The physical trend of group-I/tellurides is unexpected and contrary to the conventional wisdom. The present firstprinciples calculations give fundamental insights into the extent to which group-Ⅱ telluride compounds ...The physical trend of group-I/tellurides is unexpected and contrary to the conventional wisdom. The present firstprinciples calculations give fundamental insights into the extent to which group-Ⅱ telluride compounds present special properties upon mixing the d valence character. Our results provide explanations for the unexpected experimental observations based on the abnormal binding ordering of metal d electrons and their strong perturbation to the band edge states. The insights into the binary tellurides are useful for the study and control of the structural and chemical perturbation in their ternary alloys and heterostructures.展开更多
The Infrared Hyperspectral Atmospheric SounderⅡ(HIRAS-Ⅱ)is the key equipment on FengYun-3E(FY-3E)satellite,which can realize vertical atmospheric detection,featuring hyper spectral,high sensitivity and high precisio...The Infrared Hyperspectral Atmospheric SounderⅡ(HIRAS-Ⅱ)is the key equipment on FengYun-3E(FY-3E)satellite,which can realize vertical atmospheric detection,featuring hyper spectral,high sensitivity and high precision.To ensure its accuracy of detection,it is necessary to correlate their thermal models to in-orbit da⁃ta.In this work,an investigation of intelligent correlation method named Intelligent Correlation Platform for Ther⁃mal Model(ICP-TM)was established,the advanced Kriging surrogate model and efficient adaptive region opti⁃mization algorithm were introduced.After the correlation with this method for FY-3E/HIRAS-Ⅱ,the results indi⁃cate that compared with the data in orbit,the error of the thermal model has decreased from 5 K to within±1 K in cold case(10℃).Then,the correlated model is validated in hot case(20℃),and the correlated model exhibits good universality.This correlation precision is also much superiors to the general ones like 3 K in other similar lit⁃erature.Furthermore,the process is finished in 8 days using ICP-TM,the efficiency is much better than 3 months based on manual.The results show that the proposed approach significantly enhances the accuracy and efficiency of thermal model,this contributes to the precise thermal control of subsequent infrared optical payloads.展开更多
The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave...The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation.However,there are strong non-uniformity and blind pixels in the short-wave infrared image,which makes the image distorted and leads to the decrease of spot centroid positioning accuracy.Therefore,the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance.A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two,further model-based localization error simulations are performed,and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector.The experimental results show that the non-uniformity of the corrected image is reduced from 7%to 0.6%,the blind pixels rejection rate reaches 100%,the frame rate can be up to 2000 Hz,and the spot centroid localization accuracy is as high as 0.1 pixel point,which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.展开更多
The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively...The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively analysed by the interferometer optical range difference velocity stability.The article proposes a more comprehen⁃sive method of analysing the optical range difference velocity uniformity for the reliability of the interferometer ki⁃nematic mechanism under the influence of on-orbit microvibration in the process of space spectroscopy detection.The method incorporates the structural response of the interferometer caused by external excitation into the stabili⁃ty analysis as one of the influencing factors,so as to reflect the reliability of the interferometer in orbit more realis⁃tically,and judge the microvibration criticality that the interferometer can withstand more accurately.At the same time,an optical surface model of the interferometer is established to further theoretically characterise the effect of microvibration on the homogeneity of the interferometric mechanism.The method discussed in the article pro⁃vides a way of thinking for the judgement of the reliability of the mechanism movement under the external excita⁃tion perturbation as well as the research on the optimisation of the mechanism control.展开更多
In this paper,we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures,extend its design,and characterize...In this paper,we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures,extend its design,and characterize the parameters of the model in detail.By employing this model,we conducted computations to characterize the response wavelength and bandwidth of variously sized metamaterial absorbers.A comparative analysis with Finite Difference Time Domain(FDTD)simulations demonstrated a remarkable level of consistency in the results.The designed absorbers were fabricated using micro-nano fabrication processes,and were experimentally tested to demonstrate absorption rates exceeding 90%at a wavelength of 9.28μm.The predicted results are then compared with test results.The comparison reveals good consistency in two aspects of the resonance responses,thereby confirming the rationality and accuracy of this model.展开更多
In order to meet the urgent need of infrared search and track applications for accurate identification and positioning of infrared guidance aircraft,an active-detection mid-wave infrared search and track system(ADMWIR...In order to meet the urgent need of infrared search and track applications for accurate identification and positioning of infrared guidance aircraft,an active-detection mid-wave infrared search and track system(ADMWIRSTS)based on"cat-eye effect"was developed.The ADMWIRSTS mainly consists of both a light beam control subsystem and an infrared search and track subsystem.The light beam control subsystem uses an integrated opto-mechanical two-dimensional pointing mirror to realize the control function of the azimuth and pitch directions of the system,which can cover the whole airspace range of 360°×90°.The infrared search and track subsystem uses two mid-wave infrared cooled 640×512 focal plane detectors for co-aperture beam expanding,infrared and illumination laser beam combining,infrared search,and two-stage track opto-mechanical design.In this work,the system integration design and structural finite-element analysis were conducted,the search imaging and two-stage track imaging for external scenes were performed,and the active-detection technologies were experimentally verified in the laboratory.The experimental investigation results show that the system can realize the infrared search and track imaging,and the accurate identification and positioning of the mid-wave infrared guidance,or infrared detection system through the echo of the illumination laser.The aforementioned work has important technical significance and practical application value for the development of compactly-integrated high-precision infrared search and track,and laser suppression system,and has broad application prospects in the protection of equipment,assets and infrastructures.展开更多
