Abstract:According to the theoretical methods and the situation investigated, the development and main application fields of infrared detection technology are presented. After analyzing the infrared radiation of stealth aircrafts, the tail nozzle radiation, tail flame radiation and skin heat radiation of stealth aircrafts are studied. Then, a specific infrared stealth method is given for each kind of radiation. Finally, a conclusion is given and more advanced infrared detection means against infrared stealth technologies are expected to satisfy the demands of modern military.

Abstract:To achieve the spectral imaging of an object in a large field of view, the technology path which combines a two-dimensional pointing mirror with a staring spectrometer is usually used. However, when the two-dimensional pointing mirror is used to image close objects, the image rotation and distortion generated at different azimuths and pitch angles are different. Therefore, it is necessary to establish an optical transfer model among the actual object coordinate system, the detector image coordinate system and the azimuth and pitching angle firstly. According to the optical transfer model, the transformation relationship between the transmission distortion image and the real image can be obtained. Then, after the transmission distortion image is corrected by perspective transmission, image stitching can be implemented on the large field-of-view image. The experimental results show that the method is feasible, easily implemented and stable.

Abstract:To meet the application needs of wide field and wide spectrum of earth environment remote sensing, a center without obstructing is realized by means of field off-axis on the basis of coaxial three-mirror optical systems. An optical system with a Cook three-mirror structure is designed. The optical system has its focal length of 120 mm, F number of 3.5, operating wavelength of 0.4 to 1.65 μm and pixel size of 7.5 μm. it realizes the 30°×4° large field of view without any free-form surfaces. In the optical system, the primary mirror is a 6 times hyperboloid; the second mirror is a secondary flat ellipse and the third mirror is a 4 times flat ellipse. The system has its Modulation Transfer Function (MTF) greater than 0.6 at the Nyquist freaquency in the whole field of view, which is close to the diffraction limit. Its RMS dispersion spot diameter is less than the pixel size of the detector and its distortion is less than 2.5%. These results show that the system has excellent imaging performance.

Abstract:To study the damage of a Mercury Cadmium Telluride (HgCdTe) film caused by its thinning technology is most important. By using the Scanning Electron Microscopy (SEM) to study the damage layer of the HgCdTe film after thinning, valuable experimental results are obtained. These results are of great significance both to the understanding of the damage of HgCdTe films caused by thinning technology and to the subsequent optimization of the related thinning technology.

Abstract:Large area array infrared detectors are the core components in infrared remote sensing instruments. Most of them are composed of spliced small-scale area array detectors and are integrated on Dewar cold platforms to form Dewar assemblies. The stress state of a detector after being integrated on the Dewar cold platform is a key factor affecting the performance and lifetime of the chip. The thermal output of a strain gage when the detector is both in the free state and in the Dewar is tested at low temperature. The difference between the two values is used to characterize the extra strain after the detector is integrated with the Dewar cold platform. Taking a 2000×512 detector assembly as an example, the test verification and analysis are carried out. The result shows that this method is feasible.

Abstract:As signal sources, the infrared laser light sources with wavelengths of 850 nm, 1310 nm, 1490 nm, 1550 nm and 1625 nm have wide applications in the test of optical fiber communication systems. These laser light sources need stable output light power. Usually, to meet the test and correction requirements in different cases, an optical attenuator with optical attenuation slices is used to adjust the output light power of the light source. By analyzing the characteristic curves of laser output power and driving current, a method for using voltage-controlled current on a circuit is proposed. Thus, a stable laser light source with adjustable output light power (the adjusting range is up to 30 dB) is realized. By this method, the use of optical attenuators can be reduced effectively, the number of the instruments to be used can be reduced, the test efficiency can be improved and the test cost can be reduced.

Abstract:To realize high precision angle measurement on a scanning control machine, taking an absolute round inductosyn as the angle measuring sensor, a high precision and high stability angle measuring system is designed. Through the design of hardware circuits and FPGA program, high precision and high stability angle measurement and high reliability absolute angle measurement are achieved respectively. The actual experimental results show that the system has strong anti-interference ability. Its stable angle resolution is up to 0.1'' and its angle pointing accuracy is better than 1.1'' (3σ).

Abstract:To improve the accuracy of automatic extraction of object information in infrared remote sensing images while avoiding the inefficiency of manual extraction of remote sensing information, a remote sensing information extraction algorithm based on the UNet deep learning model is proposed. The algorithm is used to segment five kinds of object feature information including road, building, tree, farmland and water in infrared remote sensing images. Firstly, a small number of high resolution training data are cropped randomly and corresponding data enhancement processing is implemented on them. Then, a UNet deep learning model is established and is used to extract the feature information in remote sensing images automatically. The model is trained by using the cross-entropy loss function and Adam optimization algorithm and is used to extract the object information in five remote sensing images accurately. Finally, the classification result is evaluated by using the Jaccard index. The experimental results show that this method can fully fuse the high resolution infrared remote sensing image information with the visible remote sensing image information. It has higher accuracy in positioning and classification for various objects.

Abstract:The temperature correction method of a thermopile-type terahertz detector is proposed. By this method, the influence of ambient temperature on the zero drift and responsibility of the detector can be reduced effectively. Firstly, two thermopile detectors with same specifications output in parallel. One of the detectors is used as the main detector and the other one is used as the reference detector. Thus, the zero drift caused by external disturbance is reduced effectively. Secondly, a temperature-compensated device containing a temperature transducer is introduced around the thermopile detector. By using a FPGA controller to obtain ambient temperature in real time and incorporating the responsibility correction coefficient of the detector, temperature compensation is completed. The results show that the zero-drift noise is reduced from 3.76 mV to 0.49 mV and the responsibility variation caused by temperature drift is reduced from 19.5 mV/W to 2.7 mV/W. This temperature correction method can greatly reduce the impact of temperature noise and effectively improve the performance of terahertz detectors.