Proceedings Volume 7160

2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications

Shenghua Ye, Guangjun Zhang, Jun Ni
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Proceedings Volume 7160

2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications

Shenghua Ye, Guangjun Zhang, Jun Ni
View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 13 January 2009
Contents: 12 Sessions, 111 Papers, 0 Presentations
Conference: International Conference of Optical Instrument and Technology 2008
Volume Number: 7160

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7160
  • Session 1
  • Session 2
  • Session 3
  • Session 4
  • Session 5
  • Session 6
  • Session 7
  • Session 8
  • Session 9
  • Session 10
  • Poster Session
Front Matter: Volume 7160
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Front Matter: Volume 7160
This PDF file contains the front matter associated with SPIE Proceedings Volume 7160, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Session 1
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Interference fringe analysis using wavelet transform
Takamasa Suzuki, Ryo Kiyohara, Mika Ichikawa, et al.
Fringe analysis methods that employ wavelet transform are described. The performances of the methods are examined from the viewpoints of required calculation time and accuracy. Further, accuracies of calculations performed using linear and logarithmic scales in wavelet transform are compared. Experimental results show that wavelet signal processing is effective in measuring profiles having large and gradual asperities.
Hybrid regularization restoration for adaptive optics image
Bo Chen, Ze-xun Geng, Jun Shen, et al.
The performance of high-resolution imaging with large optical instruments is severely limited by atmospheric turbulence. Adaptive optics (AO) offers a real-time compensation for turbulence. However, the correction is often only partial, and image restoration is required for reaching or nearing to the diffraction limit. In this paper, we consider a hybrid Curvelet-Fourier regularized deconvolution (HCFRD) scheme for use in image restoration problems. The HCFRD algorithm performs noise regularization via scalar shrinkage in both the Fourier and Curvelet domains. The Fourier shrinkage exploits the Fourier transform's economical representation of the colored noise inherent in deconvolution, whereas the curvelet shrinkage exploits the curvelet domain's economical representation of piecewise smooth signals and images. We derive the optimal balance between the amount of Fourier and Curvelet regularization by optimizing an approximate mean-squared error (MSE) metric and find that signals with more economical curvelet representations require less Fourier shrinkage. HCFRD is applicable to all ill-conditioned deconvolution problems, its estimate features minimal ringing, unlike the purely Fourier-based Wiener deconvolution. Experimental results prove that HCFRD outperforms the Wiener filter and ForWaRD algorithm in terms of both visual quality and SNR performance.
Three-dimensional angle measurement based on auto-collimation and moiré fringe
Sheng Cai, Shuang Liang, Yan-feng Qiao
A method for small three-dimensional (3D) angle measurement based on auto-collimation and moire fringe is proposed and analyzed. A right-angle prism is used as the indicator of angle change. The inclined plane indicates the pitch and yaw angles and roll angle in indicated by the rib which is the intersection of two right-angle sides. Pitch and yaw angles measurement are implemented by auto-collimation based on reticule and roll angle measurement is measured based on moire fringe. Roll angle measurement is separated from pitch and yaw by using two light sources with different frequencies. Any small change of pitch and roll angles will induce the shift of the reticule image after reflecting by inclined plane. And any small roll angle will induce a change in moire fringe width that is generated by scale grating image which is reflected by the prism and index grating. The math model of this method is built up and error analysis is presented. The theoretical calculation results show that the proposed method is feasible and can achieve high accuracy.
A study of the laser power online detecting
Qiue Zhang, Rong Zhang, Yongzheng Li
This article introduced a fundamental of new intelligent instruments. It can be used in laser power online detecting. Based in this theory, we have made a new intelligent mini-power meter. The device adopt SPCE061A MPU to control and process the all detected data, Its CPU core is used 16-bits MPU, it is a perfect unit in industry field. It can process complicated digital signals. Its detecting parts adopt high-speed responding and high-sensitive photoelectric dynatron 3DU13 to detecting the beam's output. It respond spectrum is from 0.4 to 1.1µm, can detect any other laser source's online detecting. Which locate in this spectrum range, optical design is made up of 45 degrees high reflect device and dark body scattering structure. The detector receive a little scatter light, use on-chip ADC to sampling the detector's output. By subsection, insert value linearity, proportion calculate to beam's output powers. And then real-time to displaying by LCD. It can communicate to PC by RS232. By communicate to upper instrument and others, the users can use detected data to achieve laser power's closed-loop control, to control laser source's real time output correctly and calibrating by itself. This mini-power meter need use standard power meter to calibrate in installing, after this process, the device can detect laser power's output from 1 to 200 watts correctly. It error is less than 5 percent.
Measurement of single mode fiber non-circularity based on image processing
Shaorong Xiao, Hen Hu, Xiaoli Mao, et al.
Method of computer digital image processing was utilized to measure non-circularity of single mode fiber. The two end faces were polished, the faces come into plane, and which are perpendicular to fiber axis. Laser beam was thrown on one end of the fiber, and an inerratic spot was formed from light beam put out at another end of the fiber. The spot was shot by a digital camera with 5.1x106 pixels. The image was processed with a computer. The process includes full color picture being translated into gray one, contrast enhancement, median filtering, and picking-up contour line. The every different three points on the contour line were taken out to determine one circular radius, average of many radiuses was calculated, The maximum radius and the minimum radius are picked out to calculate the fiber no-circularity in according to definition. Visual C++ and Matlab were used to programme. The results of experiment show that measurement precision is independent of the sampling number, but dependence of gray value, and average standard deviation is about 0.03%.
Session 2
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Novel measurement of Mueller matrix for cells
Yubo Li, Wenjian Jia, Ruoyu Chen, et al.
In this work, we propose a method to measure the Mueller matrix of biological tissues rapidly. Firstly, the effect of biological tissues on the incident light can be represented as absorption, phase retardance and depolarization. This paper defines four parameters as absorption coefficient, phase retardance coefficient, depolarization proportion and azimuth of incident light, respectively. Secondly, we decompose the incident light into two parts: one is totally depolarized, the other is absorbed and its phase is retarded. The two processes are characterized by two corresponding Mueller submatrixes. Then two Mueller submatrixes are derived based on the relation between the Stokes vectors of incident light and output light. Moreover, on the basis of a linear combination of the two Mueller submatrixes, we obtain the Mueller matrix of biological tissues, which contains the unknown parameters. Lastly, we employ the pellicle cell of magnolia for the sample and acquisition of it's polarization images. Then this paper applies the method to construct calculation model from the image data. And just 6 intensity measurements are needed to calculate the four parameters.
A detection and control method of resin liquid-level of stereolithography apparatus
Yiqing Wang, Wanhua Zhao, Leping Shi, et al.
A set of laser detecting system for liquid-level with inclination measurement-based high-resolution and a sinking-block device are developed to detect and control the liquid-level of Stereolithography Apparatus precisely. A brightness-variable laser source is adopted to eliminate the computational error of divider, a closed-loop circuit is set to measure the terminal voltage directly which proportional to the output current of PSD, and hence the position of laser beam can be indicated accurately. A sinking-block device is employed to control the liquid level. The precise calibration result of this detecting device indicates that the resolution of the liquid-level detection can reach ±1.5µm. Compared with overflow liquid-level control, this liquid-level control device of sinking-block style can allow the liquid-level wave reduce from ±45µm to ±15µm. This system works stable with the high precision and antijamming ability. It has applied successfully in Stereolithography Apparatus.
Measurement instrument for all-polarization image information based on electro-optic modulation
Yubo Li, Congzhong Guo, Hao Wang, et al.
In recent years, it has been demonstrated that polarization measurement is more informative than intensity measurement. As a result, acquisition and detection of polarized information is applied widely in various fields such as remote sensing, medical treatment and soon. However, most detect applications for the polarized information, and linear polarizer is described as the key device. Therefore, only linear polarized light information can be detected and other polarization is filtered.
Time decay spectrum and the fluorescence detection of NO2
Guiyin Zhang, Yidong Jin
The fluorescence lifetime of the excited NO2 molecules are observed experimentally by the technique of LIF time decay spectrum. The results show that the time decay spectrum presents a property of bi-exponential. This indicates that the fluorescence is composed of two components. One has a long lifetime, while the other has a short one. The short-lived component comes from the radiation of the molecules excited by B2B1←X2A1 transition. And the long one is owing to the radiation of the molecules excited to the high rovibronic levels of the ground electronic state. These levels are correlated with A2B2 state. The deactivation mechanism of the excited molecules is investigated by measuring the variation of fluorescence lifetime versus the sample pressure. The conclusion is that the excited molecules that corresponding to the short lifetime quench mainly by the process of radiation and fast inner conversion. As to the excited molecules with long lifetime, the deactivation process is not only radiation, but also the non-radiation process of collision. At the same time, the optimum-receiving wavelength of 630nm for detection NO2 gas with the technique of LIF is proposed by measuring the dispersive spectrum. Under the condition of standard atmosphere, a detection limit of 6ppb is obtained with the experimental apparatus.
Session 3
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Study on the improvement of overall optical image quality via digital image processing
Cheng-Mu Tsai, Yi Chin Fang, Yu Chin Lin
This paper studies the effects of improving overall optical image quality via Digital Image Processing (DIP) and compares the promoted optical image with the non-processed optical image. Seen from the optical system, the improvement of image quality has a great influence on chromatic aberration and monochromatic aberration. However, overall image capture systems-such as cellphones and digital cameras-include not only the basic optical system but also many other factors, such as the electronic circuit system, transducer system, and so forth, whose quality can directly affect the image quality of the whole picture. Therefore, in this thesis Digital Image Processing technology is utilized to improve the overall image. It is shown via experiments that system modulation transfer function (MTF) based on the proposed DIP technology and applied to a comparatively bad optical system can be comparable to, even possibly superior to, the system MTF derived from a good optical system.
Application of OTF instrument in the fabrication and assembling of aspheric lens
Xiaoxiao Wei, Jianjun Yu
OTF reflects the frequency characteristic of optical system and is the key parameter that evaluates the imaging quality of aerospace optical lens. The aspherics make the optical system simplified in structure with the imaging quality assured at the mean time, however the assembling technology of aspheric optical system is restricted because the fabrication technology is difficult and a lack of testing means. In this paper, means of OTF testing is adopted and a testing frock clamp is designed and processed to test the OTF of aspherics during its fabrication, and the result of test is used to supervise the fabrication until meet its target. During the assembling of the aspheric lens, the source of aberration that affects the imaging, which is used to supervise the next assembling, is analyzed according to the test result of OTF instrument, and test the OTF of re-assembling aspheric lens another time to see whether the result is meet the request, then the assembling will be accomplished. The result of experiment shows that it is feasible to supervise the fabrication and assembling of aspheric optical system by OTF instrument.
Research on technique of measuring space position change of equipment action part
Wei Wang, Shijie Deng, Ping Wang
At present, a large number of electronic machinery and equipment was launched into military or civilian field. Such kind of equipments can rotates and moves precisely under control of micro-electronics device. It is an important task how to measure space position change of the mechanical parts. And it only can be proved by test that whether the space position change value of action parts meted the specification requirements. And the test must satisfy some accuracy requirements. In response to the test demand, we have developed out a system based on of photoelectricity theodolite. The system belongs to non-touched device, it is convenient and precise to use. In large-scale Space position changes with high-precision demand test mission, We think this method is the most feasible so far.
Current transformer based on optical fiber fluorescent thermometry
Danping Jia, Ting Jia, Liang He, et al.
In the paper a review on the potential advantages of optical current transformers points out that it is the technology trend on the development of current transformer. But there are many more difficulties to be resolved, innovative ideas of developing optical current transformers must be strengthened. A high voltage current transformer project based on current thermal effect was introduced, which combined the current thermal effects and the optical fiber thermometry technology. Fiber optic temperature sensor was the earlier and mature product among fiber optic sensors in commercial, current thermal effects technology is more general applied, so the new project has the advantages over other current transformer projects which are now meeting the difficulties hardly to resolve. The relationship between the instantaneous value of measured current and the temperature rise was deduced, and the mathematical model of the current transformer was established. By use of the mathematical model, in theory, the instantaneous value of current can be tracked by the temperature output of sensor accurately, so that it can be used to measure instantaneous value of current. The technical data and features required of the main devices and components can be provided by use of the mathematical model for technical design of the project, simulation method and experiment tests were used to prove the availability.
Session 4
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Orientation function of optical mouse realized by digital speckle correlation method
ZhiQiang Zhen, ZhengXin Tang, Haitao Yan
Used digital speckle correlation method (DSCM) to realize orientation function of optical mouse is researched. The experiment is designed to obtain the dynamic speckle patterns which are shot by CCD, Then the DSCM is used to process the sequential images and also the experiment is simulated. The experimental results show the DSCM can confirm orientation function of the optical mouse, and have a good agreement with the simulation results, and the resolution we obtained is higher than the resolution of mouse on the market.
