Abstract:Mercury cadmium telluride (MCT) infrared detectors are more and more used on space-based platforms and the exposure to the radiation environment in space poses a challenge to their performance. Because of the unique properties of MCT devices, the effect of space radiation on them should be taken into account specially. Currently, the total-dose-vulnerability problem in MCT devices has been solved by using CdTe passivation in MCT detector technology. However, with the improvement of material quality (e.g. by reducing the native detect concentration), the MCT devices are more susceptible to the displacement-damage-induced defects. Some published literatures about radiation effect of MCT are investigated and the research process of radiation damage effect of MCT devices and the techniques used to improve their resistance against radiation are discussed.

Abstract:Airborne multispectral scanners usually use large diameter planar blackbodies as their thermal reference sources. Because of the wide temperature range in air environment and the fact that the surface of a planar blackbody is susceptible to air flow, it is difficult to control the temperature of a large diameter planar blackbody accurately when designing an airborne multispectral scanner. A new temperature control system for planar blackbodies is designed. The system firstly uses an embedded PID algorithm based on CompactRIO to generate PWM signals and then uses the PWM signals amplified via an H bridge to control the heating and cooling of a thermopile. The experimental result shows that in air environment, the control system can adjust the temperature of a planar blackbody to the range of 20℃ of the ambient temperature with a control accuracy of 1℃. It can meet the application requirement of a thermal infrared source.

Abstract:According to the features of imaging equipment such as infrared imaging guided heads, a measurement and maintenance system based on scene generation is designed. The scene generation and measurement principles are presented and the key technologies used in the system design are analyzed.

Abstract:A three-lens polarizing CCD camera is presented in brief. After the response nonuniformity of the detector used in the three-lens polarizing CCD camera and its response nonuniformity in three polarization directions are analyzed, a correction method based on radiation calibration is proposed. The real polarization of the polarized light, the polarization of the original polarized image and the polarization of the image corrected by using the nonuniformity correction method are calculated respectively in the polarization measurement experiment. The result shows that this nonuniformity correction method can improve the analytic precision of the polarization information in an image.

Abstract:To realize the adaptive nonuniformity correction of infrared focal plane arrays (IRFPA) is very important for an advanced infrared detection system. With the increase of the complexity and scale, the correction system algorithms are more difficult to be designed. A system-level modeling method based on OO-TDPN is used to model an IRFPA nonuniformity correction system based on the BP neural network from top to bottom hierarchically. In the modeling method, the abstracted system object class is specified; then, a hierarchical model based on polymerization of object class is established for the system; finally, the Verilog language is used to specify the model and simulation is carried out in the simulation environment. The simulation result shows that the model is correct and the method is feasible.

Abstract:Using a space position measurement system to correct the image distortion caused by an unstable remote sensing platform is very common in aerial photogrammetry. The principle and method for geometrically correcting the images obtained in pushbroom mode without any ground control point are presented. The geometric correction of the images is implemented by using POS data to calculate azimuth element and by establishing collinearity equations. The method is used for PHI aerial remote sensing images in the experiment. The result shows that in the absence of ground control points, the image distortion caused by the unstable remote sensing platform can be removed quickly with the aided POS data in aerial photogrammetry. The correction accuracy of this method can meet most of the requirements in practical image application and scale mapping.

Abstract:A method for designing and constructing optical wavelet filters for 4f optical systems is proposed. Frequency domain decomposition and reconstruction wavelet filters are constructed according to the advantages of optical signals and wavelet transform and the conjugate mirror characteristics of biorthogonal wavelets. The filters can implement two-dimensional decomposition and reconstruction of images successfully when they are placed on the spectrum surfaces of 4f optical systems. In addition, both amplitude wavelet filters and phase wavelet filters constructed according to the information processing needs and sampling device properties can also decompose and reconstruct images completely. This method is an innovation in frequency filters for 4f optical systems. It is simulated by using the discrete Bior 2.2 wavelet in experiment. The experimental result shows that this method is feasible.

Abstract:The spectra of both single sophora alopecuroide seed and single cassia tora l seed in natural state are determined by using Fourier transform near infrared diffusion spectroscopy. The viability of both seeds is distinguished by using distinguished partial least squares (DPLS). The result shows that the modeling based on the average spectrum at both side surfaces is better than that based on the single spectrum at one side surface. Both sophora alopecuroide seed model and cassia tora l seed model have an identification rate of 90% at least. This study provides a new method for distinguishing single viable seed rapidly, precisely and nondestructively.

Abstract:The application of an infrared temperature measurement technique in extra-high voltage (EHV) power systems is presented. Through monitoring and analysis of the common heat failures at capacitors and isolating switches, it is found that the infrared temperature measurement technique can scan and image a large area at a long distance quickly. It has the advantages of noncontact, no power cutting, no sampling and no disintegration. To let the infrared temperature measurement technique play a better role in EHV power systems, some experiences in the use of infrared temperature measurement technique are given.