中国开放科研知识云: 检索

Comparison of radiation temperature measurement precision between middlewave and longwave thermal-imaging systems (EI CONFERENCE) 会议论文
2012 International Conference on Optoelectronics and Microelectronics, ICOM 2012, August 23, 2012 - August 25, 2012, Changchun, China
Sun Z.; Zhu W.

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A comparison study on temperature measurement precision between middlewave 3-5m and longwave 8-12m measuring thermal imaging systems has been conducted. The study was limited to systems working in indoor conditions and the target's temperature is in the range of 270K900K. First the Disturb Resisting Function (DRF) of infrared systems is deduced. On the base of DRF curve we find that the middlewave infrared system get the smaller influences under the same size disturb compared with the longwave system. A theory of the influence of target's physical characteristic and measurement conditions on the accuracy of temperature measurements has been developed. On the basis of the developed formulas an analysis of the influence of signal disturbances (because of incorrectly assumed emissivity limited transmittance of the atmosphere radiation reflected by the object and shift of optics radiation) on the accuracy of temperature measurement has been made. It has been found that the middlewave systems in typical temperature range offer generally better accuracy in temperature measurement than the longwave ones do. 2012 IEEE.

Research on defect detection technology of C/C composite (EI CONFERENCE) 会议论文
2011 International Conference on Advanced Engineering Materials and Technology, AEMT 2011, July 29, 2011 - July 31, 2011, Sanya, China
Zhao W.; Dong J.; Li W.; Wang H.; Guo Q.

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Carbon matrix/Carbon fibre reinforced composite(C/C composite) has many special characteristics such as high strength high elastic modulus high temperature resistance and ablation resistance. So it is used to manufacture rocket engine nozzle in aerospace filed. But its security will be seriously effected during rocket engine working due to the manufacturing defects. Based on analyzing defect types and structure characteristic of C/C composite the ultrasonic and infrared testing methods on C/C composite are further studied in this thesis. and effective defect detection has been achieved. (2011) Trans Tech Publications.

Ground-based measurement of the space object temperature (EI CONFERENCE) 会议论文
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes, April 26, 2010 - April 29, 2010, Dalian, China
Wang G.-Q.; Wu Y.-H.; Wang J.-L.; Zhao J.-Y.

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Multi-band IR data of the space object can be used in the fields of object identification and space surveillance. The radiation characteristics of the object can be obtained by analyzing these data. These characteristics include temperature area emissivity absorptivity reflectivity and temporal trends. The infrared radiation temperature of the space object is an important characteristic from which the object's working state in orbit can be judged. We apply the method of measuring the spectral distribution of the object and fit the data to the Planck formula to determine the temperature. In order to improve the precision of measuring temperature on the space object we optimize the centric wavelength and the bandwidth effectively. Also we use a simple program to implement temperature measurement. 2010 Copyright SPIE - The International Society for Optical Engineering.

Method for obtaining real temperature of space object by using the ratio of emissivity at different wavelengths (EI CONFERENCE) 会议论文
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, November 19, 2008 - November 21, 2008, Chengdu, China
Guo-Qiang W.; Tao C.; Jian-Li W.

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The infrared radiation character (temperature and efficiency radiation area) of a space object is an important characteristic we can judge the state of the object working in orbit by measuring temperature and variety. Due to lower temperature of the object and far distance between the object and the earth the infrared radiation signal is faintness therefore temperature and the infrared radiation character is difficult to measure. There are several methods to measure the temperature of the object in theory and each one has its applicability respectively such as applying Wien Law to compute temperature based on Stefan-Bolzmann law to compute temperature and utilizing multi-spectrum detector to measure temperature As a whole these methods are based on the hypothesis that the object is a Black-body or the radiance emissivity is constant. In fact homochromatic radiance of object is not a constant but a function that changes with wavelength. Since the problem that an object whose homochromatic radiance s not a constant which results in temperature can not be computed accurately we bring forward a method to contrast the luminance of the object at different wavelengths and deduce the relationship among homochromatic radiance and wavelength and the temperature of Black-body from which we can compute real temperature of object. 2009 SPIE.

The calibration of faint simulation star magnitude based on single photon count technique (EI CONFERENCE) 会议论文
International Symposium on Photoelectronic Detection and Imaging 2009: Advances in Imaging Detectors and Applications, June 17, 2009 - June 19, 2009, Beijing, China
Gan X.-J.; Guo J.; Xu S.-Y.

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A calibration method of faint star magnitude of the star scene simulation device is proposed in this paper. In the research of simulation star magnitude luminometers and CCD devices are the general calibration devices which are used to measure the illumination intensity and calibrate its magnitude. But if the simulation magnitude is only sixth magnitude its illumination intensity is only 1.010-8 Lux. This illumination intensity level is the lowest illumination intensity that the commercial luminometer can detect. Hence the simulation star magnitude lower than six magnitude cannot be calibrated by luminoters. Likewise CCD devices also need an additive cooler in this case. When the single photon characteristic is presented due to the low luminosity of simulating light sources the simulation star magnitude can be calibrated by detecting its photon flux of radiation with the method of single photon count. In this paper the detection principle of single photon based on a compact designed PMT detecting of the radiation level of simulation star magnitude is advanced. Especially a spectrum match method is proved theoretically to be an effective means for selecting PMT photosensitive type. In the case of the detection object of the simulation star in visible wavelength a analysis indicates that the material of tri-alkali cathode materials its best choice after being compared the Signal-to-Noise of photon detector of several PMT photosensitive materials based on the different spectrum match ratio of different object light sources and different cathode materials. An experiment is employed to show the relationship of control voltage of PMT and its dark counter the relationship of the environment temperature of PMT and its dark counter which proves its only decades of CPS at room temperature. The so low dark counter avoids a bulky cooler and is convenient for installing it on the star scene simulation equipment. Finally in the experiment of calibrating the simulation star magnitudes the ability of its calibration is confirmed to reaches up to 12m meanwhile its calibration error is within 0.2m. 2009 SPIE.