Approach for obtaining phase distribution of fringe pattern with complex coefficient FIR band-pass filter
Keyou Jin, Haihua Zhang, Yong Li
Three dimension measurements with projected fringe is the important method of optical 3D sensing. The approach for obtaining phase distribution of deformed fringe pattern is a key technology of this method. In this paper, a new method for obtaining phase distribution of deformed fringe pattern is proposed. In the proposed method, phase distribution is obtained directly by filtering deformed fringe pattern with complex coefficient finite impulse response (FIR) band-pass filter. The detail of this method is expressed as following: Firstly, a FIR low-pass filter is designed whose band width is half of the width of first order spectrum of the deformed fringe pattern. Secondly, the complex coefficient FIR band-pass filter is gained by moving the spectrum of low-pass filter to the position of the first order spectrum of the deformed fringe pattern. Finally, the phase distribution is obtained by filtering the deformed fringe pattern with designed filter and calculating the argument of the filtered pattern. The theory and experimental results are presented. In experiment, compared with FTP, the standard deviation of phase measurement reaches 0.75%. As a result, this approach provides a new way to obtaining phase distribution of deformed fringe pattern.
Determination of atmospheric pressure loading coefficient in Changchun SLR station
You Zhao, Sok Jong, Yong Chol Pak, et al.
The atmospheric pressure loading coefficient describing the effect of air pressure loading on the site coordinates is one of the important factors arising in the precise coordinate determination by modern space geodetic techniques such as VLBI, SLR, GPS and so on. This paper deals with the calculation of the atmospheric pressure loading coefficient of Changchun SLR station by means of a simple empirical approach using 5 years (2001-2005) observation data, and analysis of the pressure loading effect on the station height. The 5-year averaging loading coefficient was estimated to be about -0.5 mm/hPa, and the result indicates that, like the other stations, Changchun station coordinates, especially the vertical component has a close relation with local atmospheric pressure, being very sensitive to atmospheric pressure loading effect. Also analyzed in this paper is the atmospheric "blue sky" effect on the Changchun SLR station height on the basis of the loading coefficient estimates.
ICG fluorescence imaging and its medical applications
Mitsuharu Miwa, Takahiro Shikayama
This paper presents a novel optical angiography system, and introduces its medical applications. We developed the optical enhanced imaging system which can observe the blood and lymphatic vessels as the Indocyanine green (ICG) fluorescence image. The imaging system consists of 760nm light emitted diode (LED) as excite light, CCD camera as a detector, a high-pass optical filter in front of the CCD and video processing system. The advantage of ICG fluorescence method is safe (radiation free), high sensitive, real time monitoring of blood and/or lymphatic flow, small size, easy to operate and cost effective compared to conventional X-ray angiography or scintigraphy. We have applied this method to several clinical applications such as breast cancer sentinel lymph node (SLN) navigation, lymph edema diagnostic and identification of liver segmentation. In each application, ICG fluorescence method shows useful result. It's indicated that this method is promising technique as optical angiography.
Sinusoidal wavelength-scanning interferometer using an acousto-optic tunable filter with double feedback control for real-time distance measurement
Osami Sasaki, Daiki Matsubara, Takamasa Suzuki
Optical path difference (OPD) and amplitude of a sinusoidal wavelength-scanning (SWS) are controlled with double feedback control system in an SWS interferometer, so that a ruler marking every wavelength and a ruler with scales smaller than a wavelength are generated. These two rulers enable us to measure an OPD longer than a wavelength. An acousto-optic tunable filter (AOTF) is adopted as a wavelength-scanning device. The frequency of the SWS is 10 KHZ, and the measurement time required to reach a stable point of the control system is about 7ms. The measurement range is from 65 m to 190 m with the measurement error less than 4nm.
Session 5
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Auto-adapted iterative deflection tomography approaching high frequency shock wave field
A new deflection tomography system was put forward and named Auto-adapted Iterative Deflection Tomography (AIDT). It was tested to approach accurate reconstruction of a high frequency field containing shock waves with sufficient projections. A high frequency field was constructed with Gauss and rectangle window functions. It was simulated to project in all directions with angle resolving rate per degree. Two cross projections was selected to simulate reconstructing the model field by AIDT. Then, the number of projections was increased step by step in order to approach the accurate values of the model. All reconstructed results were studied. As a result, all high frequency sections are distorted much. With a few projections, such as two projections, the reconstructed results lost the basic characteristics of the model. With projections increasing, the distortions get lighter and lighter. Near the critical projections, such as twenty-four projections, the reconstructed field becomes similar to the model except some high frequency sections. When eighty-four projections are employed, the reconstructed result is in accord with the model. In this case, the Mean Square Error(MSE) is 0.00003609. But up to one hundred and eighty projections, the reconstructed result almost stopped improving. In this case, the MSE is 0.00003231. As we know, these are most accurate reconstructions to now. AIDT can accurately reconstruct high frequency fields with shock waves.
Unknown orientation views calibration for the improved Fourier transform profilometry
Changku Sun, Tao Wang, Peng Wang
In traditional Fourier transform profilometry, the conversion from phase to height is deduced depending on the supposition that not only are the projector and the camera at the same height above the reference plane, but also their axes must cross at the same point on the reference plane. When these conditions are too strict to be satisfied, a large measurement error will be introduced. An improved optical geometry of the projected-fringe technique is discussed and phase-height mapping formula is deduced in this paper. Employing the new optical geometry, a simple calibration model is developed based on absolute phase extraction and space mapping techniques, which make the environmental parameters is not as critical as before. Furthermore, a virtual space pattern is used to provide the reference points for camera calibration based on Zhang's calibration method. The calibration can be accomplished merely with a planar pattern, which extremely reduce the cost of device and make the process of measurement more convenient. The experiment result shows the good accuracy of the system.
Non-contact measurement of contact wire
Yaxing Yi, Xuemei Ye, Zhongke Li, et al.
The overhead contact system is the power supply unit of the electric locomotive. This article is to introduce our newly developed method to measure the height and pull out value of the contact wire. A carema dolly which can move on railway is applied to bear the weight of the measure equipment; two linear CCD cameras are installed on the dolly symmetrically about the midline of two rails. While the dolly move along the railway, two CCD cameras grasp the image synchronously, and a computer real-time process the images, the height and pull out value can be calculate out from the images.
Coal stack reserves measurement system based on stereovision technology
Xiaoping Du, Yang Zhao
The paper put forward two coal yard reserves measurement technical schemes based on passive stereovision, which adopt travel crane plane scanning structure to measure coal stack cubage accurately with high precision space distance measuring technology and large size image splicing technology. The hardware configuration and measurement method of the system designed in this paper are simple. What is more, the system can improve measurement accurate, predigest operation flow and reduce measurement cost. The system can satisfy the requirements of coal reserve quantity measurement in power plant that the measurement must not affect the coal using on-the-spot and other production activities in coal stack field.
Session 6
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Sub-ppm NH3 sensor for control of de-nitrification process using diode laser spectroscopy
Haitao Gu, Lipeng Liu, Ying Li, et al.
Diode laser absorption spectroscopy (DLAS) has become an important analytical technique for highly sensitive and specific gas concentration measurements as it is reliable, fast and accurate. In this work a diode laser sensor has been developed to monitor ammonia at sub-ppm in 1510-nm region. The system was designed to control the de-nitrification process with selective catalytic reduction (SCR) abatement system. To ensure that NOx is reacted completely and to avoid secondary pollution resulted from ammonia slip, it is essential to monitor emissions of ammonia for controlling the amount of NH3 injection. NH3 concentration is demanded not to exceed 5ppm, preferably 2-3ppm. In order to provide enough sensitivity, the sensor uses DLAS with wavelength modulation as AC detection of absorption line derivatives, at frequencies where the laser noise is reduced, coupled with coherent electronic detection techniques. Experiment results demonstrate that the sensor with the second-harmonic detection shows in-situ, continuous measurements with low detection limit (60 ppb), fast response (<1s) and long-term stability all of which is difficult to obtain with conventional techniques such as wet chemical analysis, non-dispersive infrared (NDIR). In addition, the influence of water vapor on ammonia measurements due to line broadening effects is investigated. A real-time spectrum analysis algorithm is developed. The systematic measurement error is corrected by means of the line width measurements based on fast pattern correlation analysis of second-harmonic line shape. This offers the advantage of accurate NH3 concentration measurement even though the moisture content is above 40%.
The guidance methodology of a new automatic guided laser theodolite system
Spatial coordinate measurement systems such as theodolites, laser trackers and total stations have wide application in manufacturing and certification processes. The traditional operation of theodolites is manual and time-consuming which does not meet the need of online industrial measurement, also laser trackers and total stations need reflective targets which can not realize noncontact and automatic measurement. A new automatic guided laser theodolite system is presented to achieve automatic and noncontact measurement with high precision and efficiency which is comprised of two sub-systems: the basic measurement system and the control and guidance system. The former system is formed by two laser motorized theodolites to accomplish the fundamental measurement tasks while the latter one consists of a camera and vision system unit mounted on a mechanical displacement unit to provide azimuth information of the measured points. The mechanical displacement unit can rotate horizontally and vertically to direct the camera to the desired orientation so that the camera can scan every measured point in the measuring field, then the azimuth of the corresponding point is calculated for the laser motorized theodolites to move accordingly to aim at it. In this paper the whole system composition and measuring principle are analyzed, and then the emphasis is laid on the guidance methodology for the laser points from the theodolites to move towards the measured points. The guidance process is implemented based on the coordinate transformation between the basic measurement system and the control and guidance system. With the view field angle of the vision system unit and the world coordinate of the control and guidance system through coordinate transformation, the azimuth information of the measurement area that the camera points at can be attained. The momentary horizontal and vertical changes of the mechanical displacement movement are also considered and calculated to provide real time azimuth information of the pointed measurement area by which the motorized theodolite will move accordingly. This methodology realizes the predetermined location of the laser points which is within the camera-pointed scope so that it accelerates the measuring process and implements the approximate guidance instead of manual operations. The simulation results show that the proposed method of automatic guidance is effective and feasible which provides good tracking performance of the predetermined location of laser points.
Edge detecting methods and implement on laser peak detection of SLR system
Zhenwei Li, You Zhao, Chong Chen
Highly automation is a direction of Satellite Laser Ranging (SLR). The optical path of the laser in the domestic SLR system often shows instability, which causes errors in the laser orientation and greatly lowers the laser echo rate. In order to improve the laser echo rate, it's essential to calibrate the laser orientation real-timely. Firstly it's requisite to obtain precise pointing of laser beam-peak, whose effective way is to locate the position of the beam-peak which is imaged on the CCD because of the effect of backward scattering. Then the target-missing quantity of the position of the beam-peak is calculated and transmitted to the servo system of the adjustable mounts for calibrating the laser orientation. Using Harris corner detecting algorithm, this paper detects the beam-peak of laser, gives the precise point of beam-peak and lays a foundation for improving the automation of SLR system.
Session 7
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Information extraction method of ultraviolet spectrum measurement of SO2 and NOx
Changku Sun, Shumin Li, Bin Liu, et al.
The measuring principle of SO2 and NOx, which are the main gaseous contaminants in flue gas, is given based on the differential optical absorption spectroscopy (DOAS). And the structure and composition of the measurement system are introduced. In the aspect of obtaining the absorption feature of measured gas, a multi-resolution preprocessing method of original spectrum is adopted to denoise by the signal energy in different scales. On the other hand, the useful signal component is enhanced according to the signal correlation. These two procedures can improve the signal-noise ratio (SNR) effectively. In addition, the origin of the nonlinear factors is analyzed, that is caused by the actual measurement condition. And the polynomial approximation equation is deduced. In the lab, SO2 and NO are measured several times with the system using the data extraction method mentioned above. The average deviation is less than 1.5%, while the repeatability is less than 1%. In the scene of one power plant whose concentration of flue gas has a large variation range, the maximum deviation is 2.31% in the 18 groups contrast data.
Research on human physiological parameters intelligent clothing based on distributed Fiber Bragg Grating
A human physiological parameters intelligent clothing is researched with FBG sensor technology. In this paper, the principles and methods of measuring human physiological parameters including body temperature and heart rate in intelligent clothing with distributed FBG are studied, the mathematical models of human physiological parameters measurement are built; the processing method of body temperature and heart rate detection signals is presented; human physiological parameters detection module is designed, the interference signals are filtered out, and the measurement accuracy is improved; the integration of the intelligent clothing is given. The intelligent clothing can implement real-time measurement, processing, storage and output of body temperature and heart rate. It has accurate measurement, portability, low cost, real-time monitoring, and other advantages. The intelligent clothing can realize the non-contact monitoring between doctors and patients, timely find the diseases such as cancer and infectious diseases, and make patients get timely treatment. It has great significance and value for ensuring the health of the elders and the children with language dysfunction.