Helium sorption cooler technology is a key means to realize highly reliable low-vibration very lowtemperature environments,which have important applications in fields such as quantum computing and space exploration.Th...Helium sorption cooler technology is a key means to realize highly reliable low-vibration very lowtemperature environments,which have important applications in fields such as quantum computing and space exploration.The laboratory designed a superfluid suppression small hole and a multi-ribbed condenser,developed a reliable-performance helium sorption cooler(HSC),and conducted experimental studies.Experimental results show that the prototype can achieve the lowest cooling temperature of 873 mK without load by filling 6MPa helium at room temperature.The low-temperature hold time is 26 h,and the temperature fluctuation is within 0.8 mK.The cooling power of the helium sorption cooler is 1 mW@0.98 K@3.5 h.Experimental results indicate that when the charging pressure is reduced to 4MPa,theminimum temperature decreases to 836mK,and the hold time shortens to 16 h.When the pre-cooling temperature increases from 3.9 to 4.9 K,the hold time is reduced to 3 h.展开更多
We report the bifurcation of bound states in the continuum(BICs) in a dissipative cavity magnonic system, where a BIC splits into a pair of BICs. We theoretically analyze BICs in a dissipative cavity magnonic system a...We report the bifurcation of bound states in the continuum(BICs) in a dissipative cavity magnonic system, where a BIC splits into a pair of BICs. We theoretically analyze BICs in a dissipative cavity magnonic system and derive the critical condition for BICs bifurcation. Based on the theoretical results, we experimentally tune the dissipative photon–magnon coupling strength and demonstrate precise control over the detuning and number of BICs. When the dissipative coupling strength reaches a critical value, we observe the bifurcation of BICs, which is consistent with the theoretical prediction. Our systematic investigation of the evolution of BICs concerning the dissipative coupling strength and the discovery of the BIC bifurcation may enhance the sensitivity of BICs to external perturbations, potentially enabling applications in ultrasensitive detection.展开更多
The China Space Station Telescope(CSST)is a 2 m three-mirror anastigmat equipped with a Fast Steering Mirror(FSM),which is part of its precision image stabilization system.The FSM is used to compensate for residuals f...The China Space Station Telescope(CSST)is a 2 m three-mirror anastigmat equipped with a Fast Steering Mirror(FSM),which is part of its precision image stabilization system.The FSM is used to compensate for residuals from the previous stage of the image stabilization system.However,a new type of image stabilization residual caused by image rotation and projection distortion is introduced when the FSM performs tip-tilt adjustments,reducing both the image stabilization accuracy and the absolute pointing accuracy of the CSST.In this paper,we propose a scheme to compute the image stabilization residuals across the full field of view(FOV)by using a reference star as the target for stabilization control,which can be utilized for subsequent image position correction.To achieve this,we developed a linear optical model for image point displacement by simplifying an existing image point displacement model and incorporating more readily available parameters.The computational accuracy of the new model is equivalent to that of the original,with computational differences of less than 0.03μm.Based on this linear model,we established a calculation model for image stabilization residuals,including those due to image rotation and projection distortion caused by FSM tip-tilt adjustments.This model provides a theoretical foundation for quantifying such residuals during the image stabilization process.Finally,the results of testing using this scheme are provided.Experimental results demonstrate that within the observation FOV of the CSST,when the FSM tilts by(1″,1″),the maximum absolute value of the image stabilization residuals accounts for 20%of the total image stabilization accuracy requirement.This finding underscores the necessity of computing and correcting these residuals to meet performance requirements.展开更多
Over the past few decades,angle-resolved photoemission spectroscopy(ARPES)has been one of the important tools to study electronic structure of crystals.In recent years,the spatial resolution of around 150 nm has been ...Over the past few decades,angle-resolved photoemission spectroscopy(ARPES)has been one of the important tools to study electronic structure of crystals.In recent years,the spatial resolution of around 150 nm has been reached through tight focusing of the light spot(nano-ARPES).At present,the lower limit of the spot size of the light on the sample has been reached.Another way to further improve the spatial resolution is through using apertures to only let electrons from a small area of the sample pass.With both back-focal plane and image apertures,the size of the selected area can be as small as 20 nm.Yet,without aberration correction,the maximum opening angle at the sample for 20 nm spatial resolution is usually smaller than 3°,making this method not suitable for nano-ARPES.As shown in this paper,a conventional aberration corrector,which corrects chromatic and third-order spherical aberrations,is not enough either.Only when the fifth-order spherical aberration is also corrected,the opening angle at the sample is large enough for nano-ARPES.In this paper,the design of a time-of-fight PEEM/ARPES/nano-ARPES instrument,which is currently under development at the Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area,is presented.The main point of innovation is a fiveelectrode electron mirror corrector,which is used to correct simultaneously chromatic,third-order and fifth-order spherical aberrations,resulting in 1 nm spatial resolution with~230 mrad aperture angle in PEEM mode.This makes feasible the method of using apertures to improve the spatial resolution of the nano-ARPES mode.A new design of the magnetic prism array(MPA)is also presented,which preserves the rotational symmetry better than the existing designs.展开更多
Airborne hyperspectral imaging spectrometers have been used for Earth observation over the past four decades.Despite the high sensitivity of push-broom hyperspectral imagers,they experience limited swath and wavelengt...Airborne hyperspectral imaging spectrometers have been used for Earth observation over the past four decades.Despite the high sensitivity of push-broom hyperspectral imagers,they experience limited swath and wavelength coverage.In this study,we report the development of a push-broom airborne multimodular imaging spectrometer(AMMIS)that spans ultraviolet(UV),visible near-infrared(VNIR),shortwave infrared(SWIR),and thermal infrared(TIR)wavelengths.As an integral part of China's HighResolution Earth Observation Program,AMMIS is intended for civilian applications and for validating key technologies for future spaceborne hyperspectral payloads.It has been mounted on aircraft platforms such as Y-5,Y-12,and XZ-60.Since 2016,AMMIS has been used to perform more than 30 flight campaigns and gather more than 200 TB of hyperspectral data.This study describes the system design,calibration techniques,performance tests,flight campaigns,and applications of