Abstract:Stirling-type pulse tube cryocoolers have become a research hotspot in recent years because of their obvious advantages of high efficiency, high reliability and long lifetime in space applications. The recent research advance in the Stirling-type pulse tube cryocoolers for space application at home and abroad is analyzed. The application prospect and development trend of Stirling-type pulse tube cryocoolers are described. Finally, the current status and key technologies of 100-Hz pulse tube cryocoolers are reviewed.

Abstract:With the rapid development of new technologies, new optical communication techniques and products are emerging in an endless stream. The optical cable and communication cable techniques will obtain unprecedented tremendous development in the future. The development trend of optical communication industry is analyzed from the point of view of the patents at home and abroad.

Abstract:To evaluate the imaging quality of a star sensor camera easily and accurately, an image acquisition system for evaluating imaging quality is designed specially. Based on a PCI bus interface, the system takes a FPGA chip as its core control logic and implements the large mass transfer of image data by using a dual SRAM buffer structure. In software, it uses a multithread approach for image displaying and storage and adds in an image evaluating module. So, it can detect the performance of the star sensor camera accurately. Several rigorous test results show that the system can operate stably and reliably and the image data collected are distortionless. When running in the case of 16 bits, the system has its peak image transfer rate up to 40 Mbps.

Abstract:To assess the potential applications of terahertz waves in space communication, radar and remote sensing, the transmission characteristics of terahertz waves in atmosphere should be studied. As the transmission attenuation of terahertz wave in the range from 0.1 to 2 THz are caused mainly by water vapor, the THz Time-Domain Spectroscopy (THz-TDS) is used to measure the transmission spectra of the air with different humidity in a 2 m long THz transmission path. The absorption spectra, transmission rate and weak attenuation widows of water vapor in the frequency range from 0.1 to 2 THz are obtained.

Abstract:With the development of infrared countermeasure technologies, the design of infrared imaging precision guided weapons meets more and more practical difficulties. To improve the adaptability of infrared imaging precision guided weapons in a complicated battle field, the characteristics of targets are studied by using the main-in-the-loop technology in practical projects. A project scheme which can provide support for the criteria optimization of Auto Target Recognition (ATR) is proposed. The scheme is of referential value to the improvement of the independent design ability of the infrared imaging precision guided weapons in our country.

Abstract:To measure the characteristics of a target in a complex environment is extremely difficult. The components and features of a complex infrared environment are studied. The influence of the complex environment on the measurement of infrared characteristics of a target is analyzed systematically. The measurement condition and requirements are proposed. Finally, the methods for measuring and studying the infrared characteristics of a target in a complex environment are discussed in detail. The result is of referential value to the measurement and study of the radiation characteristics of targets.

Abstract:Because of many factors, the infrared star images acquired in the daytime have a low signal-to-noise ratio and a nonuniform background. The star targets in the images can not be extracted by using common filtering methods. Currently, the common morphological method is also not ideal for the processing of star images. Firstly, the background characteristics are analyzed and the multi-frame superimposition method is used to reduce the random noise, so as to improve the signal-to-noise ratio. Then, setting a threshold, the background in the superimposed star image is removed and the image only containing targets and noise is obtained. Finally, the star image is processed by using a template similar to the star in size according to certain rules so as to separate the targets. The experimental result shows that this method is more efficient in star target separation.

Abstract:The dimension reduction is of significance to the interpretation of hyperspectral images. The classical Principal Component Analysis (PCA) method based on Second-order Statistics (SOS) may lose the signals of small targets during dimension reduction. To solve this problem, the PCA method is extended by using high-order statistics as projection indexes and a hyperspectral image dimension reduction method based on multi-index successive projection is proposed. The method incorporates the features of the non-orthogonal projection while retaining the advantages of the PCA method. It can keep the abnormal signal components in the dimension-reduced space. The experimental result of the real hyperspectral image data shows that this method can extract more complete signal subspace than the PCA method.

Abstract:Both radial pattern characteristic parameters and circle pattern characteristic parameters are constructed for near infrared (NIR) star objects after their distribution characteristics are analyzed. The characteristic parameter matching recognition is carried out both for the characteristic library obtained in construction and for the starry sky navigation library based on the standard starry sky coordinate data. The result shows that this method is of a certain value in practical application.