Measurements of multi-angle polarization properties of the water-bearing yellow brown soil using multi-band polarimetric imagery in the laboratory
Xiaobing Sun, Jin Hong, Yanli Qiao
It is important for scientific agriculture to observing soil moisture content using remote sensing technique. Optical polarization remote sensing may be applied to soil moisture detection. There is a close relationship between soil surface moisture and its polarization property. The information of soil moisture content can be retrieved quantitatively according to the variation of polarization. In order to investigate the polarization properties of water-bearing soil, the yellow brown soil samples were collected in Hefei, Anhui, and measured in different phase angles under laboratory conditions. The incident angle of unpolarized beam was 40 degrees. The experiments of polarimetric imaging for the soil samples with different moisture content were made. The polarization image data were obtained using the multi-band polarized CCD camera. It was found that the degree of linear polarization (DOLP) of sample was inversely proportional to the viewing waveband. The DOLP increased with an increase of the phase angle before the percent moisture content of the samples reached 30% approximately. The DOLP reached the maximum with an increase of the phase angle when the soil samples were near saturated, saturated and oversaturated in soil moisture content. But the DOLP decreased with a further increase of the phase angle. The results indicate that the polarization properties of near saturated, saturated and oversaturated soil samples present the similar characteristics of Fresnel reflection. Obviously, the multi-angle and multi-band polarimetric imaging measurements for the water-bearing yellow brown soil provide an approach to monitor soil moisture using polarimetric imaging in airborne or satellite remote sensing.
Micro-vibration measurement using self-mixing interferometer based on temporal carrier phase shifting technique
Hui Hao, Ming Wang, Dongmei Guo
A new self-mixing interferometer (SMI) based on temporal carrier phase shifting technique is presented. Self-mixing interference occurs in the laser cavity by reflecting the light from a mirror-like target in front of the laser. Triangular phase modulation of the beam is obtained by an electrooptic modulator (EOM) in the external cavity. The phase of SMI signal coming from the photodetector is extracted by the phase shift demodulation algorithm based on sampling technique. Theoretical analysis and simulation calculations are presented and some errors of this method are discussed. The interferometer is applied to measure the Micro-vibration of a high-precision commercial PZT with an accuracy of <10nm.
Full-field laser vibration measurement in NDT techniques
Kaiduan Yue, Zhongke Li, Yaxing Yi, et al.
Research of Non Destructive Testing (NDT) methodology has developed rapidly in recent years[1][2]. But it is rarely used for small objects such as Micro-electronic Mechanics System. Due to the small size of the MEMS, the traditional method of contact measurement seriously affects the parameter of the object measured. So a high accuracy non-contact measurement is required for optimization of MEMS designs and improvement of its reliability[3][4]. With recent advances in photonics, electronics, and computer technology, a Non Destructive Testing (NDT) laser time average interferometry is proposed in the paper. Laser interferometry has the advantages of non-contact, high accuracy, full-field and fast speed, so it can be used to detect cracks in MEMS. A time average measurement method of digital speckle pattern interferometry is proposed to measure the vibration mode of the MEMS in the paper. According to the sudden change of amplitude of vibration mode, a crack can be measured. With the speckle average technology, high accuracy phase-shift, continuous phase scanning technology, combined with optical amplification technology, the resolution of the amplitude reaches 1nm, and the resolution of the crack reaches 5μm. The measurement system being full-field, the measuring speed of the measurement system can reach 512*512 points per one minute.
Session 8
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Study on activity measurement of [i]Nostoc flagelliforme[/i] cells based on color identification
Yizhong Wang, Jianyu Su, Tiegen Liu, et al.
In order to measure the activities of Nostoc flagelliforme cells, a new method based on color identification was proposed in this paper. N. flagelliforme cells were colored with fluoreseein diaeetate. Then, an image of colored N. flagelliforme cells was taken, and changed from RGB model to HIS model. Its histogram of hue H was calculated, which was used as the input of a designed BP network. The output of the BP network was the description of measured activity of N. flagelliforme cells. After training, the activity of N. flagelliforme cells was identified by the BP network according to the histogram of H of their colored image. Experiments were conducted with satisfied results to show the feasibility and usefulness of activity measurement of N. flagelliforme cells based on color identification.
Research on space coherent laser communications technology
Song Lu, Song Tong, Zhu Yi Feng, et al.
In this paper, we research the laser transmission characteristics in the space channel environment and on which basis, research the overall composition of coherent space laser communication systems and focus on its key technologies, including high-speed outer optical modulation technology, optical phase locking technology, photo mixing technology, optical heterodyne detection and optical signal processing technology, Finally, the article looks for prospects on the development of coherent space laser communication.
Calibration of CNC milling machine by direct method
Abdul Wahid Khan, Wuyi Chen
Calibration refers to the system of quantity value determination of instruments, equipments and test devices according to industrial requirement, based on metrological characteristics. In present research critical parameter which affects the accuracy and product quality of a CNC milling machine, was investigated and quantified by using direct method. These parameters consist of position dependent or position independent parameters, like linear displacement errors, angular errors of linear axes, straightness error of linear axes and squareness error between the axes. Repeatability, lead screw and resolution error of the CNC milling machine were also quantified to provide additional information to the user, because in absence of this additional information a misconception persists causing a major contributor to the inaccuracy and quality of the product. Parameters were measured and quantified by using a laser interferometer and artifacts as working standards under controlled environmental conditions on a manufacturing CNC milling machine. Polynomial regression analyses were carried out for finding the coefficients to predict the errors at each and every desired position which is quite useful for compensation and enhancing the accuracy of a machine system. Machine accuracy detailed chart was also made to assess and assure the accuracy, capability or for accuracy monitoring of the CNC milling machine
Photocatalytic degradation of formaldehyde by diffuser of solar light pipe coated with TiO2 under partly cloudy conditions in Beijing
Yanpeng Wu, Xiaodong Wang, Rendong Jin, et al.
Solar light pipe combined with Photocatalysis to depredate formaldehyde under cloudy conditions in summer were tested in Beijing. The solar light pipe used in the experiment is a straight solar light pipe, which is 550mm long, with diameters of 280mmmm Degussa P25 titanium dioxide ("Degussa", Germany) as photocatalyst was coated on the surface of the emitter of the solar light pipe. The test chamber made up of stainless steel is 0.1m3. The experiment results showed obvious effect on decomposing formaldehyde of solar light pipe combined with Photocatalytic under cloudy conditions. The volume fraction of formaldehyde reduced from 1.0x10-6 to 0.16x10-6 during 35min and the value reduced from 1.0x10-6 to 0.10x10-6 during 60min under cloudy conditions. The experiment showed that Photocatalytic by the radiations of sunlight under sunny conditions also has good effect for air cleaning.
Session 9
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Seepage and settlement monitoring for earth embankment dams using fully distributed sensing along optical fibers
P. Y. Zhu, Y. Zhou, Luc Thévenaz, et al.
A method for seepage and settlement monitoring in earth embankment dams using fully distributed sensing along optical fibres is proposed. A model is developed for simulating and monitoring seepage and settlement systems. This model relates the strains and the temperature changes to the fiber Brillouin gain spectrum in the embankment dam embedding the optical fiber sensors. The model consists of two parts. Submodel 1 addresses the simulation of seepage inside the embankment dam. Submodel 2 relates the measurement of the fiber Brillouin gain spectrum to the changes in temperature and strain inside the embankment dam. Both the changes in temperature and strain during the process are used to reveal serious seepages and settlements occurring inside the embankment dam. The continuously decreasing temperature curve shows an abrupt dramatic increasing rate, which shows that the change is not caused by the temperature of the seepage water but the strain. In this paper, as an example, a model filled with the soil from Yellow River is built and bare optical fibers are embedded under different soil layers near the seepage path. The simulated seepage flows under various flow rates are monitored using the optical fibers and measured by a DiTeSt -STA202 distributed temperature and strain analyzer. A partial settlement within the embankment dam model is observed.
Vibration analysis based on electronic stroboscopic speckle-shearing pattern interferometry
Dagong Jia, Changsong Yu, Tianhua Xu, et al.
In this paper, an electronic speckle-shearing pattern interferometer with pulsed laser and pulse frequency controller is fabricated. The principle of measuring the vibration in the object using electronic stroboscopic speckle--shearing pattern interferometer is analyzed. Using a metal plate, the edge of which is clamped, as an experimental specimen, the shear interferogram are obtained under two experimental frequencies, 100 Hz and 200 Hz. At the same time, the vibration of this metal plate under the same experimental conditions is measured using the time-average method in order to test the performance of this electronic stroboscopic speckle-shearing pattern interferometer. The result indicated that the fringe of shear interferogram become dense with the experimental frequency increasing. Compared the fringe pattern obtained by the stroboscopic method with the fringe obtained by the time-average method, the shearing interferogram of stroboscopic method is clearer than the time-average method. In addition, both the time-average method and stroboscopic method are suited for qualitative analysis for the vibration of the object. More over, the stroboscopic method is well adapted to quantitative vibration analysis.
Displacement measurement with λ/8 resolution based on the bifurcate subcavity modulation effect in a dual frequency laser
Weixin Liu, Shulian Zhang
A novel method for displacement measuring is proposed based on the bifurcate subcavity modulation effect in a dual frequency laser. Owing to the intracavity wave plate, the laser operates on two orthogonally polarized modes. If a portion of laser, channeled into a subcavity by the wave plated, is reinjected back to the resonator, the mode intensities are modulated with a period of a half of wavelength, respectively. And the two modulations behave a 90 degree phase difference, which could subdivide a period into four regions: horizontal polarization, two polarizations, vertical polarization, and no light. In this paper, this subcavity modulation effect is demonstrated experimentally and theoretically. Furthermore, a displacement measurement of the subcavity mirror is developed with resolution up to λ/8, viz. about 79nm at laser wavelength of 632.8nm. The direction discrimination of measuring could also be realized utilizing the sequence of four different subdivision zones. The measuring range, mainly limited by both the splitting frequency difference and the bifurcate subcavity length, could reach tens of millimeters. Measurement results are presented and the corresponding error analyses are discussed. This system has great potential in applying to metrological fields for its simplicity, compactness and high quality performance.
High speed imaging with CW THz for security
Qian Song, Albert Redo-Sanchez, Yuejin Zhao, et al.
Continuous THz wave (CW THz) has been widely used in imaging field. But for security screening such as inspection at the airport, the speed of the imaging calls for an improvement since the former CW image systems which scan point to point could not satisfy. To increase the image speed, we proposed a fast CW THz image system in which a galvanometer is introduced for the first time. The galvanometer makes the coming beam reflected in different angles by vibrating at a certain frequency which can significantly decrease the image acquisition time compare to point scan THz imaging. A big hyperbolic polyethylene lens is also used in the system to collect all the beams on to the target. A Gunn oscillator and a corresponding Schottky diode are the source and detector respectively. The image we get has ideal resolution. And after image processing, the images looked not only clear but also realistic. The system has more practicality because it is designed in reflection geometry instead of transmission geometry. Moreover, the source and detector in our system do not as ponderous as gas laser which has been used in many THz imaging system previously. Example of measurements of weapons concealed behind the cloth and box are presented and discussed. A compact high speed THz imaging system is expectable which will have a widely application in security field.
Metrology of deep trench structures in DRAM using FTIR reflectance spectrum
Chuanwei Zhang, Shiyuan Liu, Tielin Shi
The demand for advanced DRAM technologies with smaller ground rules lead to new challenges for online metrology of high aspect-ratio deep trench structure. In addition to common metrology methods like ellipsometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM), the use of further measurement techniques are needed for advanced node technology. This paper proposes a technique for metrology of critical dimension (CD) of deep trenches formed as capacitors in advanced dynamic random access memory (DRAM) using Fourier-transform infrared (FTIR) reflectance spectrometry. This technique is based on a fast but accurate modeling of the complex periodic deep trench structure, which is represented as a multilayer thin film stack with a combination of homogeneous layers on the silicon substrate using effective medium approximation approach. The metrology problem is solved by an artificial neural network (ANN) and Levenberg-Marquardt (LM) combined algorithm to find the values of the modeling parameters which should produce a best fit to the given measured spectrum. This technique is validated by simulation of extracting geometry parameter of actual DRAM trench structures, and demonstrated to be an adequate approach for the determination of the structure parameters.
Session 10
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Quantitative determination of toxic metals in soil by laser induced breakdown spectroscopy
Jisong Huang, Weidong Zhou, Chaofu Ying, et al.
Laser-induced breakdown spectroscopy (LIBS) is a promising technique for in situ environmental analysis. The potential of this technique for accurate quantitative analysis of heavy metals in soil could be greatly improved by optimized the time delay, laser energy, working distance, et. and by analyzing the results with a procedure which overcomes the problem related to the physical character of soil sample. A LIBS system for soil analysis is reported here. The optimum experimental conditions for quantitatively measurement of Sr and other heavy metals in soil are presented. A new data acquisition and statistical method has been used to analyze the recorded spectra. The precision of this method, in terms of relative standard deviation (RSD), is of 7 % for Sr I 460.73 nm. The calibration curve for quantitative measurement of Sr has been built. From the calibration curves, the detection limits of Sr in soil were determined to be 15.0 µg/g, and are better than the data reported in literature.
