Abstract:A visible and infrared dual-band detection technology based on shortwave HgCdTe material is presented. A short wave HgCdTe detector is used to implement visible imaging and short wave infrared imaging respectively by changing a visible lens and a short wave infrared lens. The results show that the short wave HgCdTe detector can used for visible light imaging. This makes it possible to develop a new kind of detector which can detect visible light and short wave infrared radiation simultaneously.

Abstract:With the continuous advancement of infrared detector technologies, the demand for the third generation of infrared detector technologies is becoming obvious gradually. Because of the factors of interband transition principle, dark current restrain effect and mature material fabrication technique etc., InAs/GaSb superlattice material becomes the primary choice for the fabrication of the third generation of infrared detectors. The main methods for the fabrication of InAs/GaSb mesa-focal plane arrays are wet etching, dry etching and the combination of dry and wet etching. These three kinds of etching methods have their advantages and disadvantages. The wet etching is suitable for the fabrication of single pixel or the focal plane array with less pixels. Among the wet chemical etching, the solution with phosphoric acid performs best. The dry etching is suitable for the fabrication of large arrays with small pixel spacing. The dry etching using Cl+ and the combination of Cl+ /CH3+ exhibit good etching results. The combination of dry and wet etching is used to add wet chemical etching after dry etching in order to eliminate etching damage and hence enhance device performance. The three kinds of etching methods are presented and analyzed.

Abstract:To meet the calibration demands of infrared measurement and control developed rapidly in China in recent years, a measurement and control system for a large blackbody radiation source used for calibrating infrared detection systems with larger field-of-view angle and higher resolution is designed. The blackout radiation surface of the large blackbody radiation source is made of 7075 cold-treated forging alloy. Its effective radiation area reaches 1200 mm×1200 mm. For such a large blackbody radiation source, there are no any ready-made control methods and means which can verify whether its technical specifications meet the design requirements. According to the main technical specifications of the large blackbody, the measurement and control method is given. The accuracy of the blackbody measurement and control system is verified by the data obtained in actual measurement and control.

Abstract:Due to the factors such as inconsistent response between detection elements, changes in electronic gain and offset, and focal plane contamination and damage, the images obtained by a push-broom thermal infrared imaging spectrometer often exhibit the phenomena of non-uniformity between image columns and severe strip noise. This may affect the subsequent processing and application of thermal infrared hyperspectral remote sensing images. According to the source and cause of non-uniformity of the push-broom imaging spectrometer, a non-uniformity correction method for thermal infrared hyperspectral remote sensing images is proposed on the basis of correlation of adjacent columns. The steps are as follows: Firstly, standard moment matching correction is conducted for the original thermal infrared hyperspectral remote sensing image band by band to obtain a standard moment matching corrected image. Then, on basis of the standard moment matching corrected image, the pixels with same features in the adjacent two pixel columns are selected. Finally, by using the pixels with same feature in the two columns, the correction coefficient of the latter column is obtained though linear regression. The latter column is corrected and all columns in one band are sequentially traversed to complete the non-uniformity correction of one band image. According to this process, the non-uniformity correction of a thermal infrared hyperspectral remote sensing image is completed by traversing all bands of a thermal infrared hyperspectral remote sensing image. The method is applied to the non-uniformity correction of the image obtained by the push-broom thermal infrared spectroscopy imager. The results show that compared with the moment matching method, the average value and standard deviation of each column in the image corrected by the proposed method are more consistent with the actual situation if the non-uniformity correction effectiveness is ensured.

Abstract:A fast method for detecting the frequency stability of Back Wave Oscillators (BWOs) is proposed. The radiation from a BWO is collected and collimated by a parabolic mirror and is detected by a fast terahertz detector at the other end of the collimated light beam. The measured signal is displayed and recorded via an oscilloscope. Finally, the single-frequency output stability of the BWO is estimated according to the Fabry-Perot interference principle. The method proposed is of important application value to the performance improvement of frequency-domain terahertz spectroscopy systems with high frequency resolution.

Abstract:The imaging process of remote sensing images is easily affected by fog. At the same time, the increase of foggy weather makes the fog removal work of remote sensing images become an important part of remote sensing image data preprocessing. The dark channel fog removal method based on dark color statistical priority is widely used in the defogging of natural images. But for remote sensing images, the applicability of the dark channel fog removal method needs to be evaluated. Taking "GF-1" satellite remote sensing images as an example, the dark color characteristics of remote sensing images are discussed. The result shows that the dark channel fog removal method based on dark color statistic priority can be applied to the fog removal of remote sensing images.

Abstract:Infrared cloud images have the features of low resolution, large size and rich texture. The current research on super-resolution reconstruction is still inefficient in the optimization of algorithm efficiency and the analysis of local details. To deal with these problems, a hybrid super-resolution reconstruction algorithm is proposed and the effect of the algorithm is evaluated by PSNR combined with residual graph. This method combines the advantages of the bicubic interpolation method and the sparse representation-based method in the reconstruction of different types of images. Through variance, the image blocks in the sliding window are divided into two types of flat and edge. The bicubic interpolation method is used to reconstruct the flat image block, and the edge block is reconstructed by the sparse representation method. The experimental results show that the PSNR index of the hybrid method is 1 dB higher than that of the interpolation method and is slightly higher than that of the sparse method. Moreover, it is found in the partial observation that the noise is reduced in the plain region after reconstruction and the reconstruction time is significantly.

Abstract:Benzene is a volatile organic compound commonly found in the atmosphere. It may dissolve in water droplets, clouds and other aqueous phases. Under the irradiation of sunlight, it can undergo photooxidation reaction with the hydrogen peroxide in the aqueous phase. OH-initiated aqueous photooxidation of benzene is studied by a home-made aqueous reaction apparatus. The molecular functional groups of aqueous reaction products are measured by a Fourier transform attenuated total reflectance infrared spectrometer. The chemical components of the products are analyzed qualitatively. The experimental results show that in the absence of hydrogen peroxide, the infrared spectrum of the benzene solution after 3 hours of irradiation contains the stretching vibration absorption peaks of C-H and C=C of benzene ring. There are only benzene organic compounds in the solution, and no new product is produced. When the mixed solution of benzene and hydrogen peroxide is irradiated with ultraviolet light for 3 hours, the infrared spectrum of the reaction product solution not only has the stretching vibration absorption peaks of C-H and C=C of benzene ring , but also contains the stretching vibration absorption peaks of O-H and C-O-C bonds. These results show that OH-initiated aqueous photooxidation of benzene can form phenolic compounds and aromatic ether products. This provides experimental evidence for the study of aqueous photooxidation mechanism of benzene.