the AMMIS.The system integrates UV,VNIR,SWIR,and TIR modules,which can be operated in combination or individually based on the application requirements.Each module includes three spectrometers,utilizing field-of-view(FOV)stitching technology to achieve a 40°FOV,thereby enhancing operational efficiency.We designed advanced optical systems for all modules,particularly for the TIR module,and employed cryogenic optical technology to maintain optical system stability at 100 K.Both laboratory and in-flight calibrations were conducted to improve preprocessing accuracy and produce high-quality hyperspectral data.The AMMIS features more than 1400 spectral bands,with spectral sampling intervals of 0.1 nm for UV,2.4 nm for VNIR,3 nm for SWIR,and 32 nm for TIR.In addition,the instantaneous fields of view(IFoVs)for the four modules were 0.5,0.25,0.5,and 1 mrad,respectively,with the VNIR module achieving an IFoV of 0.125 mrad in the high-spatial-resolution mode.This study reports on land-cover surveys,pollution gas detection,mineral exploration,coastal water detection,and plant investigations conducted using AMMIS,highlighting its excellent performance.Furthermore,we present three hyperspectral datasets with diverse scene distributions and categories suitable for developing artificial intelligence algorithms.This study paves the way for next-generation airborne and spaceborne hyperspectral payloads and serves as a valuable reference for hyperspectral sensor designers and data users.展开更多
Piezoelectric nanogenerators(PENGs) are evolving as next-generation energy harvesters due to their self-powered sensing,multi-stimuli-responsiveness,and wearable electronics.Here,we present a flexible PENG utilizing e...Piezoelectric nanogenerators(PENGs) are evolving as next-generation energy harvesters due to their self-powered sensing,multi-stimuli-responsiveness,and wearable electronics.Here,we present a flexible PENG utilizing electro spun poly(vinylidene fluoride trifluoroethylene)(P(VDF-TrFE)) nanofibers.By optimizing the rotational speeds during the electrospinning process,we have achieved nanofibers with a highly aligned structure and uniform polarβ-phase,an enhancement of piezoelectric response,particularly in terms of sensitivity and power generation.The longitudinal piezoelectric coefficient(d_(33)) reaches-21.6 pC·N^(-1).The transverse piezoelectric measurement yields an output of 26 V and 38.6 nA.The device exhibits an ultra-high sensitivity of 5.76 V·kPa^(-1),surpassing previously reported values by orders of magnitude.The PENG is successfully employed for Braille recognition and the precise manipulation of a robotic hand,indicating its efficacy for tactile interaction systems.This study presents a novel approach to facilitating intelligent human-machine interaction by exploiting the unique properties of organic piezoelectric materials.展开更多
The infrared band contains rich opportunities for astronomical research,but due to the limitations of infrared technology,the development of infrared astronomy in China has been far from satisfactory for a long time,e...The infrared band contains rich opportunities for astronomical research,but due to the limitations of infrared technology,the development of infrared astronomy in China has been far from satisfactory for a long time,especially for solar observation.“Accurate Infrared Magnetic field Measurements of the Sun”project(AIMS)is a National Major Scientific Research Instrument Development Project(recommended by the Ministries)supported by the National Natural Science Foundation of China.It is aimed at improving the accuracy of magnetic field measurement by an order of magnitude,by measuring the“Zeeman splitting”directly.In addition,as AIMS is also the first equipment specifically designed for mid-to far-infrared solar observation in the world,we also hope to utilize AIMS to explore potential new scientific research opportunities in the vast infrared region.This article will briefly introduce the scientific objectives,the telescope,the scientific post-focus instruments,and finally summarize the commissioning observations of AIMS.展开更多
Sea ice thickness is one of the most important input parameters in the studies on sea ice disaster prevention and mitigation. It is also the most important content in remote sensing monitoring of sea ice. In this stud...Sea ice thickness is one of the most important input parameters in the studies on sea ice disaster prevention and mitigation. It is also the most important content in remote sensing monitoring of sea ice. In this study, a practical model of sea ice thickness(PMSIT) was proposed based on the Moderate Resolution Imaging Spectroradiometer(MODIS) data. In the proposed model, the MODIS data of the first band were used to estimate sea ice thickness and the difference between the second-band reflectance and the fifth-band reflectance in the MODIS data was calculated to obtain the difference attenuation index(DAI) of each pixel. The obtained DAI was used to estimate the integrated attenuation coefficient of the first band of the MODIS at the pixel level. Then the model was used to estimate sea ice thickness in the Bohai Sea with the MODIS data and then validated with the actual sea ice survey data. The validation results showed that the proposed model and corresponding parameterization scheme could largely avoid the estimation error of sea ice thickness caused by the spatial and temporal heterogeneity of sea ice extinction and allowed the error of 18.7% compared with the measured sea ice thickness.展开更多
We perform a theoretical study on a low dark current InGaAs/GaAs very-long-wavelength （〉 12 μm） quantum well infrared photodetector （VLW-QWIP）, based on a double barrier resonant tunnelling structure （DBRTS）. ...We perform a theoretical study on a low dark current InGaAs/GaAs very-long-wavelength （〉 12 μm） quantum well infrared photodetector （VLW-QWIP）, based on a double barrier resonant tunnelling structure （DBRTS）. The ground tunnelling state of the central quantum well （QW） of the DBRTS can resonate with the first excited bound state of the doped InGaAs QW by adjusting the structure parameters of the DBRTS. Investigation of the carrier transport performance of this device is carried out based on quantum wave transport theory. It has been shown that the dark current in this device can be significantly reduced by two orders compared to conventional InGaAs/GaAs VLW-QWIPs, while the photocurrent is almost the same as those in conventional VLW-QWIPs. This DBRTS integrated VLW-QWIP structure may stimulate the experimental investigation for VLW-QWIPs at high operation temperatures.展开更多
