Abstract:A three-layer thermal vegetation canopy model applicable to forest canopies was developed and tested by field experiments. The model is based on the energy budget equations that describe the interactions between short and long wave radiation, sensible heat flux and latent heat flux within three horizontally infinite canopy layers. Particularly it concerns the wind, air temperature and water vapor pressure profiles in the canopy, which were never considered in the earlier models. In solving the nonlinear energy budget equa- tions, a new method was adopted, resulting in the reduction of the model computer time greatly. The calculated results of the model are in good coincidence with the observed data, which shows that the new model is able to simulate exactly the variation of canopy temper- ature with vegetation structure and environmental conditions.

Abstract:Two current configuration models of deep level native defect EL2 in GaAs, i.e. pair model As_(Ga)-As_i of Bourgoin and ternary complex As_(Ga)V_(As)V_(Ga) of Zou Yuanxi are in- troduced. The densities of vibrational state for these two models are calculated. The differ- ence between two kinds of density of state will provide useful information for final identifi- cation of the configuration of EL2.

Abstract:Pumped by 514.5nm Ar ion laser, 910nm laser and superfluorescence operation of Nd-doped silica fiber were achieved by suppressing the emission at 1080nm. The maximal output of 910nm fiber laser is 1.4mW, slope efficiency is 2.5%. The maximal out- put of 910nm superfluorescence is 0.4mW. An experimental comparison was made be- tween the outputs at 1080nm and 910nm superfluorescence. The process of change of the output from the superfluorescence to oscillatory laser in the same configuration was dem- onstrated by the experiment.

Abstract:介绍低损耗氟化物玻璃光纤的制备方法,包括高纯原料和光纤的制备,获得氟塑料包皮的氟锆酸盐玻璃光纤在2.4μm处的最低损耗为75dB/km.

Abstract:A new type PEV infrared TV system in an asymmetrically chopped mode opera- tion is designed in order to solve the problems in the standard chopped mode operation. By increasing the temperature responsivity R_i and adopting a high signal-to-noise ratio processor, the performances of the PEV infrared imaging system have been improved great- ly.

Abstract:In this paper, the general equation of IR-thermometry in single wavelength band and its perliminary analysis are given based on the concept of the Bidirectional Reflectance Distribution Function (BRDF) when the measured object is nonlambertian and there exists an independent ra- diant source in the measurement environment.

Abstract:Cloud parameters and total precipitation amount over the East-Asian Contin- ent are calculated by using an improved simultaneous physical retrieval method. The retrieval results are compared with the truth data from the brightness temperature differ- ence of both shortwave and longwave window channels. The preliminary analysis results indicate that the effect of this retrieval algorithm is definite.

Abstract:Porous silicon (PS) samples treated by chemical etching were illuminated with laser uninterruptedly in atmosphere and oxygen, respectively. The photoluminescence (PL) band of porous silicon exhibited a continuous blue shift with the time of illumination, at last it reached a stationary value. In vacuum, the sample was treated in the same way as mentioned above. But its PL band showed no shift. X-ray photoelectron spectroscopy showed that no SiO_2 was detected in the two PS layers which were illuminated in atmos- phere and oxygen, respectively. Combining it with the infrared absorption spectra measurement it is suggested that the blue shift of the PL band was attributed to the replacement of Si atom on the inner walls of PS by oxygen atom and the formation of the Si -O-Si structure.

Abstract:利用1.15μm He-Ne激光对光折变晶体KNbO_3:Fe的二波耦合实验测量,得到二波耦合增益系数为1.4cm~(-1),频率响应时间为5ms.在红外波段的初步实验结果与可见波段的规律相符.

Abstract:根据Hg_(1-x)Cd_xTe的吸收边规律,建立了从室温下体材料Hg_(1-x)Cd_xTe大光斑透过曲线确定样品平均组分x_0和均方差Δx的方法及计算软件.

Abstract:The results of photoluminescence investigation of nominally undoped bulk InP at 2K are reported in this paper.The emissions near the band-gap are carefully analyzed. It was found that the intensity of the peak due to exciton bound to the neutral donor (D~0, X) decreases while the intensity of the peak due to the exciton bound to the neutral acceptor (A~0, X) increases with increasing excitation power and its mechanism was pro- posed. Mg and Zn were identified as residual acceptor impurities in the material. The ionization energy calculated for Mg acceptor is 41.5 meV.