Temperature characteristics of high power vertical cavity surface emitting lasers (EI CONFERENCE) 会议论文
Semiconductor Lasers and Applications III, November 12, 2007 - November 13, 2007, Beijing, China
Yan C.; He C.; Lu G.; Qin L.

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By using oxidation confinement technology high power vertical-cavity surface-emitting lasers are fabricated in experiment. The electrical and optical performance characteristics such as threshold current efficiency emission wavelength and output power are measured under continuous wave (CW) condition at room temperature. The maximum output power is up to watt regime at wavelength of about 980nm. The temperature characteristics of the device are investigated experimentally in detail. The variation in lasing threshold current with temperature is studied. The characteristic temperature T0 of the device is derived and the value is about 211K. Such a high characteristic temperature T0 of threshold current can lead to good temperature sensitivity of the device. At the same time the lasing spectrum characteristics with temperature are also measured. The wavelength shift with temperature is just about 0.06nm/K. From the measured results it is shown that the device can still operate at high temperature condition.

Vertical-external-cavity surface-emitting lasers: Numerical simulation, and characterization (EI CONFERENCE) 会议论文
Optoelectronic Materials and Devices III, October 27, 2008 - October 30, 2008, Hangzhou, China
Yan C.; He C.; Lu G.; Qin L.

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Firstly the vertical external-cavity surface-emiting lasers (VECSELs) device structure and model was given and the output characteristic was simple calculated. Then in experiment the VECSELs were grown bonded on to the heat sink and optically pumped by high-power 808nm diode laser array with fiber output module the light emission spectra were measured. Finally The thermal characteristic of the VECSELs was investigated by changing the temperature of the substrate. 2008 SPIE.

Temperature characteristics of several familiar diode lasers with broad area (EI CONFERENCE) 会议论文
Optoelectronic Materials and Devices III, October 27, 2008 - October 30, 2008, Hangzhou, China
Liang X.; Qin L.; He C.; Ma Q.; Ning Y.; Wang L.

收藏 | 浏览/下载：17/0 | 提交时间：2013/03/25

Temperature characteristics of several familiar high power diode lasers with broad area whose wavelength was separately 808 nm 810 nm 940 nm and 980 nm were analyzed. In order to see the effect the change of the quantum well structure on the characteristic temperatures different structures were attempted. For the 808 nm structure we tried different barrier thicknesses. For the 810 nm structure different cavity lengths were attempted. And we studied the 940 nm and 980 nm also. In this paper the widths of these devices were all 100 m. Characteristic temperatures of these devices were calculated. The appropriate structure was available for different application. 2008 SPIE.

Application of high-precision fuzzy control alorithm with self-regulation factor in RF hyperthermia system (EI CONFERENCE) 会议论文
6th International Conference on Machine Learning and Cybernetics, ICMLC 2007, August 19, 2007 - August 22, 2007, Hong Kong, China
Wang B.-D.; Chen Y.-Y.; Jiang C.-H.

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RF hyperthermia system is a kind of medical device to restrain and kill cancer tumor base on RF heating technique and biology heating effect theory. The mathematical model of the control system is very difficult to be formed due to the extreme complication physical process of temperature increase during the thermal treatment and the various structure and characteristic of internal tissues. In this paper we present a new fuzzy control algorithm in which a self-regulation factor is adopted to realize real-time temperature control with high-precision controller. By means of software arithmetic and hardware adjustment accurate temperature and time control can be achieved in this system. 2007 IEEE.

Intelligent MRTD testing for thermal imaging system using ANN (EI CONFERENCE) 会议论文
ICO20: Remote Sensing and Infrared Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China
Sun J.; Ma D.

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The Minimum Resolvable Temperature Difference (MRTD) is the most widely accepted figure for describing the performance of a thermal imaging system. Many models have been proposed to predict it. The MRTD testing is a psychophysical task for which biases are unavoidable. It requires laboratory conditions such as normal air condition and a constant temperature. It also needs expensive measuring equipments and takes a considerable period of time. Especially when measuring imagers of the same type the test is time consuming. So an automated and intelligent measurement method should be discussed. This paper adopts the concept of automated MRTD testing using boundary contour system and fuzzy ARTMAP but uses different methods. It describes an Automated MRTD Testing procedure basing on Back-Propagation Network. Firstly we use frame grabber to capture the 4-bar target image data. Then according to image gray scale we segment the image to get 4-bar place and extract feature vector representing the image characteristic and human detection ability. These feature sets along with known target visibility are used to train the ANN (Artificial Neural Networks). Actually it is a nonlinear classification (of input dimensions) of the image series using ANN. Our task is to justify if image is resolvable or uncertainty. Then the trained ANN will emulate observer performance in determining MRTD. This method can reduce the uncertainties between observers and long time dependent factors by standardization. This paper will introduce the feature extraction algorithm demonstrate the feasibility of the whole process and give the accuracy of MRTD measurement.

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