The surface roughness characteristics （e.g., height and slope） of sea ice are critical for determining the parameters of an electromagnetic scattering, a surface emission and a surface drag coefficients. It is also ...The surface roughness characteristics （e.g., height and slope） of sea ice are critical for determining the parameters of an electromagnetic scattering, a surface emission and a surface drag coefficients. It is also important in identifying various ice types, retrieval ice thickness, surface temperature and drag coefficients from remote sensing data. The point clouds （a set of points which are usually defined by X, Y, and Z coordinates that represents the external surface of an object on earth） of land fast ice in five in situ sites in the eastern coast Bohai Sea were measured using a laser scanner-Trimble GX during 2011-2012 winter season. Two hundred and fifty profiles selected from the point clouds of different samples have been used to calcu- late the height root mean square, height skewness, height kurtosis, slope root mean square, slope skewness and slope kurtosis of them. The root mean square of the height, the root mean square of the slope and the correlation length are about 0.090, 0.075 and 11.74 m, respectively. The heights of 150 profiles in three sites manifest the Gaussian distribution and the slopes of total 250 profiles distributed exponentially. In addition, the fractal dimension and power spectral density profiles were calculated. The results show that the fractal dimension of land fast ice in the Bohai Sea is about 1.132. The power spectral densities of 250 profiles can be expressed through an exponential autocorrelation function.展开更多
InAsSb epilayers with a cutoff wavelength of 4.8 μm have been successfully grown on InAs substrates by one-step liquid phase epitaxy （LPE） technology. The epilayers were characterized by X-ray diffraction （XRD）, ...InAsSb epilayers with a cutoff wavelength of 4.8 μm have been successfully grown on InAs substrates by one-step liquid phase epitaxy （LPE） technology. The epilayers were characterized by X-ray diffraction （XRD）, Fourier transform infrared （PTIR） transmittance measurements and scanning electron microscopy （SEM）. The influence of different growth conditions on the optical and structural properties of the materials was studied. The results revealed that the good crystalline quality, mirror smooth surface and flat interface of InAsSb epilayers were achieved. They benefited from optimized growth conditions, i.e., sufficient homogeneity of the growth melt and a very slow cooling rate.展开更多
Diffusion bonding is a near net shape forming process that can join dissimilar materials through atomic diffusion under a high pressure at a high temperature.Titanium alloy TC4（Ti-6 Al-4 V）and 4 J29 Kovar alloy（Fe-...Diffusion bonding is a near net shape forming process that can join dissimilar materials through atomic diffusion under a high pressure at a high temperature.Titanium alloy TC4（Ti-6 Al-4 V）and 4 J29 Kovar alloy（Fe-29 Ni-17 Co）were diffusely bonded by a vacuum hot-press sintering process in the temperature range of 700-850°C and bonding time of 120 min,under a pressure of 34.66 MPa.Interfacial microstructures and intermetallic compounds of the diffusion-bonded joints were characterized by optical microscopy,scanning electron microscopy,X-ray diffraction（XRD）and energy dispersive spectroscopy（EDS）.The elemental diffusion across the interface was revealed by electron probe microanalysis.Mechanical properties of joints were investigated by micro Vickers hardness and tensile strength.Results of EDS and XRD indicated that（Fe,Co,Ni）-Ti,TiNi,Ti_2Ni,TiNi_2,Fe_2 Ti,Ti_（17） Mn_3 and Al_6 Ti_（19） were formed at the interface.When the bonding temperature was raised from 700 to 850°C,the voids of interface were reduced and intermetallic layers were widened.Maximum tensile strength of joints at 53.5 MPa was recorded by the sintering process at 850°C for 120 min.Fracture surface of the joint indicated brittle nature,and failure took place through interface of intermetallic compounds.Based on the mechanical properties and microstructure of the diffusion-bonded joints,diffusion mechanisms between Ti-6 Al-4 Vtitanium and Fe-29 Ni-17 Co Kovar alloys were analyzed in terms of elemental diffusion,nucleation and growth of grains,plastic deformation and formation of intermetallic compounds near the interface.展开更多
Aiming at the problems in a linear frequency modulation continuous wave(LFMCW)ranging lidar system,such as low signal-to-noise in echo beat frequency and difficult extraction of the signal frequency,a method with high...Aiming at the problems in a linear frequency modulation continuous wave(LFMCW)ranging lidar system,such as low signal-to-noise in echo beat frequency and difficult extraction of the signal frequency,a method with high-speed and high accuracy based on field programmable gate array(FPGA)is proposed.Firstly,the laser echo beat signal is sampled by high-speed analog to digital converter(ADC)and then processed in FPGA for data preprocessing.After the signal is processed by the 8192-point FPGA will obtain the frequency spectrum and then apply the frequency spectrum to data processing and adaptive noise signal peak detection.These two steps realize the real-time and accurate extraction process of the target echo beat signal frequency.Finally,the spectrum data is transmitted to the host computer and processed through the external data acquisition board for real-time spectrum display.Experimental results show that data preprocessing and spectrum data processing can effectively suppress DC bias and system modulation noise.Adaptive noise peak detection can accurately divide the threshold contour according to the dynamic noise of the system and realize the detection of target signal peak.When the sampling clock of the system is 100 MHz,the time needed for each calculation of the spectrum is 81.92μs,and the refresh rate of the spectrum reaches 12.2 kHz,which meets the real-time requirements of the system.展开更多
Chang'E-1,the orbiter circling the moon 200km above the moon surface,is the first Chinese Lunar exploration satellite.The satellite was successfully launched on 24th October 2007.There are 8 kinds of scientific pa...Chang'E-1,the orbiter circling the moon 200km above the moon surface,is the first Chinese Lunar exploration satellite.The satellite was successfully launched on 24th October 2007.There are 8 kinds of scientific payloads onboard,including the stereo camera,the laser altimeter,the Sagnac-based interferometer image spectrometer,the Gamma ray spectrometer,the X-ray spectrom-eter,the microwave radiometer,the high energy particle detector,the solar wind plasma detector and a supporting payload data management system.Chang'E-1 opened her eyes to look at the moon and took the first batch of lunar pictures after her stereo camera was switched on in 20th November 2007.Henceforth all the instruments are successfully switched on one by one.After a period of parameter adjustment and initial check out,all scientific instruments are now in their normal operating phase.In this paper,the payloads and the initial observation results are introduced.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10847111 and 61006091)the Startup Project for Ph. D. of Guangdong University of Technology (Grant No. 083034)the Fundamental Research Funds for the Central Universities of South China University of Technology (Grant No. 2009ZM0022)
文摘The physical trend of group-I/tellurides is unexpected and contrary to the conventional wisdom. The present firstprinciples calculations give fundamental insights into the extent to which group-Ⅱ telluride compounds present special properties upon mixing the d valence character. Our results provide explanations for the unexpected experimental observations based on the abnormal binding ordering of metal d electrons and their strong perturbation to the band edge states. The insights into the binary tellurides are useful for the study and control of the structural and chemical perturbation in their ternary alloys and heterostructures.