Data analysis and processing in EIT system
Ge Kou, Wenjian Chen, Shujun Chen
The method and setup of EIT experimental study are introduced briefly first. Then the EIT data collected under auditory and visual stimuli respectively are analyzed, and the curves of reference data change with different current drive are shown. Meanwhile, auditory and visual EIT data versus reference data and the curve of EIT voltage changes due to two different stimuli of the same subject are given. A comparison is made between EIT voltage changes of human brain due to two different stimuli. A reconstructed image from these data is given. The effect of the number of the iteration and regularization parameter have on imaging quality are discussed in details. At last, a conclusion is drawn that data analysis and processing can help to investigate the activity of human brain.
Precision relative pose estimation at close range using single camera and laser range finder
Hailiang Wang, Maosheng Xiang, Hongjian You, et al.
As in close-range photogrammetry, space resection method is very frequently used in obtaining the exterior orientation data of a single photograph by applying the collinearity equation, but it has relatively poor accuracy in determining the line-of-sight component, especially in the condition the camera has a small field of view (FOV). This paper proposes a new solution for relative pose estimation of a setup consisting of a single camera, a Laser Range Finder (LRF), three optical targets and a array of cube-corner reflectors. These optical targets are installed properly on the target object as control points; the reflectors array is also fixed on the target object to make sure that sufficient signal energy could be returned to the Laser Range Finder. Rotations of the target object produce some errors in the measurements of LRF, so if we want to get the precise data of the line-of-sight component, the two-dimensional position in the array plane must be determined where the signal is returned from. In this paper we develop a method to solve the problem coupling with the pose data obtained from photogrammetry. We derive a new collinearity equation form and improve the one photograph space resection algorithm for the target object pose estimation relative to the camera or LRF. Simulation experiment results show that the algorithm can converge to a precision data during about 3 times least-squares iteration; the accuracy of position data achieve the level of sub-millimeter; and the RMS error of attitude data is less than 50 arcseconds.
Heavy metal content estimation in leaf by spectrum features of plant in De-Xing copper mining area
Fengjie Yang, Guangzhu Zhou, Yulong Pan, et al.
The estimation of heavy metal content in leaf is important to the integration of remote sensing into evaluation the ecological conditions in mining area. In this paper, correlation analysis and multivariable statistical methods were used to build hyperspectral models for the heavy metal (e.g., Cu) estimation with independent variables such as spectral reflectance, derivatives and ratio indices. Results showed that the heavy metals often display effects on plants as they changed plant moisture content, the pigment content, the leaf structure, and so on. Stepwise Multiple Regression Model predicted value and the actual value comparison showed that the model is stable, and the relative deviation about single plant mostly below2%. The first and second order differential spectrums were employed on three kinds of herbs synthesized also, the first order differential model proved better, and its relative deviation is lower than 15%.
Poster Session
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Targets tracking relating method based on fuzzy reasoning and wavelet energy detection
Gang Liu, Yao-wu Shi
Targets tracking methods based digital image are used widely. During the process of multi-targets tracking, when the targets falling in the tracking door are not only one, joint data association is used as a traditional method. But there is so much operation in this method that the need of real time can not be meet. Targets tracking relating method based on fuzzy reasoning and expending Kalman filter is adopted in this paper. Firstly, wavelet energy is adopted to detect targets in the image. The wavelet of bior1.3 is used to decompose image. It is anti-symmetric wavelet and is fit for detecting variational information in horizontal and vertical direction. Because the detected image generally have natural texture background, such as sea, sky, and so on. The targets have high frequency characteristic at horizontal and vertical direction in these images, but the background has high frequency characteristic at one of the two direction. The wavelet energy of targets at two direction go beyond that of background. Then through selecting self-adaptive threshold, targets and background can be divided. By the method of figure centers distance classifying, the figure centers of every target can be calculated. Secondly, Targets figure-center coordinate is detecting through self-adapting figure-center filter. Thirdly, fuzzy reasoning method is used in the progress of data relating. It is easy in engineering application compared with the JPDA arithmetic. In the experiment, after several frames relating, the mean square error of row coordinate reduce from 0.278 to 0.148. The errors of multi-targets figure-center coordinate gradually decrease. The forecast veracity gradually increase.
In-line Calibration of Phase Shifters for Interferometer Measurement
In phase-shifting metrology, the accuracy of phase measurement is directly affected by the phaseshifting error, Accurate calibration of phase-shifter is very important if good measurement results are expected. A new in-line high accuracy phase-shifting calibration method based on Damped-Least-Square algorithm which provides stable convergence and accurate phase distribution is presented. By intercepting a line on the same position from a series of interferograms associating with the phase-shifter's characters and constructing the mathematic model for intensity of the line on each interferogram, the correlative coefficients of the mode's function can be solved, one of which is the wrapped phase. Then the voltage-unwrapped phase curve is obtained through unwrapping technique. Results of computer simulation show a high accuracy after several fast iterations. In addition, taking an experiment for example in our interferometer, the characteristic curve of phase shift over voltage change is presented in the end. Experiment results show it can be an in-line calibration method for phase-shifer in PSI.
Study on broadening the size range in laser particle size measurement by combined spectrum technology
Yong-jie Wei, Wen-chao Li, Bao-zhen Ge, et al.
In laser particle size measurement, the instrument based on traditional Fourier transform structure is disadvantaged in the narrow measurable dynamic size range. So it is hardly to be used to measure broadly distributed particle. The presented technology is based on Fresnel diffraction theory. The formula of combined spectrum technology by detecting signals on coaxial focal planes is educed. In the proposed method, the two lenses are set coaxially and signals are detected on the back focal plane of the first lens and the combined back focal plane of the two lenses. The detected signals are then combined. The data are processed with a no-model algorithm. Thus, the measurable dynamic range can be broadened as no component of the sizer is changed. Experimental results of some samples show that the particulate in the size range of 5 ~ 3500 µm can be measured simultaneously.
The effects of APS star tracker detection sensitivity
Huaxun Zhang, Jie Li
Detection sensitivity is an important parameter of star tracker, which can express detecting limit of the weakest detected visual star magnitude. In this paper, the expressions of APS star detected signal and APS noise are given, so signal-noise ratio (SNR) of star tracker can be obtained. And the detection sensitivity model is obtained from SNR criterion of star target detected, star detecting probability is analyzed. Moreover the evaluation modal of the detection sensitivity in star system is deducted. The effects of detection sensitivity of APS star tracker were discussed.
The lowest sampling frequency not existing in theory
It was demonstrated that the lowest sampling frequency fmin_sample doesn't exist in mathematics. With mathematical analysis, the principles of sampling and reconstructing a continuous signal were strictly calculated. We found that the spectra of sampling data at critical sampling frequency fcritical_sample should overlap at the highest frequency fmax of the continuous signal. The fcritical_sample was defined as double of the fmax, viz. fcritical_sample=2fmax. As we know, the reconstructed signal will be distorted with this kind of overlapped spectra. Here, we will further illustrate the theoretical results. Aided with Fast Fourier Transform(FFT), the critical sampling and the process reconstructing continuous-time signal from it were discussed by spectroscopy. A symmetrical frequency-limited spectrum F(ω) was constructed with three modified rise-cosine pulses. Its corresponding time-domain signal f(t) was worked out theoretically. f(t) was sampled with δT(t). By modifying T, the critical sampling signal was obtained. With FFT, the spectrum Fd(ω)of the sampling signal was figured out. The calculated Fd(ω) was compared with the constructed F(ω), and was analyzed for observing frequency alias. A cycle of Fd(ω) for restoring the continuous signal could be obtained when Fd(ω) was filtered by an ideal low-passed filter. With FFT, a continuous signal was reconstructed from it. As the results, the spectra of sampling data at the fcritical_sampleoverlapped at the fmax. The reconstructed signal distorted obviously. So, the lowest sampling frequency fmin_sample doesn't exist. The sampling theorem couldn't include equal sign. It is unscientific to say that the f min_sample equal to double of the fmax.
The optical fiber detection network for methane concentration
Ji-long Zhang, Peng Wang, Xiao Li, et al.
Methane explosion accident is always the main threat to mine production. The two main physical factors of methane explosion are the concentrations of methane and oxygen comes to the explosive limits and the existence of fire source. It is very important to measure the concentration of methane in real-time and accurately for protecting the production safely. Among many methods of methane gas concentration measurement, harmonic detection is one of more effective methods for measuring the weak signal and raising the sensitivity of detection. The study based on the spectrum absorption properties of methane, adopted the Distributed Feedback LD, high performance gas absorption cell. The lock-in amplifier SR830 is adopted to measure the first and second harmonic signals for different methane concentration in this paper. And analyzed the data with LabVIEW. The analysis data validated the good linearity among the methane concentration and I2f/If (second harmonic/first harmonic) in the range from 0% to 5%, confirmed the superiority of second harmonic theory.
Passive laser spectrum detection technology based on static interferometer
Xiao Li, Ji-long Zhang, Er-ming Tian, et al.
Laser spectrum detection is an important technology which is used in laser reconnaissance and laser warning receiver. The identification of the laser spectrum can provide the information for optic-electronic countermeasure. On the basis of analysis of and research on the current laser spectrum detection technology, a passive laser spectrum detection system based on the theory of coherent spectrum detection and Fourier Transform spectrum detection technology was designed. The fiber optical antenna and modified wedge interferometer are system's important component parts, and the parameters of them are expatiated detailedly. The spectrum information was obtained after the Opto-Electronic transform by liner charge couple device (CCD) and Fourier transform by fast digital signal processor (DSP). The design method and the structure principle of key parts were analyzed detailedly in this paper, it also consisted the correlative performance analyze and setting up of experiment system. The result shows that the measure of wavelength of eight different semiconductor lasers, The test results indicate that the response time of the designed system is less than 10ms and the wavelength resolution is less than 10nm.
Reflected beam's direction deviation induced by the corner cube retroreflector
Jian Huang, Hao Xian, WenHan Jang
The direction deviation of the reflected beam induced by the corner cube retroreflector (CCR) is respectively discussed by geometrical optics approach and the principle of physical optics in this paper. A mathematical model was built to calculate the beam's aberration due to the fabrication errors of the CCR. It can be concluded that the centroid direction error of far field spot is much more appropriate to describe the reflection beam's direction deviation for a broad incident beam, and the beam with even intensity distribution should be used to reduce its direction deviation.
Measurement of corneal topography through Hartmann-Shack wave-front sensor
A corneal topography based on Hartmann-Shack Sensor is presented in this paper. In the system, the focus of an objective lens is precisely positioned on cornea's curve center. Wave-front of the reflecting beam can be measured by the Hartmann-Shack sensor which is conjugate to the cornea plane. If the corneal surface is a perfect sphere, wave-front detected by the Hartmann-Shack sensor is a plane. As a result, data measured by Hartmann-Shacks sensor is the deviation between the sphere and the real cornea surface. This paper describes a methodology for designing instrument based on Hartmann-Shack sensor. Then, applying this method, an instrument is developed for accurate measurement of corneal topography. In addition, measuring principle of Hartmann-Shack sensor which determined system parameters is also introduced. Repeatability is demonstrated by a series of data. The instrument was able to accurately measure simulative cornea's reflective aberrations, from which corneal topography and corneal refractive aberrations were derived.
A CMOS approach to coaxiality measurement of marine shafting and bearing system
This paper presents an approach to measuring the coaxiality of a shafting and bearing system for large and medium-sized ship using CMOS (Complementary Metal Oxide Semiconductor) image sensor. The measurement system consists of a laser diode with single mode fibre pigtail, which generates a reference datum-line, and position sensor of centre of shafting or bearings that is composed of a CMOS image sensor and a rotating inductance displacement transducer. The experimental results show that the approach meets the precision requirement of the coaxiality measurement. It provides flexibility and costs less. The method can also be applied to the positioning and accurate coaxiality measurement of similar bearing holes of large-scale axles.
The exploration of the characteristics of the hyperglycemia serum fluorescence spectrum
Now, spectra technology is widely used in the biomedicine research,so this study investigates variation of the fluorescence spectra in different excitation wavelength, and the spectra of serum with different glucose concentration is tested in the excitation wavelength of 240nm to 280nm. The experimental result shows that the correlation between the serum fluorescence intensity and the excitation light is very close, when the excitation light is in the ultraviolet wave band, the fluorescence of serum is intensive. There is a violent fluorescence emission wavelength, which is 300nm to 410nm, while the excitation wavelength ranges from 220nm to 290nm, and the peaks wavelength are 330nm and 370nm. From 240nm to 280nm, the serum fluorescence intensity increases synchronously with the glucose concentration, and the relationship between the fluorescence peak wavelength and the glucose concentration is almost in line. In this way the blood sugar concentration can be estimated by the fluorescence spectra peak wavelength when the excitation wavelength is from 240nm to 280nm, which is effective. It provides experimental foundation for the wide use of spectra technology in medical diagnose, and the effectiv method to test the blood sugar concentration.
