2005 Vol. 26, No. 5

Testing Technology
Research on Automatical Measuring System for Spatial Light Intensity
WANG Xiao-peng, WU Bao-ning, YUAN Liang, YU Bing, YANG Feng
2005, 26(5): 1-003.
After investigations on the methods usually used in measuring the spatial light intensity of lamps, a new test method for spatial light intensity is proposed. A data model, which can automatically align the spatial light intensity of a lamp, has been established. The structure and principle of the system for automatically measuring the spatial light intensity are introduced. The threedimensional figures of spatial light intensity were drawn with a 2D scanning system and a dedicated test softwave (Matlab). With the technology we can rapidly derive the lightintensity distribution in x and y axes, and the divergence angle of the lamp. An example of measuring a projection lamp is given in details. The ideal results, among which the peak light intensity is 2634.4 cd and the divergence angle is 15.25°, are acquired in the experiment while a lamp is 5m away from the detector of the system.
Optical Axes Boresight Instrument for Multispectral Optical System
ZHAN Qi-hai, CHANG Ben-kang, FU Rong-guo
2005, 26(5): 4-006.
A test equipment for boresighting the three optical axes of the groundbased observing and aiming system that consists of laser, day light, IR(or low level light) sensors is introduced. Its test principle and process to measure the optical axes boresight of the three sensors mentioned above are described in details. During the design of the line graticule, we did not use the ruling technique on glass, but selected Wwire to make the LOS and welded two electrodes at the two ends respectively. This design can avoid any possible error caused by the replacement of the crossline graticule observation when a multispectral optical system is tested. This equipment provides a foundation for precision adjustment by detecting and testing of the optical axis boresight in the multispectral optical systems, accordingly making the optical axis bore sight of the three optical sensors fulfill the boresight accuracy requirement of the system instrument and ensuring the direction consistence of observation aiming and rangefinding.
An Improved Measurement Technique for Atmospheric Attenuation of Laser Transmittance
Xu Dai-sheng, Hu Yi-hua, hu Rong, Wang Jian-yu
2005, 26(5): 7-009.
It is understood that the characteristics of the atmospheric attenuation materials (haze, smoke, dust or aerosol) are important factors for applications such as military conflict, environmental protection and prevention of forest fire. However, the current atmospheric attenuation measurement method for laser transmittance could not achieve accurate results because it does not take the fluctuation of the laser pulse energy into account. In order to overcome such problem, a new test scheme and data processing method is designed. To take the laser energy fluctuation into consideration, a beam splitter and a laser receiver are added to the traditional design for monitoring the change of laser energy. Therefore, the emitting energy of the laser pulse is monitored and it can be used for inverse data processing for far field reception energy. Finally, the measurement accuracy of the transmittance is significantly improved and reliable data are provided to decision makers.
Study on Fluorescence Spectrometer for Monitoring Pesticide Residues in Vegetables
WANG Yu-tian, WANG Zhong-dong
2005, 26(5): 10-012.
A fluorescence spectrometer which can measure pesticide concentration is designed by using a xenon lamp as excitation lightsource,employing optical fibers to transmit and detect fluorescence and combining with CCD spectrumdetermination technology based on fluorescent characteristics of carbaryl that can emit fluorescence as it is excited by UV rays.Moreover,the rapid measurement of carbaryl residues in cucumbers is implemented with a steadystate fluorescent spectrograph and the new system respectively. The results indicate that the linear concentration range is 0.0~120.0μg/L for carbaryl, the detection limit (LOD) is 5×10-7μg/L,the linear correlation coefficient r is 0.9991 as the excitation wavelength is 319nm and the fluorescence emission wavelength is 647nm. The data prove up to the hilt that the instrument meets the demand of fluorescence detection.
Theoretical Study
Point Spread Function in Coded Aperture Imaging System
CHENG Li-hong, TIAN Xiao-dong, XIE Cun
2005, 26(5): 13-016.
In the study of X ray coded aperture imaging system, it's known that the point spread function(PSF) decides the performance of a imaging system. MTF can be deduced by PSF and the filter used in image reconstruction can be made thereby, so the accuracy of PSF directly affects the performance of reconstructed image. In this paper, based on the scalar theory, PSF is obtained theoretically under the condition of considering diffraction effects. The filter of the optical system is fabricated based on PSF. The filtering processing for the frequency distribution of coded overlapping image was done with Wiener filtering function and then the reconstructed image was obtained through the inverse Fourier transformation.
Study of Fraunhofer Diffraction From Complementary Sierpinski Carpet Grating
TIAN Li, DAI Dong-yun, LIU Sheng-hua
2005, 26(5): 17-020.