基金Supported by the National Key Research and Development Program of China(2022YFB3904803)。
文摘The Infrared Hyperspectral Atmospheric SounderⅡ(HIRAS-Ⅱ)is the key equipment on FengYun-3E(FY-3E)satellite,which can realize vertical atmospheric detection,featuring hyper spectral,high sensitivity and high precision.To ensure its accuracy of detection,it is necessary to correlate their thermal models to in-orbit da⁃ta.In this work,an investigation of intelligent correlation method named Intelligent Correlation Platform for Ther⁃mal Model(ICP-TM)was established,the advanced Kriging surrogate model and efficient adaptive region opti⁃mization algorithm were introduced.After the correlation with this method for FY-3E/HIRAS-Ⅱ,the results indi⁃cate that compared with the data in orbit,the error of the thermal model has decreased from 5 K to within±1 K in cold case(10℃).Then,the correlated model is validated in hot case(20℃),and the correlated model exhibits good universality.This correlation precision is also much superiors to the general ones like 3 K in other similar lit⁃erature.Furthermore,the process is finished in 8 days using ICP-TM,the efficiency is much better than 3 months based on manual.The results show that the proposed approach significantly enhances the accuracy and efficiency of thermal model,this contributes to the precise thermal control of subsequent infrared optical payloads.
基金Supported by the Short-wave Infrared Camera Systems(B025F40622024)。
文摘The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation.However,there are strong non-uniformity and blind pixels in the short-wave infrared image,which makes the image distorted and leads to the decrease of spot centroid positioning accuracy.Therefore,the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance.A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two,further model-based localization error simulations are performed,and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector.The experimental results show that the non-uniformity of the corrected image is reduced from 7%to 0.6%,the blind pixels rejection rate reaches 100%,the frame rate can be up to 2000 Hz,and the spot centroid localization accuracy is as high as 0.1 pixel point,which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.
文摘The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively analysed by the interferometer optical range difference velocity stability.The article proposes a more comprehen⁃sive method of analysing the optical range difference velocity uniformity for the reliability of the interferometer ki⁃nematic mechanism under the influence of on-orbit microvibration in the process of space spectroscopy detection.The method incorporates the structural response of the interferometer caused by external excitation into the stabili⁃ty analysis as one of the influencing factors,so as to reflect the reliability of the interferometer in orbit more realis⁃tically,and judge the microvibration criticality that the interferometer can withstand more accurately.At the same time,an optical surface model of the interferometer is established to further theoretically characterise the effect of microvibration on the homogeneity of the interferometric mechanism.The method discussed in the article pro⁃vides a way of thinking for the judgement of the reliability of the mechanism movement under the external excita⁃tion perturbation as well as the research on the optimisation of the mechanism control.
基金Supported by the National Natural Science Foundation of China(62174092)the Open Fund of State Key Laboratory of Infrared Physics(SITP-NLIST-ZD-2023-04)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0580000)。
文摘In this paper,we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures,extend its design,and characterize the parameters of the model in detail.By employing this model,we conducted computations to characterize the response wavelength and bandwidth of variously sized metamaterial absorbers.A comparative analysis with Finite Difference Time Domain(FDTD)simulations demonstrated a remarkable level of consistency in the results.The designed absorbers were fabricated using micro-nano fabrication processes,and were experimentally tested to demonstrate absorption rates exceeding 90%at a wavelength of 9.28μm.The predicted results are then compared with test results.The comparison reveals good consistency in two aspects of the resonance responses,thereby confirming the rationality and accuracy of this model.
基金Supported by the Fundamental Scientific Research Plan of China(JCKY2021130B033)。
文摘In order to meet the urgent need of infrared search and track applications for accurate identification and positioning of infrared guidance aircraft,an active-detection mid-wave infrared search and track system(ADMWIRSTS)based on"cat-eye effect"was developed.The ADMWIRSTS mainly consists of both a light beam control subsystem and an infrared search and track subsystem.The light beam control subsystem uses an integrated opto-mechanical two-dimensional pointing mirror to realize the control function of the azimuth and pitch directions of the system,which can cover the whole airspace range of 360°×90°.The infrared search and track subsystem uses two mid-wave infrared cooled 640×512 focal plane detectors for co-aperture beam expanding,infrared and illumination laser beam combining,infrared search,and two-stage track opto-mechanical design.In this work,the system integration design and structural finite-element analysis were conducted,the search imaging and two-stage track imaging for external scenes were performed,and the active-detection technologies were experimentally verified in the laboratory.The experimental investigation results show that the system can realize the infrared search and track imaging,and the accurate identification and positioning of the mid-wave infrared guidance,or infrared detection system through the echo of the illumination laser.The aforementioned work has important technical significance and practical application value for the development of compactly-integrated high-precision infrared search and track,and laser suppression system,and has broad application prospects in the protection of equipment,assets and infrastructures.
基金supported by the Hundred Talents Programof the Chinese Academy of Sciences,the Pre-Research Project JZX7Y20220414101801the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB35000000)the National Natural Science Foundation Projects(No.51806231).