3D registration method based on monocular vision and perspective model
The checkerboard target is precisely processed and fixed on the measurement system. The feature points' coordinates on the target in the measurement coordinate system are invariable with the motion of the measurement sensors, and obtained by using the intermediary coordinate transformation method. The feature points are captured by an accurately calibrated camera. The three collinear and equidistant points are used to build the simplest perspective-three-point model, and the coordinates can been calculated by the model. Not less than three non-collinear points, which can be obtained by two groups of models, are used to coarsely estimate the exterior parameters from the target coordinate system to the camera coordinate system. To improve the exterior parameters' precision, an optimization scheme is used to minimize the cost function of re-projection error. Every feature point' coordinates in the camera coordinate system can be accurately calculated. Finally, the registration matrix is obtained. Experimental results show that the new method is simple, flexible and effective.
Influence of the laser character on the resonance multiphoton ionization efficiency of NO molecule
Guiyin Zhang, Yidong Jin
The analytic formula of the ionization efficiency in the process of resonance enhanced multiphoton ionization is derived from the population rate equation. Based on this formula, the ionization efficiency of NO molecule, which is ionized via A2Σ, E2Σ intermediate resonant states and by (2+2) or (3+1) multiphoton process, versus laser intensity and pulse duration is analyzed by computer simulation. It is shown that the ionization efficiency of NO molecule increases with the laser intensity and pulse duration. When the photon flux is 2×1029photon•cm-2•s-1, all of the two steps in both processes are not get saturation as the pulse duration of the laser is 35ps. While the second excitation step is already saturated when the pulse duration is 6ns. And both of the two steps get saturation when the pulse duration is 50ns.Owing to the higher absorption transition cross section in the (2+2) process, the ionization efficiency via A2Σresonant state is with a much larger value than that of via E2Σstate. The ionization efficiency of NO molecule reaches saturation under lower laser intensity when it is ionized via A2Σresonant state. The optimum ionization pathway is decided when one detect NO by the technique of REMPI and with visible light as excitation source. It is the (2+2) multiphoton ionization process and via A2Σ intermediate resonant state. We wish the results can provide useful information for the detection of NO molecule.
Measurement of photoelectrons decay in doping AgCl by microwave absorption phase-sensitive technique
Xiuhong Dai, Guoyi Dong, Haiyan Liu, et al.
The generation and decay of photoelectrons is an important factor in improving photographic efficiency of silver halide crystals. Microwave absorption phase-sensitive detection technology designed by our experiment group, was used to non-contact measure the transmission characteristic of photoelectronic in [Fe(CN)6]4- uniformly-doped AgCl microcrystals. The signal of free and shallow-trapped photoelectrons were measured in-phase. It is found that the photoelectrons decay time in cubic AgCl microcrystals doped with [Fe(CN)6]4- is longer than that of undoped samples at the first exposure time. And the photoelectrons decay time becomes longer with the doping concentration increasing. As is shown the doping centres can act as shallow electron traps. The results also show the photoelectrons decay time decreases significantly till becoming a constant after a few minutes exposure, and the constant is lower when the doping concentration is higher. By analysis the photoproduct is silver clusters with the characteristic of deep electron traps in the microcrystals. The measurement of photoelectrons by microwave absorption phase-sensitive detection technology can give evidence for the improving performance of the photosensitive material, optical information storage material and so on.
Research on the electro-induced birefringence in bulk crystal silicon
Yu-Hong Zhang, Hang Liu, Zhan-Guo Chen, et al.
In this paper, the electro-induced birefringence based on Kerr effect and Franz-Keldysh effect in bulk silicon crystal at 1.3µm wavelengths has been measured, and the element of the third-order nonlinear susceptibility tensor, χ(3)xyxy, has been calculated. We find the change of refractive index induced by Franz-Keldysh effect is dependent on the polarization of the probing beam. Moreover, we deduce that the silicon crystal will become a single-axis crystal from an isotropy crystal when a silicon crystal is biased along [111] crystallographic direction, and the phenomena of birefringence willoccur as long as the light propagate perpendicularly to the optical axis of silicon crystal. In the experiment, we deduced the ifferences of refractive indices induced by Kerr effect and Franz-Keldysh effect were Δn = 5.49 x 10-16E2.50 and Δn/ = 2.42x10-16E2.50
The application of lidar in detecting space debris
Yang Wang, Qianqian Wang
The accumulation of space debris is expected to present an increasing threat to orbital aerostat. To develop and use space resource continually and in security the detecting technology for space debris has to be improved. The paper firstly introduces the concept of space debris and their common detection means, and then introduces the application of lidar in detecting the space debris. Comparing with conventional optical observation systems lidar adopts active detecting mode, without the limitation of illumination and with a long detecting distance. It also can measure range and speed of targets. Comparing with microwave radar the beam of lidar is narrow and it has great orientation precision and resolving power. To satisfy detecting small-sized debris in long distance and big area the paper proposes the composite method to detect the space debris which uses millimeter wave radar and optic equipment. It firstly uses millimeter wave with long distance and big view field to confirm the position of debris in long distance. And then it uses optical system with high resolving and anti-jamming power for accurate orientation and identification. It also measure the distance, angle and speed exactly of debris. The study in theory indicates this composite method can complete the detecting and orientation and achieve the distance, angle and speed of the space debris more than 10cm range beyond 150km.
Dual-frequency green laser interferometer based on a frequency stabilized 543.5nm Zeeman He-Ne laser
Jing Lei, Juqun Yan, Nanhai Song
A dual-frequency laser interferometer is established based on a frequency-stabilized 543.5nm Zeeman He-Ne laser. The interferometer has been tested in displacement measuring experiments in comparison with a commercial 632.8nm dualfrequency laser interferometer. Test results show that the achieved stability and the accuracy of the dual-frequency green laser interferometer have reached the level in commercial dual-frequency interferometers. Apart from being capable in heterodyne interferometry as a single-wavelength interferometer, the 543.5nm dual-frequency interferometer is also promising in two-wavelength interferometry when combined with the commercial 632.8nm dual-frequency interferometer, where both a high resolution and a relatively large range in displacement measurement can be achieved.
The influences of fog on the width of laser pulse transmitting in atmosphere
The characteristics of pulse laser transmitting in atmosphere were analyzed. An experiment setup was introduced to measure the impacts of fog produced by ultrasonic-nebulizer on time delay characters of the laser pulse transmission in atmosphere. The experimental results show that the width of laser pulse becomes wider while the laser pulse transmits in fog. The value of width broadened increases with the enhancement of fog thickness. The value of width broadened is substantially proportional to the extinction coefficient. The R-square of curve fitting is 0.9777. This relation may be used to estimate the atmosphere extinction.
Infrared testing for engine blades crack defects with laser scanning automatic heat loading
Fengming Bai V.D.M., Nuan Song, Lixiao Wang
In this paper, automatic scanning infrared laser nondestructive testing methods, such as aero-engine blades crack detection of defects; Use of thermal heating differential equations and leaves the surface temperature distribution in the infrared detection system to allow resolution under discussion laser scanning heating infrared detection engine blades crack defects. The method can be nondestructive testing of metal parts of the internal defects, such as micro-cracks, loose, porosity and so on, like the thin parts more effective. First introduced in the infrared detection system works as using laser scans of the work piece to be seized automatic heating pretreatment, to detect internal defects part of the nature and characteristics of purpose. The paper also build a two-dimensional analysis model of detected objects because of defective parts and non-defective parts of the geometry and physical properties of heat there is an obvious difference in surface temperature caused by the different response, therefore, can discuss affect of the temperature distribution of information, to determine the appropriate method. Discuss and analysis interaction between the loading heat flux density, length and depth of defects, and do some heat transfer analysis to measured the surface temperature distribution. Through load a constant heat flow to blades, the infrared detection system can obtain the surface temperature field of existence the temperature difference, which blades cracks determine the existence and its location.
Development of a near infrared spectroscopy analyzer for on-line process analysis
Huajun Ye, Lipeng Liu, Alin Xia, et al.
An on-line near infrared analytical system was developed for on-line process analysis applications. The system includes a near infrared spectroscopy analyzer and accessories (fibers, flow cell, diffuse reflection probes etc.). Its features and configuration were described in detail. Good performance was acquired: the wavelength range, resolution and stray light of spectra are 1000nm~2500nm, less than 5nm and less than 0.1%, respectively; the repeatability and uncertainty tolerances of wavelength are less than 0.02nm and 0.1nm, respectively; the temperature-induced drift of wavelength is less than 0.05nm/°C the slope and intercept ranges are 0.98~1.00 and -0.02~0.01 for photometric linearity, respectively; spectrophotometric noise is 1.3×10-5 (RMS) for high-light flux and 7.0×10-5 (RMS) for low-light flux. The above performance parameters of the analyzer meet and exceed the requirement of USP1119. Furthermore, the analyzer has been successfully applied to the laboratory, petrochemical factory and sugar mill. A Partial Least Squares (PLS) calibration model constructed from laboratory and factory samples was used for these applications. The application result reveals that the analyzer can meet all requirements. All results demonstrate that the analyzer has the merits of fast time response, excellent modeling, high accuracy and low maintenance cost and can deal with complex industrial environment.
Optical system transmittance detection base on the cross-correlation technique
The optical system transmittance is the ratio of optical instrument emergent light flux with incident light flux, and embodies the ability that transmitting light radiant energy of an optical instrument. It is an important performance index in optical system, especially in the telescopic optical system. In order to decrease the effect of the backlight, the traditional single channel detection method must be achieved in the darkroom. But it can not avoid the interference of 1/f noise and the illuminant wave because the detected signal is direct current signal, and the detecting accuracy is low. The paper proposes an optical transmittance detecting method with double beams and double frequencies based on the correlation detection technology. The method avoid the influences of 1/f, background light and illuminant wave effectively because of adopting the correlation detecting technology, and it not only can achieve the detecting in the bright field, but also improves the detecting accuracy finer than 1%, and could replace the single channel detection method that adopted at present.
Study on a novel laser target detection system based on software radio technique
Song Song, Jia-hao Deng, Xue-tian Wang, et al.
This paper presents that software radio technique is applied to laser target detection system with the pseudo-random code modulation. Based on the theory of software radio, the basic framework of the system, hardware platform, and the implementation of the software system are detailed. Also, the block diagram of the system, DSP circuit, block diagram of the pseudo-random code generator, and soft flow diagram of signal processing are designed. Experimental results have shown that the application of software radio technique provides a novel method to realize the modularization, miniaturization and intelligence of the laser target detection system, and the upgrade and improvement of the system will become simpler, more convenient, and cheaper.
3-D measuring of engine camshaft based on machine vision
Jianxin Qiu, Liang Tan, Xiaodong Xu
The non-touch 3D measuring based on machine vision is introduced into camshaft precise measuring. Currently, because CCD 3-dimensional measuring can't meet requirements for camshaft's measuring precision, it's necessary to improve its measuring precision. In this paper, we put forward a method to improve the measuring method. A Multi-Character Match method based on the Polygonal Non-regular model is advanced with the theory of Corner Extraction and Corner Matching .This method has solved the problem of the matching difficulty and a low precision. In the measuring process, the use of the Coded marked Point method and Self-Character Match method can bring on this problem. The 3D measuring experiment on camshaft, which based on the Multi-Character Match method of the Polygonal Non-regular model, proves that the normal average measuring precision is increased to a new level less than 0.04mm in the point-clouds photo merge. This measuring method can effectively increase the 3D measuring precision of the binocular CCD.
Focusing of hyperbolic-cosine-Gaussian beam with a spiral phase plate
Jinsong Li, Songlin Zhuang, Xiumin Gao
The focusing properties of the hyperbolic-cosine-Gaussian beam induced by spiral phase plates are investigated numerically. The phase plate may alter the wavefront phase of the hyperbolic-cosine-Gaussian beam by topological charge which results in spiral optical vortex. Results show that the topological charge of the spiral phase plate influences focal intensity distribution considerably, and some novel focal patterns, focal split appear in focal evolution with different topological charge. The focal evolution differs for different parameters in cosh parts of the hyperbolic-cosine-Gaussian beam. The optical gradient force is also illustrated to show promising application of the hyperbolic-cosine-Gaussian beam containing the spiral optical vortex in optical tweezers array.
Automatic testing device of multi-optical axis collimating
Yong Zhang, GuangBin Feng, Yong Li
With numerous hi-tech applications in photoelectric equipment, Single optical sensor has no capacity enough to shoulder those complex war-field tasks. Different photoelectric sensors have to cooperate effectively each other in order to exert effectively their own function. Therefore, how to test the multi-optical axis collimating aberration among each optical sensor is the fundamental precondition to guarantee the effective cooperation of each optical sensor. A new type automatic testing device is provided in the paper, which chooses the reflecting type parallel collimator as optical system. Design the paraboloidal lens as the primary mirror and the hyperboloidal lens as the secondary mirror not only guarantee the important index of resolving power but also shorten the length of collimator. Furthermore, design the laser spot collection set based on up-conversion effect of rare-earth material to satisfy the testing need between visible light axis and laser axis, which can capture effectively laser spot. Finally, design also a shift light set to meet the need of the practical distance between two axes of photoelectric equipment, which cover the shortage of the narrow caliber of parallel collimator. The merit of automatic testing device of multi-optical axis collimating aberration is prominent, such as excellent mobile capacity to meet the in-field condition, higher automatic degree to meet the different user and the broad applying field to meet different photoelectric equipment.
