Abstract:Heterodyne detection laser Doppler radars are widely used in wind measurement, fluid speed measurement and landing navigation etc because of their high measurement accuracy and good velocity direction discrimination ability. The operation principle, error sources and system noise of a heterodyne detection laser Doppler radar are analyzed and the simulation results of signal-to-noise ratio and detection accuracy of the system are given. An all fiber heterodyne detection laser Doppler radar system is developed. The speed measurement experiment is made on it by using a high precision motion target simulator. The experimental result shows that its measurement accuracy is better than 6.7 cm/s and is independent of velocity. This result is consistent with the simulation result.

Abstract:The multi-resolution analysis fusion method and multi-scale geometric analysis fusion method are used for fusing the infrared cloud images and water vapor cloud images from FY-2E meteorological satellite. Moreover, the mean mutual information and Xydeas-Petrovic index are used to evaluate the performance of different fusion algorithms qualitatively and quantitatively. The results show that the visual effect of the fused image is actually improved relatively to the raw images. The fused image contains more abundant information about the cloud and the texture and hierarchy of cloud are improved as well. In light of two objective evaluation indexes, the multi-scale geometric analysis fusion method is better than the multi-resolution analysis fusion method in fusion effectiveness.

Abstract:Using a single image to acquire the depth information of an object is a great challenge in monocular vision. According to the defocusing principle of a defocused image, a single defocusing diffusion coefficient is deduced. Then, in the light of the correlation of different areas in the single image, a constraint condition for replacing the secondary imaging is proposed. In the constraint condition, an image detection method is used to detect two areas to be measured and the diffusion of the images of two areas is implemented respectively by incorporating the anisotropic diffusion model and area diffusion coefficient of the defocused image. Finally, a minimum energy function is used to solve the anisotropic image diffusion equations for each measured area and hence the depth of the object in the area is obtained. In accuracy, the experimental result is similar to that of the traditional method in which two defocus images are used to obtain the depth. Since the camera parameters need not to be adjusted in the measuring process, the operability of monocular ranging is improved. This method is a powerful alternative to the existing vision measuring methods and will have broader application prospects.

Abstract:To assess the quality of the retrieved O/N₂ images from FUV remote sensing, the retrieval quality of the obtained FUV O/N₂ images is analyzed in RGB and HSV color spaces respectively when the images published at the GUVI website are used as the reference images. The similarity of the retrieved images to the reference images are assessed by using the evaluation functions in the RGB color space and the HSV color-space histogram cross matching method. The images to be assessed are highly consistent with the reference images. The result shows that it is feasible to assess the retrieval quality of O/N₂ images from FUV remote sensing in the view of images.

Abstract:To study the mechanism of long-wavelength infrared (LWIR) polarization detection, a mathematical model is established for the detection system according to its actual detection structure. Various factors in the structure are analyzed theoretically and calculated mathematically by using the related formulas. The influence of the components in the model on the final polarization detection result is obtained and the corresponding methods and measures for improving the detection precision of the whole system are proposed. The mathematical model and theoretical analysis result provide a certain theoretical basis for the study of the whole LWIR polarization detection system and provide referential data for the further experimental verification and practical application.

Abstract:With the improvement of the modern photoelectric device technology and the increase of the pixels in a focal plane array device, the total thickness variation (TTV) of wafers in a grinding process is improved because of more and more attention paid to large size wafers. To meet the requirements of large size wafers, their TTV values are reduced in the grinding process. After the TTV values of the wafers obtained under different grinding conditions are analyzed, a reasonable grinding procedure is established.

Abstract:The components and operation principle of an infrared imaging guided system are presented. The mechanism of an infrared imaging guided missile in smoke jamming is analyzed. A method for comprehensively evaluating the combat efficiency of infrared imaging guided missiles in smoke jamming is given. The method is based on digital simulation. It can obtain the kill probability of a missile in smoke jamming by combining the field test with the fuzzy analytic hierarchy process. It is of significance to the evaluation of the combat efficiency of infrared imaging guided missile systems.

Abstract:In the view of a histogram of near infrared starry sky images, the characteristics of the histogram are analyzed. The threshold for image segmentation is determined by fitting the low area of the histogram with a Gaussian function. The results obtained with different thresholds are compared. When ten objects which have the largest area in the eight-neighborhood are selected as the navigation objects, less data are used. Because the calculation amount of a computer is reduced greatly, both navigation effectiveness and recognition speed are improved.