文摘Helium sorption cooler technology is a key means to realize highly reliable low-vibration very lowtemperature environments,which have important applications in fields such as quantum computing and space exploration.The laboratory designed a superfluid suppression small hole and a multi-ribbed condenser,developed a reliable-performance helium sorption cooler(HSC),and conducted experimental studies.Experimental results show that the prototype can achieve the lowest cooling temperature of 873 mK without load by filling 6MPa helium at room temperature.The low-temperature hold time is 26 h,and the temperature fluctuation is within 0.8 mK.The cooling power of the helium sorption cooler is 1 mW@0.98 K@3.5 h.Experimental results indicate that when the charging pressure is reduced to 4MPa,theminimum temperature decreases to 836mK,and the hold time shortens to 16 h.When the pre-cooling temperature increases from 3.9 to 4.9 K,the hold time is reduced to 3 h.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2023YFA1406604)the National Natural Science Foundation of China (Grant Nos. 12274260, 12204306, 12122413, and 12474120)+1 种基金the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2024YQ001)the Qilu Young Scholar Programs of Shandong University。
文摘We report the bifurcation of bound states in the continuum(BICs) in a dissipative cavity magnonic system, where a BIC splits into a pair of BICs. We theoretically analyze BICs in a dissipative cavity magnonic system and derive the critical condition for BICs bifurcation. Based on the theoretical results, we experimentally tune the dissipative photon–magnon coupling strength and demonstrate precise control over the detuning and number of BICs. When the dissipative coupling strength reaches a critical value, we observe the bifurcation of BICs, which is consistent with the theoretical prediction. Our systematic investigation of the evolution of BICs concerning the dissipative coupling strength and the discovery of the BIC bifurcation may enhance the sensitivity of BICs to external perturbations, potentially enabling applications in ultrasensitive detection.
基金financially supported by the National Key R&D Program of China(2022YFB3806300)。
文摘The China Space Station Telescope(CSST)is a 2 m three-mirror anastigmat equipped with a Fast Steering Mirror(FSM),which is part of its precision image stabilization system.The FSM is used to compensate for residuals from the previous stage of the image stabilization system.However,a new type of image stabilization residual caused by image rotation and projection distortion is introduced when the FSM performs tip-tilt adjustments,reducing both the image stabilization accuracy and the absolute pointing accuracy of the CSST.In this paper,we propose a scheme to compute the image stabilization residuals across the full field of view(FOV)by using a reference star as the target for stabilization control,which can be utilized for subsequent image position correction.To achieve this,we developed a linear optical model for image point displacement by simplifying an existing image point displacement model and incorporating more readily available parameters.The computational accuracy of the new model is equivalent to that of the original,with computational differences of less than 0.03μm.Based on this linear model,we established a calculation model for image stabilization residuals,including those due to image rotation and projection distortion caused by FSM tip-tilt adjustments.This model provides a theoretical foundation for quantifying such residuals during the image stabilization process.Finally,the results of testing using this scheme are provided.Experimental results demonstrate that within the observation FOV of the CSST,when the FSM tilts by(1″,1″),the maximum absolute value of the image stabilization residuals accounts for 20%of the total image stabilization accuracy requirement.This finding underscores the necessity of computing and correcting these residuals to meet performance requirements.
基金supported by Shanghai Tech University and Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area,China(Grant No.SZZX2301006)。
文摘Over the past few decades,angle-resolved photoemission spectroscopy(ARPES)has been one of the important tools to study electronic structure of crystals.In recent years,the spatial resolution of around 150 nm has been reached through tight focusing of the light spot(nano-ARPES).At present,the lower limit of the spot size of the light on the sample has been reached.Another way to further improve the spatial resolution is through using apertures to only let electrons from a small area of the sample pass.With both back-focal plane and image apertures,the size of the selected area can be as small as 20 nm.Yet,without aberration correction,the maximum opening angle at the sample for 20 nm spatial resolution is usually smaller than 3°,making this method not suitable for nano-ARPES.As shown in this paper,a conventional aberration corrector,which corrects chromatic and third-order spherical aberrations,is not enough either.Only when the fifth-order spherical aberration is also corrected,the opening angle at the sample is large enough for nano-ARPES.In this paper,the design of a time-of-fight PEEM/ARPES/nano-ARPES instrument,which is currently under development at the Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area,is presented.The main point of innovation is a fiveelectrode electron mirror corrector,which is used to correct simultaneously chromatic,third-order and fifth-order spherical aberrations,resulting in 1 nm spatial resolution with~230 mrad aperture angle in PEEM mode.This makes feasible the method of using apertures to improve the spatial resolution of the nano-ARPES mode.A new design of the magnetic prism array(MPA)is also presented,which preserves the rotational symmetry better than the existing designs.
基金supported by the Shanghai Industrial Collaborative Innovation Fund(HCXBCY-2021-001)the Academy of Finland(349229)。
文摘Airborne hyperspectral imaging spectrometers have been used for Earth observation over the past four decades.Despite the high sensitivity of push-broom hyperspectral imagers,they experience limited swath and wavelength coverage.In this study,we report the development of a push-broom airborne multimodular imaging spectrometer(AMMIS)that spans ultraviolet(UV),visible near-infrared(VNIR),shortwave infrared(SWIR),and thermal infrared(TIR)wavelengths.As an integral part of China's HighResolution Earth Observation Program,AMMIS is intended for civilian applications and for validating key technologies for future spaceborne hyperspectral payloads.It has been mounted on aircraft platforms such as Y-5,Y-12,and XZ-60.Since 2016,AMMIS has been used to perform more than 30 flight campaigns and gather more than 200 TB of hyperspectral data.This study describes the system design,calibration techniques,performance tests,flight campaigns,and applications of the AMMIS.The system integrates UV,VNIR,SWIR,and TIR modules,which can be operated in combination or individually based on the application requirements.Each module includes three spectrometers,utilizing field-of-view(FOV)stitching technology to achieve a 40°FOV,thereby enhancing operational efficiency.We designed advanced optical systems for all modules,particularly for the TIR module,and employed cryogenic optical technology to maintain optical system stability at 100 K.Both laboratory and in-flight calibrations were conducted to improve preprocessing accuracy and produce high-quality hyperspectral data.The AMMIS features more than 1400 spectral bands,with spectral sampling intervals of 0.1 nm for UV,2.4 nm for VNIR,3 nm for SWIR,and 32 nm for TIR.In addition,the instantaneous fields of view(IFoVs)for the four modules were 0.5,0.25,0.5,and 1 mrad,respectively,with the VNIR module achieving an IFoV of 0.125 mrad in the high-spatial-resolution mode.This study reports on land-cover surveys,pollution gas detection,mineral exploration,coastal water detection,and plant investigations conducted using AMMIS,highlighting its excellent performance.Furthermore,we present three hyperspectral datasets with diverse scene distributions and categories suitable for developing artificial intelligence algorithms.This study paves the way for next-generation airborne and spaceborne hyperspectral payloads and serves as a valuable reference for hyperspectral sensor designers and data users.