Spectral calibration method for all-reflected Fourier transform imaging spectrometer
Deqi Cui, Ningfang Liao, Ling Ma, et al.
All-Reflected Fourier Transform Imaging Spectrometer (ARFTIS) is a novel type of instrument based on Fourier transform spectroscopy. ARFTIS will offer high luminous flux and high spectral resolution, well suited to remote sensing with low energy. But there is nearly not any method of convenient spectrum calibration for this kind of instrument. In this paper, we analyze the spectrum calibration principle of ARFTIS and the cause of the calibration error. We reached the result that the calibration error is getting bigger with the increase of spectrum peak wavelength of the calibration light. By these we develop three convenient spectrum calibration methods used in Visible/Near-Infrared waveband, which are the Monochromatic Method, the Average Method and the Weighted Average Method respectively. We apply these methods to ARFTIS calibrate experiment. According to the experiment results, The Monochromatic Method can calibrate by using only one group of data, but with a little lower calibration precision. However the Weighted Average Method can provide a higher calibration precision than the other two methods. So, the Monochromatic method and the Weighted Average Method both have good application value for ARFTIS calibration.
Pulsed laser ranging techniques based on digital signal processing methods for automobile anti-collision application
Zhihui Sun, Jiahao Deng
A 1.55 µm digital laser radar system is designed and implemented for automobile anti-collision application. In order to reduce the influence of foggy, rainy and snowy weather on laser detection, digital signal processing methods are adopted. Multi-pulse coherent average algorithm is used to improve the signal-to-noise ratio of echo by N times. The correlation detection algorithm is adopted to estimate the time-of-flight. Multi-time delayed correlating method is used to improve the time-of-flight estimation resolution. Experimental results indicate that the digital signal processing methods in this paper can reduce the influence of bad weather conditions, and obtain high range accuracy.
Application of multi-sensors parallel fusion system in photoelectric tracing
Guo-ying Cheng, Sheng Cai, Hui-bin Gao, et al.
To solve the real-time and reliability problem of tracking servo-control system in optoelectronic theodolite, a multisensors parallel processing system was proposed. Misdistances of three different wavebands were imported into system, and then prediction was done in DSP1 to get the actual position information. Data fusion was accomplished in PPGA imported by multi channel buffer serial port. The compound position information was used to control the theodolite. The results were compared with external guide data in DSP2 to implement correction of above calculation, and then were imported to epistemic machine through PXI interface. The simulation experiment of each calculation unit showed that this system could solve the real-time problem of feature level data fusion. The simulation result showed that the system can satisfy the real-time requirement with 1.25ms in theodolite with three imaging systems, while sampling frequency of photoelectric encoder was 800 Hz.
Talbot effect under illumination of double femtosecond laser pulses
Wei Wang, Changhe Zhou, Enwen Dai, et al.
The Talbot effect under illumination of double femtosecond laser pulses has been reported. Spectrums of double femtosecond laser pulses with phase differences are quite different from that of one single femtosecond laser pulse. Therefore, the Talbot images of the double femtosecond laser pulses with phase differences are different from that of one single femtosecond laser pulse. Specifically, for the phase difference corresponding to π, the Talbot image shows the largest difference from that of one single pulse. Experimental results are in good agreement with the theoretical analysis. The behaviors of Talbot images under double femtosecond laser pulses illumination cannot be obtained under one femtosecond laser pulse, monochromatic or polychromatic light illumination. Therefore, it is a new interesting optical phenomenon for the Talbot effect which should have potential applications.
Evaluation of uncertainty in tunable diode laser absorption spectroscopy system used for continuous CO monitoring
Honglian Li, Xiaoting Li, Lianshui Zhang, et al.
Tunable diode laser absorption spectroscopy (TDLAS) is a method to detect trace-gas qualitatively or quantitatively based on the tunable characteristic of the diode laser to obtain the absorption spectroscopy in the characteristic absorption region. The concentration of CO is measured by tunable diode laser absorption spectroscopy (TDLAS) technology in this paper. The experimental results of measurement signals are inversely processed by applying the overall second harmonic least squares data processing algorithm. The experimental results indicate that the signal strength of the second harmonic spectrum changes with CO concentration. But the widths of the 2f lineshapes have not changed. The components that influence the uncertainty of measurement results during measuring CO concentration by TDLAS are analyzed and the mathematic model is built. The standard uncertainty of components and evaluation of uncertainty of measurement results are given with the direct evaluation method in detail. The evaluation results indicate that the major factors affecting measurement uncertainty are the indicating value uncertainty of the apparatus, concentration definite value uncertainty of calibrating gas.
Fiber Bragg grating AC current measurement based on fiber coupler demodulation
Yuan Yao, Benshun Yi, Xiaopeng Dong, et al.
The measurement of alternating current (AC) is realized by using fiber Bragg grating (FBG), giant magnetostriction material (GMM), and the technology of fiber coupler demodulation (fiber wavelength division multiplexing filter, FWDMF). The magnetostrictive effect of GMM, the theoretical analysis of the FBG current measurement and the interrogation technology of FWDMF are introduced as well. The sensing unit of AC current measurement is constructed with magnetostrictive material and FBG. The feasibility of AC current measurement by using this method is proved, when the AC exciting current is in the scope of 0~2A.
A subpixel algorithm using interpolation method based on normal direction
Li Gong, Zhong Wang, Chao Li
As one branch of subpixel technology, curve interpolation method is the most popular for its higher precision and less complexity. But the method has longer running time and bigger direction error, since it makes use of convolution between direction templates and pixel gray values to get Gradient direction which is interpolating direction. So a new method is proposed in which unisometric cubic spline interpolation is operated along the normal direction of the edge-point. It illustrates not only how to choose sampling points for interpolation, but also how to figure node values of those points, then establishes the suitable interpolating boundary conditions. The method reduces not only the uncertainty but also the runtime to 1/2, and improves measuring precision and efficiency.
Research on some issues of the method of photoelectric autocollimation for two-dimensional small angle measurement
Four issues of the method of photoelectric autocollimation for two-dimensional small angle measurement such as adjustment of calibration system, elimination of the effect on the measurement result induced by the installing position of the CCD camera relative to the autocollimator, processing methods of experimental data and repeatability of the system are studied in the paper. The calibration system which is composed of a precision motorized stage, a dual-frequency laser interferometer and a photoelectric autocollimator, is regulated to accomplish two separate calibrations around Z-axis and X-axis in the measuring coordinates system which is established by considering horizontal, vertical line of the crosshair and optical axis as X-axis, Z-axis and Y-axis respectively. Experimental results show that the formula method which can reduce the random error and remove the system error effectively with the average error of zero and the standard deviation 0.59". Compared with traditional optical autocollimator, the improvement of the photoelectric autocollimation method can be used to achieve rapid and automatic positional detection and error compensation of CNC rotary shaft.
Sub-pixel edge estimation based on matching template
Jin Zhang, Zhong Wang, Chun Yang, et al.
The significant disadvantage of traditional sub-pixel edge location algorithm is difficult to achieve high accurate edge location of micro-parts, because reflective characteristic of edge is widely divergent for material, chamfer, and any other factors. This paper introduces a sub-pixel location algorithm for micro-parts edge which is based on matching template. First, it studies the edge imaging characteristic for a specific practical engineering part, and constructs one dimension matching operator. Second, we abstract the pixel edge points on the image of practical engineering parts, and get the normal direction information of the whole points. Finally, according to the correlation operation between matching operator and a series of pixel points by the normal direction of the edge points, found the best position for matching. This position is the location point of the edge point under sub-pixel accuracy. Compared with traditional sub-pixel algorithm, this algorithm requires different matching operators for different measured objects, not a universal operator to all types of the edges. Therefore, the effect which brings by the parts' edge characteristic and the imaging characteristic can be reduced. This algorithm has prominence significance for using sub-pixel technology to measure practical parts. Experiment result shows that, for the practical engineering part which has clear measurement aim and conformable character of the edge, this method will achieve high accurate edge location, and it is suitable for wholesale measurement of edge for complex micro-parts which require high accurate.
The algorithm research of real time human tracking in video surveillance
Yuanfang Tan, Haiyang Liao
This paper presents the algorithm research of real time human tracking in video surveillance. This system consist of shadow detection, moving human identify and false object detection. We can identify the shadow from the foreground according to the changes of the illumination and the color changes when a point covered by a shadow gets darker. Through the step of the moving human identify, we use the codebook to classify the human from other objects. This algorithm is to find a code vector in codebook with the minimum distortion to the feature vector of object. If the minimum distortion is less than a threshold, this object is human. The based assumption of false object detection method is that object boundaries coincide with color boundaries. We find the false object which burst upon in the scene, and then use motion analysis to verify whether or not the tracked subject is indeed a human. The experiment result proved that the algorithms for real time moving human tracking are effective and robust.
Spatial phase-shifting lateral shearing interferometer
Xiaoxian Guo, Aijun Zeng, Huijie Huang
The phase-shifting lateral shearing interferometer is widely adopted for wavefront measurement with high accuracy. For real-time wavefront measurement, a spatial phase-shifting lateral shearing interferometer is proposed. The interferometer includes a polarization lateral shearing module, a spatial phase-shifting module and an imaging module. The polarization lateral shearing module consists of a Savart polariscope. The spatial phase-shifting module is component of a non-polarization beam splitter, a polarization beam splitter, two rectangular prisms and a half wave-plate. The imaging module includes an imaging system and a CCD. The measured wavefront is sheared by the polarization lateral shearing module. The polarization directions of the two shearing beams are perpendicular to each other. The two shearing beams are split into four groups of beams by the spatial phase-shifting module to form four interferograms in a 2x2 matrix. The phase step of the four interferograms is 90 degrees. The four interferograms are captured in a single frame image by the imaging module. In experiments, a spherical wavefront with large radius of curvature was measured. Four spatial phase-shifting interferograms of the wavefront was obtained simultaneously. The usefulness of the interferometer is verified.
Modeling and analysis of dialyte-lens auto-focusing technology for theodolite
Lin-tao Wu, Yan-feng Qiao, Deng-Ke Wu, et al.
In order to realize real-time auto-focusing for theodolite, lens-apart method was designed with the corresponding math model built and analyzed. An Object beam splitted after the first image surface of the theodolite traveled through two dialyte lens and then was imaged on CCD. The distance between two spots when exactly focused was set as the calibration value, and the relationship between defocus distance and spot offset was given. The influence of tracking center shift and divergence angle etc. on focusing accuracy was analyzed. Compared with the traditional focusing method, this scheme has a higher accuracy, faster calculation, higher tolerance for environment temperature and a simpler construction. The experiment result exhibited a resolution higher than 0.056mm, which shows a bright engineering application prospect for this method.
Calculation and simulation of the Jacobi matrix in electrical impedance tomography
Shujun Chen, Ge Kou, Aixia Jiang
Electrical impedance tomography is a kind of functional imaging technique making full use of human resistance carried by physiological and pathological information. However, the image reconstruction in EIT is a high ill-posed, non-linear, inverse problem, and it becomes a key and difficult point in EIT research. The calculation of Jacobi matrix in EIT is as the representive, for it requires several forward solutions to be computed. The paper focuses on the Jacobi matrix calculation method in order to reduce EIT computation based on disadvantages above. The Jacobi matrix is different when the electrode position and serial number are different in the finite element model. Jacobi formula is derived from the Newton-Raphson and the standard derivation method is adopted by comparing with the normal method, and it reduces the computation time effectively. Finally, the computer simulation and comparability of Jacobi matrix is given.
The simulation analysis of the scatterfield microscopy for the critical dimensions measurement
Lingfeng Chen, Dingguo Sha
Critical dimension measurement based on scatterometry is expected to be the key technology in current and future semiconductor manufacturing processes. Scatterometry has strong dependence on modeling. The paper compares the Integral Equation Solver and the Rigorous Coupled Waveguide Analysis (RCWA) technique from convergence, and chooses the RCWA method to simulate the critical dimension measurement. The paper introduces an angle resolved scatterometry technology constructed on microscope. The back focal plane of a bright field reflection microscope contains diffraction information about the sample, and positions in the back focal plane map to diffraction angles from the sample. With suitable control of the angle of the incident illumination, back focal plane imaging can provide information similar to that obtained from angle resolved scatterometry. The paper simulates the reflectance of the rectangular grating at a fixed wavelength (λ=532nm) versus angle of incidence, measured for both s polarization and p polarization. The silicon gratings are 10nm difference with line width, pitch, line height and sidewall angle. The simulations reveal that the p polarization light is more sensitive than the s polarization light to the changes of the grating size, and the scatterfield microscopy has nanometer level sensitivity to the line width variations.
An improved image matching technique for detecting piston
Dan-dan Qu, Yue-jin Zhao, Mei Hui, et al.
