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Performance test of steel tube enclosed thermistors in air temperature measurements (EI CONFERENCE) 会议论文
3rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2011, January 6, 2011 - January 7, 2011, Shanghai, China
Chen H.; Peng J.; Yan F.; Sui Y.; Yang H.
收藏  |  浏览/下载：23/0  |  提交时间：2013/03/25
The performances of two steel tube enclosed precision thermistors are tested in a well controlled air environment to determine if the thermistors have enough accuracy for 0.01C levels of air temperature gradient measurement. Three Fluke's 5641 and three 5610 thermistors were tested for 24 hours in Fluke's 7008 calibration bath in the first step. In the second step  the performances of these two thermistors in steady state and transient state air temperature environments were tested for 8 hours separately. The results illustrate that  two of the 5641s were airproofed in a temperature well controlled tube  when steel tube enclosed precision thermistors are used in air temperature measurement  there are unstable departures from each other with a maximum 8.8 mC in constant air medium and 27 mC in temperature changing air medium. The transient-time errors are too large to show the true amounts of temperature changes for air temperature measurement. 2011 IEEE.  
Analysis of atmospheric pressure and temperature changes on the image quality of aerial camera (EI CONFERENCE) 会议论文
2011 International Conference on Mechatronic Science, Electric Engineering and Computer, MEC 2011, August 19, 2011 - August 22, 2011, Jilin, China
Dong B.; Tian H.-Y.
收藏  |  浏览/下载：22/0  |  提交时间：2013/03/25
This paper starts from the study of the aerial camera's work environment  analyzes the temperature and atmosphere pressure changes on aerial camera's imaging quality of influence. Point out that when the altitude of the camera changes  atmospheric pressure and temperature of constant change  so the camera's optical focal surface position changes  thus affecting the image quality of the camera  causing changes in the camera's focal surface optical  and affecting the camera's image quality. Summarize the rules that the temperature and pressure influence the image quality of the camera in aerial environment. Analyze the various environmental conditions on the impact of camera's image quality. For different types of camera  put forward the corresponding convergence compensation method  and provides a reference value to the development of the aerial camera. 2011 IEEE.  
Research on the laboratory radiometric calibration of the thermal imager (EI CONFERENCE) 会议论文
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, April 26, 2010 - April 29, 2010, Dalian, China
Lu Z.; Sun Q.; Wang J.; Lu Z.; Liu Y.
收藏  |  浏览/下载：17/0  |  提交时间：2013/03/25
The radiometric calibration of the thermal imager was investigated to build the relationship between the input radiance and the digital output to realize the temperature measurement. The radiometric calibration was implemented in the State Key Laboratory of Applied Optics. A standard black body source was served as radiation source. The response of the thermal imager to the input radiance was tested for different gains. The experimental results show that the average grey level of the output imaging is linear dependence of the input radiance. Because the radiance in the receiving wave range of the thermal imager is linear with the black body's temperature based on Planck's law of radiation  the average grey level of the output image is also linear with the black body's temperature after fitting a curve to the experiment data points. Then the relationship of the response and the gain was studied when the black body's temperature kept constant. The preliminary analysis of calibration data shows that the response of the thermal imager is linear and the average grey value of the image is directly proportion to the gain. According to the experimental results  the reference gains and the dynamic range of temperature measurement were obtained. Finally  the uncertainty influencing the calibration results was analyzed  the analysis shows the maximal uncertainty is 5.2%  which can meet the calibration requirement less than 10%. 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.
收藏  |  浏览/下载：21/0  |  提交时间：2013/03/25
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.  
High power vertical cavity surface-emitting laser with high reliability (EI CONFERENCE) 会议论文
Optoelectronic Materials and Devices II, November 2, 2007 - November 5, 2007, Wuhan, China
Changling Y.; Guoguang L.; Chunfeng H.; Li Q.
收藏  |  浏览/下载：12/0  |  提交时间：2013/03/25
Temperature-enhanced ultraviolet emission in ZnO thin film (EI CONFERENCE) 会议论文
Zhang Y. J.; Xu C. S.; Liu Y. C.; Liu Y. X.; Wang G. R.; Fan X. W.