基金fundings of National Key Research and Development program of China (No. 2021YFA1200700)National Natural Science Foundation of China (Nos. T2222025 and 62174053)+3 种基金Natural Science Foundation of Chongqing (CSTB2024NSCQ-JQX0005)Shanghai Science and Technology Innovation Action Plan (21JC1402000 and 21520714100)the Fundamental Research Funds for the Central Universitiesthe Class Ⅲ Peak Discipline of Shanghai—Materials Science and Engineering (High-Energy Beam Intelligent Processing and Green Manufacturing)。
文摘Piezoelectric nanogenerators(PENGs) are evolving as next-generation energy harvesters due to their self-powered sensing,multi-stimuli-responsiveness,and wearable electronics.Here,we present a flexible PENG utilizing electro spun poly(vinylidene fluoride trifluoroethylene)(P(VDF-TrFE)) nanofibers.By optimizing the rotational speeds during the electrospinning process,we have achieved nanofibers with a highly aligned structure and uniform polarβ-phase,an enhancement of piezoelectric response,particularly in terms of sensitivity and power generation.The longitudinal piezoelectric coefficient(d_(33)) reaches-21.6 pC·N^(-1).The transverse piezoelectric measurement yields an output of 26 V and 38.6 nA.The device exhibits an ultra-high sensitivity of 5.76 V·kPa^(-1),surpassing previously reported values by orders of magnitude.The PENG is successfully employed for Braille recognition and the precise manipulation of a robotic hand,indicating its efficacy for tactile interaction systems.This study presents a novel approach to facilitating intelligent human-machine interaction by exploiting the unique properties of organic piezoelectric materials.
文摘The infrared band contains rich opportunities for astronomical research,but due to the limitations of infrared technology,the development of infrared astronomy in China has been far from satisfactory for a long time,especially for solar observation.“Accurate Infrared Magnetic field Measurements of the Sun”project(AIMS)is a National Major Scientific Research Instrument Development Project(recommended by the Ministries)supported by the National Natural Science Foundation of China.It is aimed at improving the accuracy of magnetic field measurement by an order of magnitude,by measuring the“Zeeman splitting”directly.In addition,as AIMS is also the first equipment specifically designed for mid-to far-infrared solar observation in the world,we also hope to utilize AIMS to explore potential new scientific research opportunities in the vast infrared region.This article will briefly introduce the scientific objectives,the telescope,the scientific post-focus instruments,and finally summarize the commissioning observations of AIMS.
基金Under the auspices of the National Natural Science Foundation of China(No.41306091)Public Science and Technology Research Funds Projects of Ocean(No.201505019-2)
文摘Sea ice thickness is one of the most important input parameters in the studies on sea ice disaster prevention and mitigation. It is also the most important content in remote sensing monitoring of sea ice. In this study, a practical model of sea ice thickness(PMSIT) was proposed based on the Moderate Resolution Imaging Spectroradiometer(MODIS) data. In the proposed model, the MODIS data of the first band were used to estimate sea ice thickness and the difference between the second-band reflectance and the fifth-band reflectance in the MODIS data was calculated to obtain the difference attenuation index(DAI) of each pixel. The obtained DAI was used to estimate the integrated attenuation coefficient of the first band of the MODIS at the pixel level. Then the model was used to estimate sea ice thickness in the Bohai Sea with the MODIS data and then validated with the actual sea ice survey data. The validation results showed that the proposed model and corresponding parameterization scheme could largely avoid the estimation error of sea ice thickness caused by the spatial and temporal heterogeneity of sea ice extinction and allowed the error of 18.7% compared with the measured sea ice thickness.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60476031 and 10474020
文摘We perform a theoretical study on a low dark current InGaAs/GaAs very-long-wavelength （〉 12 μm） quantum well infrared photodetector （VLW-QWIP）, based on a double barrier resonant tunnelling structure （DBRTS）. The ground tunnelling state of the central quantum well （QW） of the DBRTS can resonate with the first excited bound state of the doped InGaAs QW by adjusting the structure parameters of the DBRTS. Investigation of the carrier transport performance of this device is carried out based on quantum wave transport theory. It has been shown that the dark current in this device can be significantly reduced by two orders compared to conventional InGaAs/GaAs VLW-QWIPs, while the photocurrent is almost the same as those in conventional VLW-QWIPs. This DBRTS integrated VLW-QWIP structure may stimulate the experimental investigation for VLW-QWIPs at high operation temperatures.