To achieve a good quality of image, piston of segment mirrors is required to be detected and removed down to a small part of λ. The details of the diffraction-interference pattern formed by the subaperture are sensitive to piston when observed on the image plane. An improved image matching method is introduced to detect piston according to the characters of the interference-diffraction patterns. Templates are made according to the parameters of the system. One-dimension projecting production-moment correlation method and projecting central moment eigenvector method are used in different conditions. The great advantage of this method is that there is no need of calibration so the measurement error is reduced. The operation is simplified to reduce the computation complexity by three matching steps. The measurement range is about um 25 ±um and the measurement error is less than 10nm. The experiment is carried out on a platform. Piston is introduced to the parallel-light by a piston generator which is controlled by a PZT. CCD with the pixel size 4.65um*4.65um is used to receive the image. The experiment result is basically consistent with the theory.
Ultra-weak luminescence is a sensitive method to evaluate cadmium resistance of maize varieties
In this paper, the delayed ultra-weak luminescence (UWL), Nitrate reductase activity and reactive oxygen species (ROS) contents of 3 different maize varieties (Zhengdan958, Jundan20 and Liaoyu18) under 50mg.L-1 CdCl2 stress were investigated. The results showed that the UWL intensity of all 3 maize varieties was decreased and the curve attenuating accelerated under the Cd stress. The total photon number reduced 12.8% (zhengdan958), 20.1% (jundan20) and 13.4% (liaoyu18), respectively. The activity of Nitrate reductase, which is a key marker reflecting internal physiology status, decrease 50.12% (zhengdan958), 58.80% (jundan20) and 55.80% (liaoyu18), respectively. The ROS contents increased remarkably under 50mg.L-1 Cdstress, ranging from 35.87% (liaoyu18), 40.90% (zhengdan958) to 42.23% (jundan20). From these results we speculated that UWL decreasing tendency was consisting with the change character of Nitrate reductase activity, and rather the in vivo metabolism reactions than the ROS contents, was the main resources of ultraweak photon emitting. Taken together, the UWL and the physiological status are closely related, ultra-weak luminescence could be used as a time-saving, sensitive method for evaluating cadmium stress resistance of different varieties of maize.
The application of information fusion in human eye aberration measurement
Peiming Zhang, Jiabi Chen, Liang Cao, et al.
A novel human eye aberration measurement method based on information fusion is presented here. We built a combined subjective and objective human eye aberration measurement system which is composed by an objective measurement part which measure human eye aberration by using Hartmann-Shack wavefront sensor and a subjective view test part through which can test the subject's vision. The deformable mirror can compensate the high order aberrations of human eye, and thus, can improve the visual acuity of human eye. We had weighting process on Zernike coefficients of both psychology stimulated results and objective results by the method of information fusion, and got combined Zernike coefficients, and finally the combined wavefront aberrations. The result shows that information fusion can combine advantages of both subjective and objective measurement, can have more comprehensive to characterized human eye visual performance, thus providing a more detailed advice for ideal individual human eye.
Study of photoacoustic imaging based on all-optical detection
Photoacoustic imaging is attracting increasing interests in biomedical imaging. The comparing between the traditional piezoelectric detections and optical detections is described. Three kinds of all-optical detection photoacoustic imaging systems, including system based on optical reflectance at a glass-liquid interface, system based on FP polymer film and the system based on POISe, are introduced and compared in this paper. Because these methods are difficult to realize measuring the photoacoustic signal on a 2D plane with the backward detection mode, a new kind of photoacoustic imaging system based on Electronic Speckle Pattern Interferometry (ESPI) is proposed. An ESPI outside displacement measurement system is adopted to detect the surface displacement of sample. Since the exposure time of a standard CCD which is of the order of tens of milliseconds, the temporal resolution to sample an acoustic field at MHz frequencies is achieved by interrogating the sensor with a short laser pulse whose bandwidth is about 20ns. After measuring and disposing the displacement data of the sample at a series detecting time, the photoacoustic image will be reconstructed by a delay and sum beam-forming algorithm or by a reconstruction algorithm based on the decomposition. In principle, the system will realize noncontact and backward-mode inspection and smaller element sizes of the receiver in the photoacoustic imaging application.
Two-dimensional minimum discontinuity phase unwrapping based on tabu search
Yuangang Lu, Ting Zhang, Xuping Zhang
Phase unwrapping is the task of recovering the true phase values, given the wrapped phase values in an image. Flynn's minimum discontinuity phase unwrapping algorithm can deal with many different kinds of phase unwrapping problems successfully. However, since it takes the whole wrapped phase image as the improving loop search areas, Flynn's algorithm has low efficiency in searching for the phase's discontinuity. To overcome this drawback, a new minimum discontinuity phase unwrapping algorithm based on tabu search is proposed in this paper. In the proposed algorithm, the nodes of the wrapped image are divided into different N levels according to the corresponding quality of the wrapped image and the nodes with high levels are added into tabu list. In the iteration process of improving loops search, the tabu list is updated according to the aspiration criterion to allow the search areas extend to nodes with high levels. By this means, it searches the highest probability nodes belonging to paths of improving loops first and the lowest probability nodes last. As a result, it significantly improves the efficiency of the algorithm. The proposed algorithm is described in detail and verified by use of an experimental wrapped phase image with noise and undersampling. Unwrapped results show that the proposed algorithm works well and is more effectively than the Flynn's minimum discontinuity algorithm.
Radiation acquisition and RBF neural network analysis on BOF end-point control
There are some problems in Basic Oxygen Furnace (BOF) steelmaking end-point control technology at present. A new BOF end-point control model was designed, which was based on the character of carbon oxygen reaction in Basic Oxygen Furnace steelmaking process. The image capture and transformation system was established by Video for Windows (VFW) library function, which is a video software development package promoted by Microsoft Corporation. In this paper, the Radial Basic Function (RBF) neural network model was established by using the real-time acquisition information. The input parameters can acquire easily online and the output parameter is the end-point time, which can compare with the actual value conveniently. The experience results show that the predication result is ideal and the experiment results show the model can work well in the steelmaking adverse environment.
A novel edge detection approach used for online dimensional measurement of heavy forging
Chunhai Hu, Xiaoxue Song
An edge detection method was developed with capability of objectively detecting significant edges in images of high temperature forging. The issue of potential image degradation when viewing hot objects was serious concerned. The paper was absorbed in online dimensional measurement using stereovision technology. Particular characteristics of high temperature forging were described. A global self-adaptive thresholding preprocessing was used for eliminating most redundant mill scale regions and segmenting object from complex background. Then, the feature edges was detected and localized at single pixel scale. Post processing of surround suppression as final additional step was applied to improve edges detection performance by extracting genuine feature edges from edges map. The entire method was performed on a real hot forging image and the performance had been proved in experiment result. The approach was specifically designed for using in online dimensional measurement of heavy forging, but generally enough to be applied to other edge detection of any high-temperature object.
Resolution improvement of the electronic theodolite in automatic guided laser theodolite system by subdivided locating method of image
Electronic theodolites are widely used for spatial coordinate measurement in assembly manufacturing industry, but the traditional operation of theodolites is time-consuming, which can not meet the application of online measurement. So in the automatic guided laser theodolite system including two electronic motored theodolites, a method for improving resolution of the electronic theodolite based on subdivided locating of laser spot image was expounded to eliminate the errors. On the basis of a brief introduction of the automatic guided laser theodolite system, factors related to the measuring errors were analyzed, with the conclusion that angle resolution of theodolite had an effect impact on the phenomenon of no coincidence between the laser spot and the target point. Then the image including the message of the laser spot adopted by the external camera was processed to subdivide in pixel level. Sequently comparison of the measuring results was made between the original measuring data and the data corrected by the subdivided locating method in the same theodolite measuring model to evaluate the feasibility of the operation and to find the most suitable interpolation method. The experimental data of the system verified the high precision and efficiency of the method.
A high precision metrology method and system for thin film's parameters based on reflectance spectrum
Zhiyong Dai, Zengshou Peng, Zhonghua Ou, et al.
How to determine the parameters of thin film precisely and rapidly becomes more and more important. In this paper, a new method based on reflectance spectrum combining complex-shape method to determine multi parameters of thin film simultaneously by dwindling the polyhedron is first presented. On the one hand, this new method fix out the problem of multiple solutions well. On the other hand, for there is no dependence on interferential spectrum and transparent area, the method can be applied to diverse sorts of reflectance spectrum with a fast speed, nice convergence, and high precision. In the meantime, the metrology system based on this method is built up and measured experiment for standard thin film sample is implemented also. Comparing the measured results to the standard values of the standard thin film sample, the results show that the error degree is about ± 3%. The experimental results prove this method has a nice application value.
Volumetric calibration of multi-axis machine tools through parametric way
Abdul Wahid Khan, Wuyi Chen
A methodology was implemented to evolve the volumetric errors of multiaxis machine tools through a parametric way. The volumetric error was calibrated and evaluated in the workspace arbitrarily by implementing parametric methods and techniques. In parametric method linear displacement errors and angular displacement errors were measured through a laser interferometer with combination of a newly developed three-line measuring method to measure the prismatic joints for efficient and quick error meterage. Besides these, squareness errors between the axes were also quantified by using reversal method. Volumetric accuracy portrayed the real error picture between the workpiece and cutting tool or end effectors or a measuring probe. So positional errors, straightness errors, angular errors and squareness errors were quantified and transformed into volumetric accuracy by using generalized homogenous transformation matrices, whereas forward kinematics technique was used as a tool. Measured results can be used to compensate the volumetric errors to achieve high precision in manufacturing and measurement through physical compensation, making correction, adjustment or improvement through software. Reported here is the volumetric accuracy results carried on a multi-axis CNC milling machine under controlled environmental conditions and as per the standard procedure and practice.
Online self-calibration technique for trace gas analyzer based on tunable diode laser absorption spectroscopy
Yong Zhu, Jun Zhang, Junqing Chen, et al.
To compensate the measurement error induced by temperature and pressure variation in a tunable diode laser absorption spectroscopy (TDLAS) system, an online self-calibration technique is introduced. More specifically, a reference gas cell filled with known proportion target gas is placed on site, surrounded by working gas to be measured. Thereby, the temperature and pressure inside the reference cell are equal to the gas outside. The TDLAS system acquires the absorption spectrum of the reference gas cell and the working gas synchronously. And the concentration of the trace gas in working gas can be easily obtained by calculating the absorption intensity proportion of both absorption spectrums without considering the affection of temperature and pressure. The principle, design, and experiment of this technique are presented in this paper.
A study of sub-pixel interpolation algorithm in digital speckle correlation method
Yong Lv, Qibo Feng, Liangyu Qi
Sub-pixel interpolation technique is a way that getting sub-pixel gray value by interpolation algorithm and then it is substituted into the correlation expression to calculate the sub-pixel position. It is a key way to improve the displacement measurement accuracy in Digital Speckle Correlation Method (DSCM), meanwhile, it is more time consuming than other steps. A new quarter sub-pixel registration method is proposed which can significantly cut down the sub-pixel searching time. On the premise of not reducing accuracy, an improved Taylor's series expansion in gradient algorithm is used to get higher registration speed. At the same time, a new cubic convolution interpolation method is proposed to get extremely high accuracy. These conclusions are proved by the results of the experimental system.
Precise scintillation correction for an Earth-to-space optical communication link
Shengbo Hu, Xin Meng
Optical telecommunications will be the next technological step in Earth-to-space communication. However, propagation of an optical beam through the irregular atmosphere results in significant distortion of the signal, necessitating correction schemes for Earth-to-space communications. Conventional approaches to correct distortions that are based on natural or artificial guide stars are useful in astronomical imaging, but have practical difficulties or are not adequate to correct the distortions important for Earth-to-space optical links. Then we proposed a system, which employs an orbiting spacecraft with a bright laser reference source and a relay mirror, can provide essentially perfect scintillation correction.
Triangular linetype wavelength calibration process for micro-spectrometers with multichannel detectors
Yuzhao Wang, Yinchao Zhang, Yan Wu, et al.
An advanced wavelength calibration process with higher wavelength accuracy is developed based on the conventional calibration method of micro-spectrometers with multichannel detectors. In the conventional method, the unit of pixel data for calibration is pixel. A pixel unit usually has a length measured in μm, and the wavelength peak is not always in the middle of a pixel. Thus, the location of a spectral line's peak can't be got accurately. The length of a pixel arouses a measurement error of wavelength-peak location. And the error of wavelength-peak location results in error of pixel wavelength calibration. A new method, applying triangular linetype to approach the real spectral linetype, which enhance the wavelength-peak location accuracy, is introduced in this article. The method is proved useful in theory and a function for calculating the accurate pixel location is produced from the method. Two steps are added to the conventional method before the final pixel-wavelength fitting. First, three-pixel data collection is carried out. In the conventional method, only the highest pixel of one spectral line is chosen for calibration, but that is not enough for getting more accurate wavelength peak location. In the new method, three pixels, including the highest one and its two neighbors, are collected for the more accurate wavelength-peak location process. Second, sub-pixel calculation is executed to enhance the peak location accuracy. On the assumption that a triangular linetype can approximately replace the real linetype in theory, the wavelength-peak location is calculated more accurately and the precision of the result is better than 0.5 pixel. When an unknown spectral line is measured, accurate wavelength-peak location can be got in the same way. The experiment was based on a compact spectrometer HR4000, with a crossed Czerny-Turner optical design, produced by Ocean Optics Company. Its manufacturer's calibration precision, which is given by the company, is 0.24nm. Mercury lamp's line spectra are used as wavelength standards. The results show that by applying the new method, the wavelength-peak location accuracy improves from 1 pixel to around 0.5 pixel, and the wavelength accuracy improves from above 0.2nm to around 0.1nm.