The Fraunhofer diffraction phenomenon on the complementary structure of Sierpinski carpet grating is discussed on the basis of FresnelKirchhoff theory and Fourier analytical method. The frequency spectrum,amplitude and lightintensity functions are derived. The diffraction phenomenon of grating is simulated by use of the MATLAB software, and the curves of its frequency response characteristic are plotted. The result shows that in diffraction patterns of allorder gratings, the higher amplitude part is concentrated in the center area of the receiving screen and the lower amplitude in the area around the center, but in the further area far away from center it tends to 0. In the whole, the diffraction patterns manifest the obvious fractal characteristics as well as the basic features of the diffraction.
Infrared Technology
Research of the SiTF Measurement for Thermal Imaging Systems
LI Xu-dong, HU Tie-li, YUE Wen-long, FU Jian-ming, XUE zhan-li, YAN Xiao yu, WANG Xuexin
2005, 26(5): 21-024.
The signal transfer function(SiTF) is considered as the most basic and important parameter to evaluate the characteristics of the infrared thermal imaging system,and is the linear portion of the responsivity function. The information on gain, Linearity, dynamic range and saturability of UUT can be obtained from the test curves of the responsivity function. The Optic Metrology Station is currently engaged in a research on the evaluation of the synthetic characteristic of the infrared thermal imaging system.In this paper,the CEDIT IIA thermal imaging system is measured with the diblackbody and reflected target system. The equipment can ensure the uniformity and stability for the backgraound radiation,and also ensure it against the effect of the ambient temperature,so the accuracy and reliability of measurement are improved. Finally, according to the practical experience many years,the author lists the causes for variations in the measurement of SiTF.
Detection Based on MultiDegree andOrientation Gradient Fusion for Weak Infrared DotObjects
ZONG Si-guang, WANG Jiang-an
2005, 26(5): 25-028.
Experiments indicate that the traditional methods of infrared image detection are not ideal because of the bigger noise of infrared image. The algorithm based on multidegree andorientation gradient fusion is presented to recognize the dotobiects in the lowcontrast infrared image polluted by heavy noise and stray waves. Experiments for detecting dim dottargets with the above method are carried out. The result indicates that the detection performance of the multidegree andorientation gradient fusion is better than that of the adaptive filter and medium filter. The algorithm is especially suited to the surveillance systems of low frame rate and can detect the dottargets with signal to clutter ratio equal to 1.
Metrology Technology
Research on Temperature Characteristics of Absolute Calorimetric Energy Meter for HighEnergy Laser
WANG Lei, YANG Zhao-jin, Li Gao-ping, LIANG Yan-xi
2005, 26(5): 29-032.
The temperature differential characteristics of inner and outer faces of absorbing cavity used in absolute calorimeter laser energy meter is studied theoretically and verified experimentally. Firstly, with the thermal conduction equations of second homogeneous boundary and nonhomogeneous boundary condition,we gained the temperature distribution in and after the heating process of the absorbing cavity. Secondly, through the simulation for the process of laser heating of the absorbing face, we obtained the expermental data of the temperature difference.In the end, with numerical simulation method, the theoretic results are analyzed numerically. The experimental data is very close to the theoretic analysis result, which proved that though fixed temperature difference is existed during laser heating, it will be soon reduced and the absorbing cavity will reach the heat balance after laser heating is finished.
Fiber Optics
Multi-channel Serial Optical-fiber Data Transmission System
WANG Heng-yun, CAO Zhan-min, ZHANG Xing-she
2005, 26(5): 33-036.
This paper introduces a medium and long-range optical-fiber(cable) communication system which can be used in data tranmission of point-to-point or between two local-area-networks. Using optical-fiber as a transmission media, the system is immune from electromagnetic and nuclear radiation interference,and can be applied to some special environments or places unaccessible by human. While the microcontroller is used in the transmitter and receiver in this system,it makes a feature of simple structure, high reliability, the powerful data processing function and flexible design for baud rate of serial port, and fits in with the need of different transmission rate of serial port. It meets the requirement of the remote-control-and-monitor for medium,longrange signal transmission in civil and military fields. Therefore,it has a great potential in the fature.
WANG Jin-e, LIN Zhe-hui, WU Yu-lie, LI Shengyi
2005, 26(5): 37-040.
The autoalignment technique is studied for the PM fiber (PMF) of matching refractiveindex(MRI). The polarization observation by lenseffecttracing technique(POL) is introduced. Based on the POL,an autoalignment system is designed and its performance is then tested. Different lightintensity distribution characteristic is found on the different observation surfaces in a series of experients. The widest range of adjustment is achieved when the observation surface corresponds to a lightintensity distribution with five characteristic points. This means it is easier to focus.The fivepoint method is presented after analysis of the curves of the five characteristic points with respect to the azimuth angle of the optical fiber.By comparison with the POL,this method is easier to be realized and has higher measurement accuracy,so it is suitable for autoalignment system.