收藏  |  浏览/下载：15/0  |  提交时间：2013/03/25
We have studied the structural and optical properties of ZnO thin films prepared by thermal oxidation of ZnS films deposited by plasma assisted electron-beam evaporation on Si(1 0 0) substrates. The transformation from zinc blende ZnS to hexagonal wurtzite ZnO is confirmed by Raman and X-ray diffraction (XRD) measurement. For the sample thermally oxidized at 600 C for 2 h  a novel UV emission peak Ix located at 3.22 eV (385 nm) has been observed. The temperature-dependent photoluminescence spectra show that the integrated intensity of Ix increases exponentially with increasing temperatures within the measuring temperature range  from 80 to 300 K  but the peak position remains nearly constant. We explain this behavior in terms of electron tunneling into the radiative recombination centers.  
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.
收藏  |  浏览/下载：18/0  |  提交时间：2013/03/25
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.  
Phase characteristics of laser beam in fibers (EI CONFERENCE) 会议论文
5th International Workshop on Adaptive Optics for Industry and Medicine, August 29, 2005 - September 1, 2005, Beijing, China
Chai C.; Liu S.; Liu J.; Wang L.; Jia G.
收藏  |  浏览/下载：19/0  |  提交时间：2013/03/25
The phase changing rates1 of laser beam in single mode polarization maintaining fiber (PMF)  Yb-doped rectangular inner cladding dual-clad fiber (DCF) and Yb-doped large-mode-area dual-clad fiber (LMF) are investigated by means of interference under situations with different exterior disturbance  for situations that all the fibers are used as transmission medium only  as well as amplifying medium with the last two. In this paper  phase fluctuation characteristics of the beam transmitted through the fibers with no amplification are presented. The results show that the phase fluctuation frequencies of the laser beam transmitted through these three kinds of fibers are mainly in the range of 100-200Hz  100-300Hz and 80-400Hz respectively in normal laboratory environment. The phase fluctuation frequencies of the laser beam transmitted through the DCF  in cases of when the environment temperature is changing  a constant pressure is applied to the fiber and when vibration is applied  are mainly in the range of 100-600Hz  100Hz-300Hz and 100-500Hz respectively. In the same cases  for the LMF  the phase fluctuation frequencies are mainly in the range of 150-600Hz  100-400Hz and 100-1000Hz  respectively. It indicates that for realizing phase stabilization  the bandwidth of any potential phase control2 system has to be in the range of a few kilohertz.  
All-solid-stated laser controller design based on digital optical feedback (EI CONFERENCE) 会议论文
Lasers in Material Processing and Manufacturing II, November 10, 2004 - November 12, 2004, Beijing, China
Liu L.; Wang J.-L.; Zhou C.-Y.; Ge W.-Q.
收藏  |  浏览/下载：23/0  |  提交时间：2013/03/25
The new design about a CW  digital all-solid-stated LD pumped Nd:YVO 4 controller is introduced. The stable output power of this digital laser controller which adopts Digital Signal Processor(TMS320C31) is approximately 20mW. The whole system is composed of constant- current source  protection circuit  pulse-width modulation circuit  Si-photo-detector and amplified circuit and Digital Signal Processor control system  etc. In terms of error deviation Based on nonlinear control curves of LD power output by Si-photo-detector  the region control can be obtained by means of the PID control algorithm in the software platform  that is  error amendment and high stability laser power output can be achieved. And the precision of temperature control can reduce from 0.2C to 0.04C. By adopted integral separated mode PID control algorithm  the LD output power instability ( %) down to 2%. By way of adopting the new digital design  the work to protect the laser diode  including the continuous adjustable output power with high accuracy and stability  is easily obtained. The internal-external modulation control of the laser power based on digital optical feedback can be accomplished with stable power output. At last  the bringing reasons of noise are analyzed and the solving methods are put forward in this paper.  

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