Abstract:In As/Al Sb tw o-dimensional electron gas ( 2 DEG) structures w ere successfully grow n by M BE equipment. 2 DEG characteristics of samples w ere improved by optimizing the the thickness of Al Ga Sb buffer layer, the thickness of In As/Al Sb interface layer, and the thickness of Al Sb spacer. The In As/Al Sb 2 DEG structure sample w ith an electron mobility of 20 500 cm2/V·s and a sheet electron density of 2. 0 × 1012/cm2 w ere achieved w hen the thickness of Al Sb spacer is fixed at 5 nm. It provides a reference for the research and fabrication of In As/Al Sb HEMT.

Abstract:In the implementation of field effect transistor ( FET) terahertz ( THz) detectors, the integration of properly designed planar antennas could effectively enhance the coupling efficiencies betw een the transistors and THz radiation, thus improving the responsivities of THz detectors. A method to design the planar antenna w hich is based on the simulation of channel electric field at the gate edge of FET is reported here. This method is suitable for the situation w here the input impedances of FETs may not be conveniently obtained in the THz regime. The validity of this method in the antenna design is confirmed by the measurements of the fabricated Ga N/Al Ga N FET THz detectors. The maximum responsivities of the bow tie detector and the dual-dipole detector are obtained at170. 7 GHz ( 1 568. 4 V/W) and 124. 3 GHz ( 1 047. 2 V/W) respectively, w hich are close to the simulation results of channel electric field at the gate edge of the bow tie detector and the dual-dipole detector.

Abstract:An improved equivalent circuit model for graphene spiral inductors based on physical principles is presented in this letter. The model is a π-circuit w ith additional parallel RC netw ork in the series branch. A parameter extraction approach for proposed model, w hich combines the analytical approach and empirical optimization procedure, is also investigated. Good agreement is obtained betw een the simulated and measured S-parameters up to 40 GHz.

Abstract:In this report, series of annealing experiments under different temperatures of Au-doped Hg Cd Te covered by Cd Te have been implemented. The annealing process can improve the crystal state of electron beam evaporated Cd Te layer. The interface betw een Cd Te and Hg Cd Te can also be modified. The Au doping distribution in Hg Cd Te did not change after the vacuum annealing at 240℃ and300℃. How ever, the Au element diffused into the Cd Te cap layer significantly, leading to a higher concentration of ( 5 ~ 6) × 1016 cm-3. On the other hand, the concentration of mercury vacancy after various annealing processes w as different due to the temperature-dependent diffusion mechanism. In general, the carrier concentration measured by HALL effect varied from 2 × 1016 cm-3 to 5. 5 × 1016 cm-3, when the annealing temperature was increased from 240℃ to 300℃.

Abstract:The impedance matching model is built to optimize the performance of the PTC from both cold finger and compressor. Based on the thermoacoustic theory, a 1-D simulation model of the 30 K PTC is built by using Delta EC softw are for optimizing the coupling w orking parameters of the cold finger and compressor. The effects of the regenerator material, the inertance tube and the reservoir on the impedance of the cold finger are investigated theoretically. The test system is set up and the results show that the low est temperature of 24. 24 K and cooling pow er of 1 W at 30 K w ith electric pow er of227 W can be obtained, w hich satisfy the applications of the space infrared detectors.

Abstract:After launching Feng Yun-4 ( FY-4) , the on-orbit test to the satellite is done, the M TF of the solar reflectance bands is better than 0. 14, 0. 17 and 0. 22, that is better than the designed capability.The noise test is based on the black-body on the apparatus, the noise for all the infrared bands is less than 0. 2 K @ 300 K, the noise of the best band is about 0. 06 K @ 300 K. The calibration precession of infrared band is validated by the GSICS algorithm, the bias of all the infrared bands are less than 1 K comparing to IASI, the bias of the best band is about 0. 3 K @ 290 K. The RGB image carries more information than the gray image, although the AGRI has 6 solar reflectance bands, there are no real red, green and blue bands of human beings, a new algorithm generating RGB image for AGRI is suggested, based on the character of 0. 82 band, a very beautiful RGB image w hich is good to human beings is generated, that improves the multi band use for AGRI.

