Abstract:The growth of high-quality epilayers is necessary for high-performance HgCdTe infrared detectors. Due to perfect lattice match with HgCdTe, bulk CdZnTe is considered as the ideal substrate. Crystal materials should achieve very high performance in terms of subgrain boundary absence, low dislocation density, homogeneous zinc distribution, and low micro-defect density, which is essential for acquiring excellent image quality. In order to control the quality of HgCdTe epitaxial layer, Sofradir uses CdZnTe crystals grown by itself as the substrate, thereby achieving high performance imaging. In fact, the whole production process can be improved by mastering the entire manufacturing chain from raw materials to focal plane array (FPA) including all front-end and back-end steps. The method for translating the latest process improvements into detector image quality and reliability improvements with a focus on front-end processes (substrates and epitaxial layers) is introduced. Under the collaboration between Sofradir and CEA-LETI, the correlation between substrate microscopic defects and FPA image quality is firstly demonstrated. Though a large number of characterizations for each process step, including IR-microscopy for the substrate inspection, chemical revelation of dislocations and X-ray double-crystal rocking curve mappings for the epitaxial layer, the overall optimization of this process is achieved. Image quality detection in terms of effective pixel rate and excess noise is completed. Finally, in addition to improving the process, understanding how each key step affects the subsequent steps and translates them into the final image quality is helpful for sorting units in the correct process step, which serves yield and product quality. These advantages of the Sofradir′s vertical integration model are demonstrated on the mid-wave infrared and short-wave infrared technologies.

Abstract:Based on the study of directional derivative characteristics of Facet model， a detection method for infrared weak targets is proposed. This detection method uses local relative extreme differential value at the multi-directional lines to calculate the significance of small target, which is very effective for fast extraction of targets under complexbackground. This method is based on the theory of single frame detection of weak target. Firstly, the Facet wizard number characteristics of the original image are calculated. Secondly, in the local part of the Facet wizard number feature graph, the relative extreme difference contrast is calculated along the current direction. Then the relative extreme difference contrast in each direction is fused to obtain the final significant image. Finally, the target is extracted with appropriate threshold segmentation for the final significant image. The experiment result shows that the proposed algorithm has high signal-clutter gain and background inhibitor for complex infrared weak target images. In addition, the computational complexity of the algorithm is low and can be calculated by using two-dimensional convolution acceleration. As a good real-time algorithm, it is beneficial to the engineering implementation of various processor platforms.

Abstract:The environment of modern warfare is becoming more and more complex, and the single guidance mode is vulnerable to effective interference, while the composite seeker can exploit the advantages of various guidance modes and make them complement each other. According to the technical characteristics of infrared imaging sensor, active millimeter-wave radar and passive radar, the work processes of infrared imaging/active millimeter-wave radar composite seeker and infrared imaging/passive microwave composite seeker are analyzed. In order to improve the anti-nterference ability of composite seeker, by combining with the actual process of anti-ship missile, millimeter-wave radar or passive radar is used at long distance, while infrared target features are exploited to distinguish between interferences and ship targets at short distance, forming a terminal guidance strategy suitable for infrared imaging/active millimeter-wave radar composite seeker and infrared imaging/passive microwave composite seeker of anti-ship missiles.

Abstract:In view of the shortcomings of the traditional optical fiber loss tester, such as long preheating time and great influence of temperature change on the output power of the infrared light source, a scheme of modulating the infrared light source with sine wave signal was proposed. This method can effectively solve these problems and achieve good test results. Firstly, three kinds of sinusoidal wave signal generation methods were introduced, among which the direct digital frequency synthesis (DDS) method produces sinusoidal wave with high frequency resolution and frequency stability. Secondly, the internal structure and conversion principle of DDS chip AD9832 were introduced. The sinusoidal wave signal generated by the DDS chip was applied to the infrared optical loss tester. The changes of the infrared light source power before and after the sine wave signal modulation and before and after the preheating were compared. The results show that the stability of infrared light source after sinusoidal wave modulation is better than that before modulation, and it is more convenient for users to quickly measure the optical fiber loss.

Abstract:In the Brillouin optical time domain reflectometer (BOTDR) fiber-optic sensing system, the scattering signal from Brillouin back scattering is very weak, especially the Brillouin scattering signal at the far end of the fiber, the signal-to-noise ratio is very poor and is very difficult to analyze. A method of improving Brillouin signal quality based on cross-correlation theory was presented. Through cross-correlation with ideal Brillouin scattering spectrum, the difficulty of strain analysis for very weak Brillouin scattering signal at the far end of optical fiber was reduced. It was verified by experiments that this method can effectively improve the signal quality of strain distribution data and the strain sensing accuracy of BOTDR when the signal-to-noise ratio is poor.

Abstract:Underground oil pipeline monitoring is one of the important contents of oil safety work. According to the heat source characteristics of oil pipelines, a remote sensing monitoring study of underground oil pipelines based on unmanned aerial vehicle mounted thermal imaging cameras was carried out. The infrared image-based pipeline identification, pipeline bare and shallow buried identification were realized. And the comparative analysis between infrared images and visible remote sensing images of the same pipeline was performed. The feasibility of infrared remote sensing imagery in the safety monitoring of underground oil pipelines was verified.