PSO based Gabor wavelet feature extraction and tracking method
Hongguang Sun, Qian Bu, Huijie Zhang
The paper is the study of 2D Gabor wavelet and its application in grey image target recognition and tracking. The new optimization algorithms and technologies in the system realization are studied and discussed in theory and practice. Optimization of Gabor wavelet's parameters of translation, orientation, and scale is used to make it approximates a local image contour region. The method of Sobel edge detection is used to get the initial position and orientation value of optimization in order to improve the convergence speed. In the wavelet characteristic space, we adopt PSO (particle swarm optimization) algorithm to identify points on the security border of the system, it can ensure reliable convergence of the target, which can improve convergence speed; the time of feature extraction is shorter. By test in low contrast image, the feasibility and effectiveness of the algorithm are demonstrated by VC++ simulation platform in experiments. Adopting improve Gabor wavelet method in target tracking and making up its frame of tracking, which realize moving target tracking used algorithm, and realize steady target tracking in circumrotate affine distortion.
Focusing and leveling system for optical lithography using linear CCD
Tao Huang, Shiyuan Liu, Pengxing Yi, et al.
This paper proposes a focusing and leveling technique for optical lithography tools using linear CCD and image processing method. A double telecentric optical system is designed, which projects an aperture onto the surface of the wafer at a large incident angle, and then the reflected beam results in a spot image onto a linear CCD. A mathematical model relating the spot lateral displacement to the change of wafer height is established. Two image processing algorithms for displacement detection of the spot image measured by the linear CCD are also proposed. A lot of experiments including the system calibration conducted on a test rig confirm that the proposed technique is feasible and effective. The repetitive height measurement accuracy of the system is verified to be more than 200 nm within a wide band measurement range of 1 mm.
Numerical simulation of auto-adapted deflection tomography
A new deflection tomography algorithm was suggested and tested with a simulated flow field. The programs calculating deflection projection and inverse projection were worked out based on optical refraction principle and mathematical, physical significance of tomography. With our home-made Simple Self-correlative Algebraic Reconstruction Technique (SSART), a new deflection tomography algorithm was programmed and named auto-adapted deflection tomography system. A section of a complex flow field was simulated with Gauss and rectangle window functions. One positive and one negative Gauss peaks were constructed on the section in order to make the model contain double-polar components. One square tower was constructed on the section in order to make the model contain much more high-frequency waves. The deflection projections were figured out according to the tomography algorithm with direction interval one degree. So, we got 180 direction projections in total. 12 projections were selected out by direction step 15 degree, and 84 projections were picked out by direction interval 2 or 3 degree. The section was reconstructed with the projections by SSART. The reconstructed results were compared with the model. The reconstructive effect was estimated with Mean-square error(MSE) and Peak error(PE). As the result, the system could reconstruct the simulated field accurately. With twelve projections, MSE was about from 0.0001 to 0.0006 at the end of 300 cycle iterations, and PE was about from 0.007 to 0.020. With selected 84 projections, the MSE was 0.00000999, and PE was 0.00013142. So, the auto-adapted deflection tomography system can accurately reconstruct complex flow fields.
Transformation and analysis of pixels based on low-level-light image
Youtang Gao, Yuan Xu, Si Tian, et al.
Brightness transformation of low-level-light images, which only depends on the characteristics of every pixel, can change the brightness of pixels. In this paper we firstly analyze the low-level-light images, proposing two ways to transform the brightness of pixels: brightness correction and gray-scale transformation. And during the brightness correction is changing the brightness of pixels, it is necessary to consider something such as the brightness it used to have and its position in the image. While gray-scale transformation doesn't need to consider its position in the image during it's modifying the brightness of pixels.
Z-scan determination of third-order nonlinear optical properties of Poly(4,4'-diazobenzene-2,5-thiophene)
Huawei Shao, Mei Xiang, Zhenhong Jia, et al.
A novel material,Poly(4,4'-diazobenzene-2,5-thiophene) (PDABTh) was synthesized and its third-order optical nonlinearity was studied using Z-scan technique with 20 ps laser pulse at 1064 nm. We measured the nonlinear refractive index n2=8.4x10-19 m2/w with positive sign and nonlinear absorption coefficient β=1.8x10-12 m/w with reverse saturable absorption. The molecular second-order hyperpolarizability was calculated to be 4.2x10-30 esu. The special Π-electron structure may contribute to these relatively large non-linear optical properties. This suggests that the PDABTh may have a potential application in nonlinear optical devices.
Moire fringe measurement in the data and pixel match of holographic disc storage
In digital holographic disc storage, in order to achieve accurate data quickly read and write, and reduce the bit error rate, it is necessary to make pixel 1:1 match between spatial light modulator (SLM) and charge coupled device (CCD). However, how to make the Fourier lens precision assembly and achieve pixel match is a difficult problem. In this paper, based on the Moire fringe of precision measurement technology, a method was to put forward because some Moire fringe appearance can indicate the location error of machine parts and magnification of lens, on the point of angle and cycle analysis of Moire fringe, this problem can be solve. Experiment showed that use of this method the pixel 1:1 match between SLM and CCD achieved. The raw bit error rate of SLM reached 1.5x10-4 and 2.5x10-4 for mask.
Vision detecting of arc welding pool surface topography based on projected grating
Yanfeng Wang, Nansheng Liu, Youzhi Yuan
A vision detecting of arc welding pool surface topography system was setup in this paper. A semiconductor laser as an active light-source which is projected laser on to the specialized grating and frost glass by collimating lens, deformed grating fringes are formed on the surface of arc welding pool, narrow band filter and neutral density filter are mounted on CCD for detecting pool surface topography at real time on the other side of the system. When projecting angle and shooting angle are selected properly, it can be avoided the interference of arc for pool image better, deformed grating fringes of pool surface can be detected. Deformed grating fringes are reflected the information of concave or convex of the pool. Two categories of stainless steel are experimented, deformed grating fringes of pool are got clearly under the condition of different welding current and different welding speed, pool edge is extracted by digital image processing technology, the geometric parameters of pool Front-side is obtained by demarcated and calculated successfully.
Optoelectronic technology application for measuring nonlinear optical properties by different geometry degenerate four wave mixing
Wei-Bo Wang, De-Ying Chen, Rong-Wei Fan
Nonlinear optical properties of optical materials are important factors. Degenerate four-wave mixing (DFWM), as a detective tool for yielding effectivex (3) values, is imposed the condition of phase matching on the incident and generated signal beams. Nowadays DFWM with forward geometry (FDFWM) has found increasing usage. However, phase-match is automatically achieved in the back phase-conjugated geometry but in the forward folded boxcars geometry. Also, the efficiency of DFWM reaches its maximum value when all three input beams are of the same intensity with regardless of the absorption coefficient and the detuning conditions. Further, weak signal beams under the strong background of stray light are hardly positioned and distinguished. To solve the problems, a new optoelectronic technique for detecting forward DFWM spectroscopy on iodine vapor has been performed. With the help of the detecting system, phase matching can be easily achieved in the optical arrangement. Finally Real-time detecting the rate of signal to noise so as to timely decrease the stray light with correct methods. This system makes it feasible that the potential application of FG-DFWM is used as a diagnostic tool in combustion research and environment monitoring.
Effect of pupil filter position on superresolution properties of confocal measurement system
Lirong Qiu, Weiqian Zhao, Junjie Guo, et al.
Confocal measurement system is recently widely used as important tools for measurement of three-dimensional microstructures and surface contours because of its good 3D chromatographic imaging capability. And superresolution pupil filter is often used for improving the resolution of confocal measurement system because of its easy structure, thereby satisfying the measurement requirement of ultra-precision microstructures for higher spatial resolution. Because the pupil filter improves the resolution by changing the amplitude and phase distribution of light beam, the position of pupil filter has an important effect on the resolution. In this paper, the measurement model of confocal measurement system is established for different position of pupil filter, and based on these models; the resolution properties are analyzed by emulation to confirm the best position of pupil filter in the measurement system. And the optimized phase-only filter is combined with a confocal measurement system to improve the lateral resolution and the test setup is established. In order to verify the validation of the above theory, the standard step is measured using the established setup when the pupil filter is at different position. Preliminary experiments and analyses indicate the system using a phase-only filter at different positions can achieve different resolutions.
Thermographic method for evaluation of thermal influence of exterior surface colour of buildings
Yanpeng Wu, Deying Li, Rendong Jin, et al.
Architecture colour is an important part in urban designing. It directly affects the expressing and the thermal effect of exterior surface of buildings. It has proved that four factors affect the sign visibility, graphics, colour, lighting condition and age of the observers, and colour is the main aspect. The best method is to prevent the exterior space heating up in the first place, by reflecting heat away room the exterior surface.The colour of paint to coat building's exterior wall can have a huge impact on energy efficiency. While the suitable colour is essential to increasing the energy efficiency of paint colour during the warm summer months, those products also help paint colour efficiency and reduce heat loss from buildings during winter months making the interior more comfortable all year long. The article is based on analyzing the importance of architecture color design and existing urban colour design. The effect of external surface colour on the thermal behaviour of a building has been studied experimentally by Infrared Thermographic method in University of Science and technology Beijing insummer.The experimental results showed that different colour has quietly different thermal effect on the exterior surface of buildings. The thermal effect of carmine and fawn has nearly the same values. The main factor which is color express, give some suggest ting about urban color design. The investigation reveals that the use of suitable surface colour can dramatically reduce maximum the temperatures of the exterior wall. Keywords: architectural colour, thermal, thermographic
Design and realization of FEC-based RS code in the atmospheric laser communication system
Limin Chang, Lu Song, Lijing Zhang
The RS(Reed-Solomon) code is an important linear block and used for solving the problem of serious distortion and BER(Bit Error Rate) in the atmospheric laser communication system. RS (255,223) code are selected as channel code. Meanwhile, technologies for the laser communication system such as encode, interleaving, decode have been discussed in details. In this paper, an improved RiBM algorithm is adopted in the key equations solver of decoding algorithm. In the Forney's algorithm, inversion circuit in finite field is adopted. Then, division operation in the error value is realization by subtraction of power exponent. As a result, the whole decoding chip obtains the optimization in the speed and the usage resources. The hardware structure design and algorithms program have been finished on FPGA according to CCSDS specification. The BER performance verification has been applied in Visual C language. The experiment results show that coded data can obtain SNR (Signal-to-Noise Ratio) gain of 3-5dB when BER requirement of 10-5 is satisfied in this system.
Research on fault diagnosis technique on aerocamera communication based on fault tree analysis
Lijuan Li, Binggao He, Chengjun Tian, et al.
ARINC429 is the standard of digital transmission of avionic device. This paper used fault tree analysis to diagnosis failures of aerocamera 429 communication, built up fault tree of aerocamera 429 communication, analyzed and diagnosed the failures, and designed the detecting flaw, finished aerocamera 429 communication detecting system finally. This detecting system can detect aerocamera 429 communication board fast and effectively, and cut down period of clearing of fault. In addition, it can increase the direction of maintenance and repair, improve the overall function of aerocamera.
The micro-strain measurement research of a double-microscopic of digital speckle correlation measurement
Kun Ma, Jiaquan Wu, Xiaoyu Chen, et al.
Digital speckle correlation method (DSCM) has been widely used in experimental mechanics to obtain the surface deformation fields. But one of the challenges in practical applications is how to obtain the high accuracy with micros-strain at the measurement precision of με. A double-microscopic of digital speckle correlation measurement is described in this paper. The design concept for the optical system, for which double microscope and double CCD is combined to measure micro-displacement in our experiment. The experiment shown the proposed correlation theory and measurement system method is sufficient satisfies the security engineering measurement needing.
The deep electronic trap effect of cyanine dye on the surface structure of AgCl microcrystal
In this paper, the influences of cyanine dye on the photoelectron decay of silver chloride micro-crystal have been studied with Microwave absorption and dielectric spectrum detection technology. The free photoelectron decay of silver halide sensitized becomes faster than that of pure silver halide, and the FDT are 86ns and 109ns for silver chloride sensitized(5.0ml/40g AgCl emulsion) and unsensitized, respectively. The absorption peak of the dye is at about 550nm, having about 50 nm red shift compared with that in methanol. This indicates that J- aggregate is formed on micro-crystal surface, moreover the peak of dye J-aggregate becomes sharper, the width of absorption peak narrower with the increasing of the concentration of dye. Dye J-aggregate increases the concentration of deep electronic trap in the surface of silver halide micro-crystals.