Abstract:Current polarization detection is mainly based on the polarization state of at-sensor radiance, w hich can enhance objects of interest or restrain background disturbance qualitatively. There is only empirical linear method for polarized reflectance retrieval of ground objects, w hich is inadequate in terms of adaptability and real-time capability under varied observation conditions. A polarized reflectance retrieval method based on polarized atmospheric radiative transfer model is hereby proposed. A lookup table ( LUT) is established by using the radiative transfer model to illustrate the relationship among polarized reflectance, observation condition and at-sensor polarization state. Polarized reflectance can then be retrieved using the LUT combined w ith numerical calculation. Results show that the retrieval accuracy of polarized reflectance of typical ground objects can be up to 90%.

Abstract:In this paper, the characteristics of the flickering pixel phenomenon in the infrared scanning image are analyzed. The detection and compensation method of the flickering pixel based on the time series multi-frame maximum projection is designed. Considering that the flickering pixels still retain a part of the information acquisition ability, the one-dimensional median filter is used to suppress the background for the position w here flickering pixels exist. Traditional methods of target detection are carried out for the image after flickering pixels compensated. Experiment results show that after background suppression, the target average signal to clutter ratio in the flickering pixel location can reach96% of the normal position, and the target information is w ell preserved. The traditional method of target detection is no longer interfered by flickering noise.

Abstract:Image processing makes super-resolution infrared image reconstruction effectively improve infrared images resolution, w hich breaks through hardw are performance limits. Based on deep learning, super-resolution method is applied to infrared image, w hich enables the super-resolution reconstruction of single-frame infrared image. Thus, better evaluation results are acquired. Derived from adversarial thoughts, adding a loss function based on discriminant netw ork can improve magnification, w hich can access to better high-frequency details of the restoration and can sharpen image edge and avoid blurred super-resolution infrared images.

Abstract:To solve the problems of narrow coverage spectrum and difficulty of generation of near-infrared band laser, an experiment al system is developed for multi-w avelength picosecond laser based on stimulated Raman scattering effects. Generation of visible and near-infrared band multi-w avelength picosecond laser is facilitated w ith methods such as focusing laser beam pump and laser pump energy optimizing and coupling, using 1 k Hz repetition frequency and 532 nm w avelength picosecond laser source pump KGd ( WO4) 2 crystal. The seventh order stokes and sixth order anti-stokes lasers generated cover the spectrum of 415 ~ 800 nm w ith an output Raman laser pow er of 1. 76 W. Results of the study can be used in the research and development of new picosecond laser sources.

Abstract:In order to simulate the spectral distribution difference betw een the target and the interference in real scene, a zoom optical engine w ith tw o channels and the same caliber has been designed based on dual digital micro-mirror device ( DM D) , it includes projection optical system and tw o illumination optical systems. The optical engine directly illuminates tw o DM D target surfaces respectively w ith long-w ave infrared ( LWIR) and mid-w ave infrared ( M WIR) Kohler telecentric beam. It uses spatial stereoscopic layout to get avoid of interference betw een different optical paths. The design result show s that the illuminance uniformity of illumination optical system is better than 94%. The modulation transfer function ( M TF) values of zoom projection optical system are better than 0. 4 and better than 0. 7 at 101 p/mm respectively in bands of LWIR ( 8 ~ 12 μm) and M WIR ( 3. 7 ~ 4. 8 μm) . And the distortion is better than 0. 5%, w hich meet the requirements.

Abstract:Cloud top height could be retrieved by polarized information. In order to reduce the uncertainty of retrieval results caused by the variability of cloud and surface polarized properties, the multi-angle polarized information of 490 nm band and 865 nm band w as used to retrieve cirrus cloud top height.Atmospheric top polarized information and the differences of atmospheric top polarized information betw een 490 nm band and 865 nm band w as theoretically analyzed, w hich show ed that it w as feasible to retrieve cirrus cloud top height using polarized reflectance difference betw een 490 nm band and 865 nm band. Cirrus cloud w as assumed as General Habit M ixture ( GHM) model, the polarized reflectance difference w as evaluated by the vector radiative transfer model based on adding-doubling method, and the sensitivity of polarized reflectance to cirrus cloud effective radius, optical thickness and cloud top pressure w ere evaluated. The results show that w hen the cirrus cloud optical thickness is greater than 3, the polarized reflectance difference is not sensitive to the change of effective particle radius and optical thickness, and is sensitive to the change of cloud top pressure. The polarized reflectance difference look-up table w as constructed by choosing appropriate parameters according to sensitivity analysis, and retrieved cirrus cloud top heights using look-up table method base on POLDER3 data. The retrieval results w ere compared w ith POLDER3 product and M ODIS product. The results indicate that compared w ith the official POLDER3 algorithm, the polarized reflectance difference look-up table method could applied to a w ider scattering angle range, and had a better consistency w ith M ODIS product.