基金The National High Technology Research and Development Program of China under contract No.2011AA100505the National Key Technology R&D Program of China under contract No.2006BAB03A03the State Key Laboratory of Earth Surface Processes and Resource Ecology,Beijing Normal University of China under contract Nos 2010-TD-02 and 2011-TDZD-050
文摘The surface roughness characteristics （e.g., height and slope） of sea ice are critical for determining the parameters of an electromagnetic scattering, a surface emission and a surface drag coefficients. It is also important in identifying various ice types, retrieval ice thickness, surface temperature and drag coefficients from remote sensing data. The point clouds （a set of points which are usually defined by X, Y, and Z coordinates that represents the external surface of an object on earth） of land fast ice in five in situ sites in the eastern coast Bohai Sea were measured using a laser scanner-Trimble GX during 2011-2012 winter season. Two hundred and fifty profiles selected from the point clouds of different samples have been used to calcu- late the height root mean square, height skewness, height kurtosis, slope root mean square, slope skewness and slope kurtosis of them. The root mean square of the height, the root mean square of the slope and the correlation length are about 0.090, 0.075 and 11.74 m, respectively. The heights of 150 profiles in three sites manifest the Gaussian distribution and the slopes of total 250 profiles distributed exponentially. In addition, the fractal dimension and power spectral density profiles were calculated. The results show that the fractal dimension of land fast ice in the Bohai Sea is about 1.132. The power spectral densities of 250 profiles can be expressed through an exponential autocorrelation function.
基金provided by the National Natural Science Foundation of China (No. 60777022)the Program for Young Excellent Tal-ents in Tongji University
文摘InAsSb epilayers with a cutoff wavelength of 4.8 μm have been successfully grown on InAs substrates by one-step liquid phase epitaxy （LPE） technology. The epilayers were characterized by X-ray diffraction （XRD）, Fourier transform infrared （PTIR） transmittance measurements and scanning electron microscopy （SEM）. The influence of different growth conditions on the optical and structural properties of the materials was studied. The results revealed that the good crystalline quality, mirror smooth surface and flat interface of InAsSb epilayers were achieved. They benefited from optimized growth conditions, i.e., sufficient homogeneity of the growth melt and a very slow cooling rate.
基金supported by National Natural Science Foundation of China(No.51201143)Fundamental Research Funds for the Central Universities (No.2682015CX001)+5 种基金China Postdoctoral Science Foundation(No.2015M570794)Key Laboratory of Infrared Imaging Materials and Detectors,Shanghai Institute of Technical Physics,Chinese Academy of Sciences(No.IIMDKFJJ-14-04)Sichuan Science and Technology Support Program(No.2016FZ0079)R&D Projects Funding from the Research Council of Norway(No.263875/H30)supported by the U.S. National Science Foundation No.1436120supported by DoD W911NF14-1-0060
文摘Diffusion bonding is a near net shape forming process that can join dissimilar materials through atomic diffusion under a high pressure at a high temperature.Titanium alloy TC4（Ti-6 Al-4 V）and 4 J29 Kovar alloy（Fe-29 Ni-17 Co）were diffusely bonded by a vacuum hot-press sintering process in the temperature range of 700-850°C and bonding time of 120 min,under a pressure of 34.66 MPa.Interfacial microstructures and intermetallic compounds of the diffusion-bonded joints were characterized by optical microscopy,scanning electron microscopy,X-ray diffraction（XRD）and energy dispersive spectroscopy（EDS）.The elemental diffusion across the interface was revealed by electron probe microanalysis.Mechanical properties of joints were investigated by micro Vickers hardness and tensile strength.Results of EDS and XRD indicated that（Fe,Co,Ni）-Ti,TiNi,Ti_2Ni,TiNi_2,Fe_2 Ti,Ti_（17） Mn_3 and Al_6 Ti_（19） were formed at the interface.When the bonding temperature was raised from 700 to 850°C,the voids of interface were reduced and intermetallic layers were widened.Maximum tensile strength of joints at 53.5 MPa was recorded by the sintering process at 850°C for 120 min.Fracture surface of the joint indicated brittle nature,and failure took place through interface of intermetallic compounds.Based on the mechanical properties and microstructure of the diffusion-bonded joints,diffusion mechanisms between Ti-6 Al-4 Vtitanium and Fe-29 Ni-17 Co Kovar alloys were analyzed in terms of elemental diffusion,nucleation and growth of grains,plastic deformation and formation of intermetallic compounds near the interface.
基金Supported by Joint Astronomical Fund of National Natural Science Foundation of China(U1831133)Key Laboratory of Space Active Opto-electronics Technology of Chinese Academy of Sciences(20212DKF4)Shanghai Natural Science Foundation(17ZR1443500)
文摘Aiming at the problems in a linear frequency modulation continuous wave(LFMCW)ranging lidar system,such as low signal-to-noise in echo beat frequency and difficult extraction of the signal frequency,a method with high-speed and high accuracy based on field programmable gate array(FPGA)is proposed.Firstly,the laser echo beat signal is sampled by high-speed analog to digital converter(ADC)and then processed in FPGA for data preprocessing.After the signal is processed by the 8192-point FPGA will obtain the frequency spectrum and then apply the frequency spectrum to data processing and adaptive noise signal peak detection.These two steps realize the real-time and accurate extraction process of the target echo beat signal frequency.Finally,the spectrum data is transmitted to the host computer and processed through the external data acquisition board for real-time spectrum display.Experimental results show that data preprocessing and spectrum data processing can effectively suppress DC bias and system modulation noise.Adaptive noise peak detection can accurately divide the threshold contour according to the dynamic noise of the system and realize the detection of target signal peak.When the sampling clock of the system is 100 MHz,the time needed for each calculation of the spectrum is 81.92μs,and the refresh rate of the spectrum reaches 12.2 kHz,which meets the real-time requirements of the system.
文摘Chang'E-1,the orbiter circling the moon 200km above the moon surface,is the first Chinese Lunar exploration satellite.The satellite was successfully launched on 24th October 2007.There are 8 kinds of scientific payloads onboard,including the stereo camera,the laser altimeter,the Sagnac-based interferometer image spectrometer,the Gamma ray spectrometer,the X-ray spectrom-eter,the microwave radiometer,the high energy particle detector,the solar wind plasma detector and a supporting payload data management system.Chang'E-1 opened her eyes to look at the moon and took the first batch of lunar pictures after her stereo camera was switched on in 20th November 2007.Henceforth all the instruments are successfully switched on one by one.After a period of parameter adjustment and initial check out,all scientific instruments are now in their normal operating phase.In this paper,the payloads and the initial observation results are introduced.