Refractive Index Profile Measurement of Singlemode and Multimode Fiber
HAO Ai-hua, MAO Zhi-li, HE Feng-tao
2005, 26(5): 41-044.
Through analyzing some measurement procedures of refractiveindex profile of singlemode and multimode fibers; their essential differences are obtained. Since the core of singlemode fiber is very small, its propagation mechanism can be analyzed only by the wave theory,and the measurements with the farfield and nearfield methods are all based on the scalar Helmholtz wave equation, that is the refractiveindex profile measurements for singlemode fiber are according to its basic transmission theory. Whereas the core of multimode fiber is larger, the ray theory is appropriate to analysis of its propagation principle. The reason is that the multimode fiber refractedray method and nearfield scanning method are all based on the numerical apertures of various radii and the corresponding refractive patterns and propagation patterns.
Thin Film
A Study on Photosensitivity Characteristics of Ba1-xSrxNbyTi1-yO3 Thin Film on SiO2/Si Substrate
SONG Qing, HUANG Mei-qian, LI Guan-qi
2005, 26(5): 45-049.
Ba1-xSrxNbyTi1-yO3 thin film (45nm) deposited on a SiO2/Si substrate by the argon ionbeam sputtering technique is employed to fabricate planar thinfilms resistors used in the IC standard technology.The absorption spectra of the Ba1-xSrxNbyTi1-yO3 thin films, the photocurrent under different illumination and voltage, and the photocurrentfrequency characteristics of the filmresistors are studied.The experimental results show that Sr and Nb doped in BaTiO3 produce the impurity energy level in forbidden gap. Therefore,the energy gap drops down to 2.7eV and there are some consecutive absorption peaks in the visible region. The film has good photobehavior in the range from near ultraviolet to visible light, and it has high photosensitivity, high photoconductive gain and high linear illumination performance. While the illumination intensity is weak, the variaion of the current will be large, which is called onecenter recombination process; while the illuminaion is strong, the variation will be smooth and more linear, which is called twocenter recombination process.In this paper, the frequency response of the Ba1-xSrxNbyTi1-yO3 thinfilm resistor is investigated. The lifetime of optically excited carriers is 27ms at 200Lux.
The Optimizing and Designing Method of Multilayer Film
WANG Hong-chang, WANG Zhan-shan
2005, 26(5): 50-053.
Since the global optimization seeking method used in the traditional multilayer design is very slow and difficult to get an ideal film system, an optimizing method based on the wellknown Frensnel equations and simplex optimization is used in the design of optical element of multilayer for soft Xray and Xray. The highest theoretical reflectivity of a soft Xray periodical multilayer at different wavelengthes is calculated, and the results are same as those calculated by the random search method, but the computing velocity of the simplex optimization is much faster than the random search method. The simplex method is also used in the optimizing design of the Xray supermirror, and the ideal result is obtained.
Analysis of Thermal Convection and Conduction in the Dome of LAMOST
LI Rong, SHI Hu-li, CHEN Zhi-ping
2005, 26(5): 54-060.
A software of thermal analysis,Icepak,is used to calculate the heat exchange in enclosing channels of LAMOST.The effect of the thermal radiation and conduction of the enclosed wall surface on the whole temperature field is emphatically analyzed.Based on the cooling scheme of ventilating duct, the models of the thermal radiation and conduction are set up respectively, and the heattransfer structure on the walls in the dome is described with them. The temperature filed distribution of the main optical assembly (focal surface) is calculated with a simulation method when the thermal radiation and conduction on the wall surface are increased, and the calcution results are compared and analyzed.The numerical calculation and simulation results show that the effect of the wall surface heat transfer on its internal temperature field is not serious, the cooling shcheme of ventilating duct can control the maximal temperature gradient on the focal surface within 0.4℃/m successfully and the characteristic structure of enclosed wall is effective on the heat transfer. The conventional cooling project is still powerful with the new structure of the walls. The thermal analysis and simulation are helpful to the theoretical study on the seeing and the design of the LAMOST dome.
Development and Applications of Optical Glasses
WANG Yao-xiang
2005, 26(5): 61-066.
With the development of photonic technique,the novel optical function glasses which could change the polarization, frequency, coherency and monochromaticity of light, produce and detect photon, become a main development subject in optical glass field. In this paper the sgnificant development of optical glasses and their applications in the fields of optics and information technology are introduced. The development trend and the characteristics of the main optical functional glasses such as nonlinear opticl glass, gradient index glass, laser glass and other optical function glass are pointed out. Finally the progress made by chinese optical glass industry has been reviewed.