Abstract:Monitoring the resources, ocean and atmospheric environment on earth by space remote sensing can provide predictive information and security for human's living environment. Infrared remote sensing instruments are the main detection payloads for earth observation satellites. With the improvement of the performance of infrared detectors and system integration technology, the detection capability of space-based infrared remote sensing instruments is developing greatly. Various kinds of high-performance earth observation satellites launched all over the world over last five years are presented. The application status, function and characteristics of some important infrared remote sensing instruments are summarized. Their future development trends are analyzed.

Abstract:Compared with the infrared photon detectors fabricated from other materials, the infrared detectors fabricated from mercury cadmium telluride (MCT) have several advantages of highly tunable bandgap, high quantum efficiency and R0A approaching the theoretical limit. The main drawback of the MCT detectors is that they have need to use cryogenic cooling to suppress the thermal-induced free carriers resulting in noise. It is desirable that the MCT detectors can operate at high operating temperatures (HOT) without sacrificing their performance. The HOT/MCT detectors are designed mainly to suppress Auger processes so as to reduce noise and degrade cryogenic cooling requirement. Starting from related basic concepts, the understanding of the physical mechanism of HOT/MCT is discussed and the development of HOT/MCT detection technology in recent years is presented.

Abstract:Electron Multiplying Charge Coupled Devices (EMCCD) are new high-sensitivity image sensors. In recent years, EMCCD cameras are used in the field of low-light detection more widely. To use the new EMCCD in a low light camera, a low light imaging system with strong detection ability, fast data updating ability and an integrative fiber optical interface is designed. The design method of the EMCCD camera is studied mainly. The operation principle of the EMCCD is explained. The design scheme of the EMCCD low light camera based on a TC253SPD-B0 chip is presented. The performance of the integrative low light camera is verified in both an imaging experiment and a signal-to-noise ratio measurement experiment. The results show that the camera not only can implement the data transmission in a distance of more than 20 km and the frame frequency of 30 f/s, but also can implement detection under the condition of low light. It has a higher signal-to-noise ratio.

Abstract:Currently, since most of mirrors for space optical cameras are made of brittle materials, they are suitable to be fixed by cementation with simple configuration. However, how to control cementation quality and how to reduce or remove the transmutation of the mirror due to the stress of cementation are very important. For the mirror optical epoxy glue cementation frequently used in space optical cameras, because the measures such as reasonable determination of cementation parameters, control of cementation thickness and use of proper optical epoxy glue technology are taken, the stress due to the cementation of the mirror is reduced and the surface figure of the mirror is kept unchanged before and after cementation. The test result shows that this cementation method is reasonable and feasible.

Abstract:To satisfy the space position requirement of a space camera to be installed onboard a satellite and avoid the sympathetic vibration between the space camera and the satellite, a cabin structure is designed. The design uses a carbon fiber with good mechanical and technological properties and a truss structure with a reasonable topological structure form. The section sizes of the pole in the cabin structure are optimized by using a computer simulation test method and a cubic spline interpolation. The result shows that both the dynamic features and the total mass of the cabin structure satisfy the design requirements for the section size of 28 mm×28 mm×3 mm.

Abstract:A method for predicting the minimum resolvable temperature difference (MRTD) of an infrared imaging system is proposed. The method is based on the linear system theory. It uses the modulation transfer function to establish an infrared imaging system model for simulating and generating standard four-bar patterns with different spatial frequency (it has an aspect ratio of 7:1). By analyzing the two-dimensional (horizontal and vertical) imaging quality of the four-bar pattern and introducing a contrast correction factor, the temperature difference between the four-bar pattern and the background output from the system is acquired. Then, the threshold input contrast transference is used to obtain the MRTD of the system. The simulation results show that the MRTD predicted by this method is coincident with the actual measurement value.

Abstract:The thermal infrared anomaly characteristics of 14 moderately strong earthquakes happened in the mainland and adjacent sea of China are extracted and analyzed by wavelet transform and relative power spectrum calculation according to the remote sensing brightness temperature data from geostationary meteorological satellites FY-2C/2E of China. The anomaly characteristics include: (1) Anomalies have obvious characteristic periods. The periods for mainland earthquakes are 13 days and 64 days and those for sea earthquakes are less than 32 days. The earthquakes with similar epicentral positions have the same characteristic periods; (2) Maximum anomaly amplitude is obvious and easy to be identified. Most of the amplitude is more than 8 times, and even up to 20 times; (3) Earthquakes are located in the interior and edges of anomaly regions. The transition areas in which anomalies appear and disappear are possible epicenters; (4) Earthquakes happened in arid areas have longer characteristic periods and those happened in wet areas have shorter characteristic periods; (5) The relationship between maximum anomaly occurring time and earthquake happening time and the relationship between anomaly peak and amplitude are not clear yet; (6) By comparison, mainland earthquakes and sea earthquakes have the similarity in above relationships, but their characteristic periods and anomaly areas are different.

Abstract:Unstable rocks may often locate on steep slopes. Some stones separated by cracks are very large in volume and some stones are just boulders on steep slopes. Because the volume and unfavorable structure surface binding characteristics of a certain dangerous rock body can not be obtained easily by traditional measurement methods, prediction of the instability mode and dangerousness of dangerous rocks has been a challenge for the investigation of geological hazard to be caused by dangerous rock bodies. 3D laser scanning technology is a new technology developed in recent years. Because of the advantages of fast, accurate and non-contact measurement, it has been used in various fields. Some examples of using a 3D laser scanning technology to scan dangerous rock bodies are presented. The results show that the technology can perform well in the measurement of dangerous rock bodies and can overcome the shortcomings of traditional measurement methods.

Abstract:Aiming at the infrared ship target detection against the background of sea, a saliency detection method based on frequency modulation is improved. First, a Gauss high pass filter is used to process an infrared image, so as to restrain the effect of sea clutter. Then, the saliency detection method based on frequency modulation is used to detect the ship target. The result shows that the infrared ship target is more complete when it is detected by the proposed method. The resolution of the saliency figure obtained is higher. The method can meet the real-time requirement.