped square plates of sides 80mm which contain centric circular flaws are loaded by incremental pressure and the results show that comparative DSPI is capable of flaw detection. Theory of the method and experimental results are presented.
Multiple-reference-light low-coherence interferometer
Author(s):
Yan Zhang;
Manabu Sato;
Naohiro Tanno
Show Abstract
Optical coherence tomography (OCT) is a powerful technique for imaging the random scattering medium. Resolution improvement is an important task in the OCT. A novel low coherence interferometer (LCI) in which three reference mirrors are used to generate reference lights is proposed for obtaining higher resolution. The output signal of this LCI is a superposition of interference of signal light with three reference lights. Through adjusting the relative intensities of reference lights, the width of the axial point spread function for the LCI can be reduced, then the resolution of the LCI will be improved. The influence of fluctuations of wavelength and mirror separation on the resolution improvement are investigated. It is expected that this new approach may provide an effective and useful technique for optical measurement.
Nondestructive testing method of crystal surface defectiveness
Author(s):
Ekaterina V. Zhukova
Show Abstract
Article is devoted to a not destroying method of analysis of crystals surface quality for a vacuum ultra-violet range. The registration of absorption spectra of color centers located in a thin near-surface layer of a crystal with the help of a method of attenuated total reflection spectroscopy allows to visualize defective structure layer formed after machining.
Shadow moire profilometry by frequency sweeping
Author(s):
Lianhua Jin;
Yukitoshi Otani;
Toru Yoshizawa
Show Abstract
The frequency sweeping technique is proposed to measure the shape of objects with discontinuous height steps and/or spatially separated surfaces, which have been impossible to measure with conventional shadow moire topography. By controlling the amount of the rotation angle of the grating, the spatiotemporal moire patterns are produced with different contour intervals. The Fourier transform technique has been applied to analyze these patterns and obtain the temporal carrier frequency in which the height distribution of the object is involved. Experimental results show the validity of this method.
Surface characterization by surface plasmon resonance technique
Author(s):
Simanchalo Panigrahi;
Nikunja Behari Das;
Aseel K. Hassan;
Asim K. Ray
Show Abstract
Metallic gold (Au) film of approximately 45nm thick was deposited on the glass slide by vacuum evaporation method under the vacuum 10-6 Torr. Surface plasmon resonance (SPR) curve was taken in the form of reflected intensity Rp variation as a function of the angle of incidence (theta) for the three layered (glass-Au-air) system and the resulting SPR curve was well fitted by Fresnel's theory to find thickness and optical constants of Au film. The organic overlayers of tetra-undecyl-tetra p- nitrophenylazocalix(4) resorcinarene (Azo 1) compound was deposited by spin coating method. SPR measurements were taken in air as well as in pure water, for an overlayer containing Axo 1 spun on Au coated slides. The large change in the refractive index of water 1.33 as compared to that of air 1.00 causes large shifts in the SPR resonance angle (theta) SPR. The exact determination of the optical parameters of a organic film can be possible by varying the dielectric medium interfacing the overlayer. SPR data for both media used throughout this work were fitted to Fresnel reflection theory for a four layered (glass-Au-Azol-air or water) system. By varying the Azo 1 film thickness during the fitting procedure different solutions have been obtained for the film dielectric constant and hence its refractive index. The refractive index versus thickness for both media were plotted and from the intersecting point of the two curves an exact solution has been found which gives film optical parameters of organic (Azo 1) overlayers.
Synthesis of low-coherence sources for optical coherence tomography
Author(s):
Yan Zhang;
Manabu Sato;
Naohiro Tanno
Show Abstract
The optical coherence tomography (OCT0 is a novel imaging technique for producing high-resolution cross-sectional images of the internal microstructure. Resolution improvement is an important task in the OCT. A new approach is proposed for achieving shorten coherence length by combining several low coherence sources to improve the resolution of the OCT. This optimization synthesis problem belongs to solving an inverse source problem. An optimization algorithm is used to select the parameters of sources for decreasing the effective coherence length and inhibiting side lobe simultaneously. Computer simulations are presented to approve our method. By combining three light sources, the coherence length can be reduced to 57% of the smallest one of a single source used and the side lobes are lower than 5% of the center packet.
Phase transformation studies of ZrO2 in Al2O3 using laser Raman spectroscopy
Author(s):
Tan Kha Sheng;
P. Ramalingam
Show Abstract
Raman Spectroscopy was used as an effective phase characterization technique in material systems containing particle dispersions of the tetragonal and monoclinic polymorphs of zirconia, each of which yields a unique spectrum. A preliminary investigation in the study of phase transformation in partially stabilized MgO- ZrO2(PSZ). The results and analysis of this material under applied pressure is presented here.
Practical 3D computer vision techniques and applications in measurement and NDT
Author(s):
Y.Y. Hung;
L. Lin;
Huai Min Shang
Show Abstract
This paper describes two computer-aided full-field optical techniques for measurement of surface shapes, inspection of surface quality, and nondestructive flaw detection. The first technique is for diffuse surfaces and the second technique is for specularly reflective surfaces. The technique for diffuse surfaces involves projecting onto the surface a computer- generated fringe pattern, whereas the technique for specularly reflective surfaces involves reflecting the fringe pattern from the mirror-like surface. In both techniques, the fringe pattern is perturbed in accordance with the object surface with fringe- phase bearing information on the depth (for diffuse surfaces) or the slope (for specularly reflective surfaces) of the surface. The fringe-phase is determined by a phase extraction algorithm using digitally-controlled four-frame phase-shifting, and the relationship between the fringe-phase distribution and the depth/slope is obtained by calibration. The techniques are applicable in an industrial setting and can be fully automated.