Abstract:The surface passivation of Mercury Cadmium Telluride (MCT) materials is one of the crucial steps for fabricating photoconductive and photovoltaic detectors. Practical MCT devices need stable and reproducible passivated surfaces and the surface potentials which meet their performance requirements. The research progress of the surface passivation of MCT materials is presented. The basic concepts of the passivation of MCT materials are described. The growth methods, interface properties and parameters of some passivation layers are discussed.

Abstract:A shipborne infrared alert detection system combined with a shipborne search radar can be used to fully warn the coming sea-skimming missiles and low-flying aircrafts. How to evaluate the ability of the shipborne infrared warning system to capture antiship missiles is an important subject to be solved in the field of air defense of ships. By analyzing the shipborne infrared warning system, a method for evaluating the effectiveness of shipborne infrared warning systems is proposed. The method provides an important basis for the effectiveness evaluation of naval air defense antimissile systems.

Abstract:The advantages and disadvantages of four kinds of methods such as modulation transfer function method, point spread function method, pixel processing method and ray tracing method are analyzed and compared. According to the features of infrared imaging sensors, a simulation idea of combining the modulation transfer function method with the ray tracing method and the processing method based on image pixels is given.

Abstract:A multi-mode silica fiber coupled InGaAs detector was designed. The performance of the chip was measured before and after its coupling. The factors which had influences on its coupling efficiency were analyzed. The result showed that the silica was suitable to be coupled with the InGaAs chip. In the waveband from 0.9 μm to 1.7 μm, the maximum coupling efficiency could be greater than 30 % when an optical fiber with a diameter of 100 μm was used. When an optical fiber with a diameter of 500 μm was used, the maximum coupling efficiency could be greater than 55 %. The light intensity exhibited Gaussian distribution at the exit end of the multi-mode silica optical fiber. With the increase of the distance between the end face of the fiber and the chip surface, the half-width value of the Gaussian distribution curve was increased and the light beam gradually diverged. The transverse offset and longitudinal discrepancy between the chip and the fiber end had a great influence on the coupling efficiency, and the transverse offset was a more significant influence factor.

Abstract:In infrared detection, the quantitative analysis is usually based on the relationship between the specified characteristic time and the defect depth. Using a stainless steel plate with six flat-bottom holes as an experimental sample, the defect depth is calculated by using a PSDT method which need not to choose any reference. When the time of the second-order derivative of logarithmic temperature peak is taken as the characteristic time, the defect depth is measured according to the proportion of the characteristic time to the square of defect depth. The data calculation for any point can be implemented with a VC program. Firstly, the data is fitted by using the least square polynomial. Then, the second-order derivative peak time of the logarithmic temperature-logarithmic time is calculated. The result is displayed precisely in figures and the defect depth is automatically measured finally.

Abstract:When a single spherical mirror is used to compress laser beams, there usually is a problem that the poor divergence can be resulted in or too many spherical lenses have to be used. By using a ABCD matrix method to analyze the Gauss beam passing through a single lens in theory, a conclusion that the beam from a semiconductor laser can not be collimated ideally with a single lens is drew. A design scheme based on ZEMAX is proposed for the collimation of a semiconductor laser source. The design and optimization method is given. For a 808 nm semiconductor laser commonly used in engineering, a collimator with two lenses is designed and its aberration is corrected by using the proper optimization function and weight in ZEMAX. By using a non-spherical surface, fine collimation is implemented at a divergence angle of 0.032 mrad. This design has the features of less lenses and simple structure.

Abstract:Evapotranspiration is an important component of the water budget of wetland. By using the remote sensing technology, the evapotranspiration of wetland can be computed effectively and appropriately. The remote sensing classification technology is combined with the quantitative remote sensing technology. In view of different land with different evapotranspiration sources and different water and heat transfer mechanisms, an integrated model is established and is used to analyze and compute the evapotranspiration of some major wetland. By comparing the average evapotranspiration of different wetland with the measured data, it is shown that the integrated quantitative remote sensing model of wetland evapotranspiration combined with classification can get a good result.

Abstract:Two different application modes of flexible gyroscopes, i.e. open loop and close loop, are presented. The stability of a system in both application modes is analyzed in terms of torque rigidity. In theory, the torque rigidity of a system is limited by the bandwidth of the gyroscope when it operates in the close loop mode. In the open loop mode, the torque rigidity of the system is not limited by the bandwidth of the gyroscope and can be increased greatly. The simulation and test result shows that the open loop mode is more effective than the close loop mode for a gyroscope. It can improve the torque rigidity and stability of the system. This result validates the correctness of the theoretical analysis.

Abstract:A new method which combines Partial Least Squares (PLS) with a near infrared spectroscopy is proposed for the nondestructive discrimination of the varieties of sugar. A near infrared spectrometer is used to obtain the diffusion spectral characteristic curves from the samples of white granulated sugar, xylitol, maltose and glucose. Then, the PLS is used to derive the variety and characteristic values of the sugar. The derived eleven main components which are normalized are used as the parameters for establishing a fuzzy clustering model. By setting four clusters, the fuzzy clustering model is established and is used to predict forty unknown sugar samples. The prediction accuracy is up to 100 %. This shows that the new method has a good ability to fast discriminate the variety of sugar.

Abstract:The near infrared spectroscopy and chemometrics were employed to discriminate Xihu longjing tea and Zhejiang longjing tea. First of all, the raw spectra were pretreated with standard normal variant SNV function. And then the SNV-pretreated spectra were used as the X variant of PLS-DA; principal component analysis were conducted on the SNV-pretreated spectra, and the first ten scores of principal component were used as the input of least square support vector machine (LSSVM) and radial basis function neural network (RBFNN). The parameters of the relative weight of the regression error (γ) and the kernel parameter of the RBF kernel (δ₂) were optimized with grid research and leave-one-out cross-validation technologies, and the optimized γ and δ₂ were 229.1 and 124.9 respectively. Meanwhile the best numbers of neuron in hidden layer of RBFNN was 27. With comparison the performance of three models, LSSVM showed the best performance. The RMSECV and R₂ were 0 and 1 in calibration set respectively, while RMSEP and R₂ were also 0 and 1 in validation set respectively. As a result, 100% of Zhejiang longjing tea and Xihua longjing tea were classified.