Abstract:In this paper, basing on the radial-line w aveguide combining technology, the W-band pow er amplifier is designed. The design of amplifier uses 4-w ay Ga N M M IC combination. The output pow er is 3. 7 W at 90 GHz and the combining efficiency is 94. 3%. This structure has a good engineering application value.

Abstract:Remote sensing-based estimation of soil moisture is crucial in many aspects including basinscale w ater resource management, irrigation scheduling, regional scale drought monitoring and crop yield forecasting. In this study, w e evaluate the potential of visible/thermal-infrared remote sensing in soil moisture estimation, by assessing the TVDI-based method and three categories of methods based on evaporative fraction/potential evaporation ratio ( EFM1, EFM2 and EFM3) . In combination w ith ASTER data set, soil moisture in middle reach of the Heihe River Basin is predicted by the above-mentioned four methods and validated by the ground-based measurements from eco-hydrological w ireless sensor netw ork and hydro meteorological observation netw ork in the middle reach of Heihe river basin.Results indicate that uncertainties arise from the empiricism of the TVDI-based method in the process ofdetermining dry and w et edges. On the other hand, the evaporation fraction/potential evaporation ratio methods can to some degree reduce the uncertainties, and among the three methods, EFM1 and EFM3 outperform EFM2. In addition, the thermal-infrared based methods require accurate soil parameters to reproduce the variation of soil moisture.

Abstract:In this paper, the disastrous influence to the landing aircraft of low-level w ind shear and present study to the low-level w ind shear field observation have been explained briefly and the method of retrieving headw ind profiles from step w ise PPI scans in detail. The data w ith multi-mode analyzed in this paper are based on short range CDL configured at BCIA ( Beijing Capital International Airport) from December 2015 to M arch 2016. The reliability of algorithms have been proved by w ind shear reports from the crew and the airport terminal control office. CDL has been proved to be an effective tool to capture the low-level w ind shear events under clear conditions.

Abstract:In this paper, normalized difference cloud moving index ( NDCM I) is put forw ard by analyzing the remote sensing data every 15 minutes. By applying NDCM I, the detection of low cloud, thin cloud and the edge of moving cloud can be enhanced. We proposed a dynamic threshold method w ith NDCM I for preliminary cloud detection, and then through the preliminary results, w e proposed a novel cloud detection method based on back propagation neural netw ork ( BP-NN) . The experimental results show that the proposed method can eliminate the subjectivity in threshold selection, and can achieve better cloud detection results for remote sensing image in complex situations.

Abstract:Although the similarities betw een radar imaging and diffraction tomography have been recognized, the connection betw een them is often surprising to practitioners in these fields. The main goal of this paper is to consider together tw o imaging techniques and clarify the similarities and differences that exist betw een them. First, Tw o imaging techniques are derived from Stratton-Chu formula of the inverse scattering problem, w hich allow s a clear understanding of the relationship betw een the imaging equations and the imaging targets. The targets reconstructed by radar imaging are the perfectly conducting bodies, the targets reconstructed by diffraction tomography are the dielectric bodies. Then, this derivation brings out the similarities of the solution to the unlinear imaging problem w hich are hidden by the linear approximation method, radar imaging from high frequency asymptotic approximation, diffraction tomography from w eak scattering approximation. Finally, Tw o imaging techniques are discribed as Fourier imaging, w hich is used to identify the unknow n image profile as the inverse Fourier Transform of some composite function constructed from the received data signals.

Abstract:Using formation netw orking of micro-satellites to observe the earth and miniaturizing microw ave devices has been one of the development trends of space remote sensing. Based on atmospheric microw ave sounder for micro-satellites, tw o high-performance terahertz w aveguide diplexers w ere designed. With mode-matching method, the discontinuity element of diplexer w as analyzed and the parameters of diplexer w ere optimized. In order to improve out-band rejection of 89 GHz filter, different w idths of resonant cavity w as adopted. The simulation results indicated that tw o diplexers had good performance in insertion loss, out-band rejection, return loss, etc. It is proved that mode-matching method is effective in designing terahertz devices.

Abstract:The paper briefly introduces several main temperature measurement methods of aero-engine turbine blades, and summarizes the temperature measurement principle, technical characteristics and current research status of thermocouple, crystal, temperature sensitive paint, fluorescence, optical fiber, infrared radiation and multispectral. Finally, the future development trend of turbine blade temperature measurement is prospected.