Abstract:The determination of the cloud parameters in atmosphere is of importance to the study of atmospheric physics and climate. These parameters are difficult to be derived directly in actual measurement and should only be derived after some related measurable physical factors are retrieved. Through analysis of space-based cloud observation, it is found that atmosphere path length, cloud-top temperature or pressure and the micro composition of different clouds can be used in the remote sensing and retrieval of cloud-top height. Some references show that the practical methods can be divided into two classes: the method using the geometry of imaging and the one using spectral radiation characteristics. The former relies on the space orientation of the light source, target and sensor controlled precisely during imaging and the latter relies on the quantitative radiation values of ground objects. When combined with the multispectral or hyper-spectral technology, they can derive abundant cloud information. Eight methods are presented.

Abstract:The basic characteristics, such as critical thickness and superlattice stability, bandgap and energy band changes, increased refractive index and plasma dispersion effect, of SiGe strain layers are reviewed. Two ways to relieve stress, including dislocation and surface undulation, are summerized. Finally, the progress and application prospects of SiGe/Si strain quantum-well photodetectors and infrared focal plane array photodetectors are presented.

Abstract:Spectroscopic ellipsometry is a non-distructive spectroscopic technique. To find the optimal Microwave Plasma Chemical Vapour Phase Deposition (MPCVD) condition of diamond thin films, the infrared optical properties of diamond thin films are characterized by using an infrared spectroscopic ellipsometric spectrometer. The influence of substrate temperature and chamber pressure on the infrared optical properties of diamond thin films is analyzed. It is found that the optimal infrared spectroscopic ellipsometric properties and an average refractive index of 2.393 can be obtained for the diamond thin films with a constant methane concentration, a substrate temperature of 750℃ and the chamber pressure of 4.0kPa. The result shows that the optical properties of diamond thin films are closely related to their quality.

Abstract:A resistorless current reference which has low temperature drift is designed for novel uncooled infrared focal plane array (IRFPA) readout circuits. First, the reference voltage VREF is obtained from a resistorless bandgap reference circuit. Then, the reference voltage is applied to the gate of a NMOS output transistor and is adjusted to force the NMOS output transistor to operate at zero TC (ZTC) point and generate a temperature independent reference current IREF eventually. The method is simulated in the CSMC 0.5μm CMOS process by using the Spectre software. The simulation result shows that the fluctuation of the output current is less than 4μA in the temperature range from 0℃ to 120℃. When a 3.3V power supply is used, the circuit just has its power dissipation of 0.94mW.

Abstract:Temperature unstability is one of the important factors affecting the performance of an uncooled infrared focal plane detector. A MAX1978-based temperature control system with a closed-loop control structure is designed. The control system drives a thermoelectric cooler module via an external proportional-integral-derivative compensation network and the temperature of the detector is controlled. The experimental result shows that the system can effectively control the temperature of the focal plane detector with an accuracy of 0.06℃.

Abstract:The 1553B bus is a bus standard widely used in information transmission among airborne instruments. The 1553B bus protocol is presented in brief. Taking a certain airborne visible light camera as an example, the compoments of the camera system, their functions and system joint mode are presented. Both a TMS320F2812 chip and a B61580 chip are used in the design of a 1553B communication module and the procedure to embed the 1553B software module in the main control software of the camera is illustrated. This method is stable and reliable and can meet the design requirements of the camera system.

Abstract:Temperature variation has influence on the imaging uniformity of an uncooled infrared focal plane. The reason is that the bias of the uncooled infrared focal plane may become unstable after it is affected by temperature variation, resulting in a subtle deviation in the output of the focal plane. Thus, the quality of the image formed by the focal plane is degraded. To solve this problem, a method which uses a FPGA to receive the output feedback from a ADN2850 is proposed. Because the data can be compared with the preset value by using this method, the data difference from the preset value can be corrected continuously. Therefore, the bias circuit can be kept stable and the imaging quality of the infrared focal plane can be improved. This method has the features of high precision and fast response.

Abstract:A dual threshold leading edge timing discrimination method for pulsed laser ranging is presented. The timing error caused by the amplitude variation of the received pulse is analyzed. The dual threshold leading edge timing discrimination method is used to generate a stop signal for flight time measurement and a time point signal related to the pulse amplitude. A high-precision interval measuring chip is used to measure the actual flight time of the laser pulse and the time interval related to the pulse amplitude and is also used to compensate the drift error caused by the timing discriminator. As a result, the ranging precision of $\pm$3cm is obtained. Compared with other timing discrimination methods, this method has the features of no AGC unit, simple circuit structure and wide dynamic range. Moreover, it can still compensate the drift error even when the pulse amplitude is saturated.

Abstract:A dual-index sequential analysis method for analyzing the common and variant peak ratios of bulbus lilii in infrared fingerprint is established. The common and variant peak ratios of ten kinds of samples from different regions are measured and analyzed. The result shows that some bulbus lilii samples from several neighbouring regions all have higher common peak ratios and lower variant peak ratios in their infrared fingerprint. Some samples from several other neighbouring regions have the common peak ratios higher than 80.0% and variant peak ratios lower than 25.0%. Some samples from several regions which are far away from each other have the common peak ratios lower than 60.0% and variant peak ratios lower than 15.8%. This analysis method is simpler and more effective than the chromatographic analysis method. It can discriminate the bulbus lilii from different regions accurately and will become a new method for evaluating the quality of traditional Chinese medicine.