Abstract:Detecting the targets in near space will play a very important role in the future wars. A design scheme for detecting the target vehicles in near space by using a ground-based passive optical detection system is proposed. The spectral characteristics of the target vehicles in near space are analyzed in detail. The necessity of using multispectral means to detect the target vehicles is indicated for the system. The structure of the detection system is given. The design specifications of the detection system are analyzed in both the focal length of the optical system and the contrast. It is assumed that the diameter of a target is 20 m and the sun angle is 15°. When the optical system has its focal length of 280 mm, the contrast between the target and the background is 0.33. It shows theoretically that this system scheme is effective and feasible.

Abstract:A method for calculating the straight length and the shortest arc line length between two points according to the longitude and latitude information given by satellite positioning data is presented. The operation range between an infrared detection system and a target is the length of a straight line. It can be calculated according to the longitude and latitude information of the infrared detection system and the target. If either of the infrared detection system and the target is moving (e.g. ground-to-air or air-to-ground) or both of them are moving (e.g. air-to-ground), the operation range of the infrared detection system can be calculated by using this method.

Abstract:To analyze the error produced when the atmospheric parameters are inverted by using the classical physical method, the influence of channel characteristics, background error, observation error and instrument noise etc on inversion accuracy is analyzed by using the Bayesian principle during the inversion of atmospheric parameters. An index for quantitatively measuring the contribution of channels to the inversion accuracy of atmospheric parameters is proposed. Taking this index as a criterion, a channel selection scheme is designed and demonstrated when the atmospheric temperature profile is inverted by using high spectral resolution data. 300 channels which have the greatest contribution index are selected from 8461 channels of the second-generation Infrared Atmospheric Sounding Interferometer (IASI) launched in 2012 and are compared with the application channels published by AAPP. The result shows that the proposed channel selection method is effective and feasible for the inversion of atmospheric temperature profile.

Abstract:Starting from the Schrodinger equation, the influence of different Al composition and different temperatures on the absorption spectra of wide quantum well infrared photodetectors (QWIP) is studied. It is found that when the Fermi level is fixed, the ground state bound energy of the quantum well may increase with the increasing of the Al composition and the corresponding absorption spectral peak tends to move toward the short wave. In addition, the influence of the ambient temperature on the response spectra of AlGaAs/GaAs QWIPs is negligible. After theoretical calculation, the rule of the absorption spectrum of an AlGaAs/GaAs QWIP changing with quantum well width, Al composition and temperature is given.

Abstract:In the field of infrared quantitative defect detection, the existing theoretical methods may bring about greater errors. In addition, the theory which uses the heat conduction method to detect defects is only limited to the detection of surface defects. On the basis of the heat conduction theory for surface defect detection, a heat conduction theoretical model for detecting internal defects in specimens is proposed.

Abstract:An adaptive Canny operator edge detection method for detecting the edges of infrared images of a ship is proposed. In the method, the maximum local standard deviation of an image is used to set Gaussian filter scale parameters for the reference value. Then, the maximum variance method based on a gradient histogram is used to calculate the high and low thresholds of the Canny operator so as to implement the automatic detection of edges. The experimental result shows that the ship edges detected by this method are clear and continuous with less noise. The method is better than the traditional Canny operator edge detection method and has a good engineering applicability.

Abstract:The image preprocessing requirements of an infrared image processing system are presented. An Otsu method based on gray gradient mapping function is proposed for the target misclassification occurred easily in the traditional image segmentation algorithm. The method can overcome the shortcoming of the traditional Otsu method based on gray histogram, which can not make use of the local and boundary information in an image. By combining the gradient information with the gray information of pixels, the target can be well separated from the background. The simulation result shows that the algorithm meet the expected specifications and can implement the preprocessing of infrared images.

Abstract:It is impossible to implement all-weather infrared stealth of a ship by using a coating with a changeless emissivity. Taking the radiation contrast less than 0.04 of a target and the background as a judgment criteria, the variation range of the target surface emissivity required for infrared stealthy is obtained by calculating and analyzing the infrared characteristic models of the target and background. A method for changing the average surface emissivity of a target by using electrochromic materials is proposed. Compared with the common infrared stealthy coating with a fixed emissivity, the stealthy efficiency of the infrared stealthy coating with a changed emissivity is improved greatly. It can meet the all-weather infrared stealth requirement of a target basically.

Abstract:The ideas of Verification, Validation and Accreditation (VV&A) and Test and Evaluation (T