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Contents
2004
Volume: 23 Issue 4
17 Article(s)
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Research Article
MAGNETIC ANDMAGNETO-OPTICAL PROPERTIES OF Mn/Sb MULTILAYER FILMS
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Mn/Sb multilayer filmswith different thicknesses were grown on GaAs(100) and glass by ultrahigh vacuum(UHV)evaporation technique and then annealing for a short duration(1 or 20 min). Magnetizationmeasurements revealed strong room temperature ferromagnetism. And when the thickness oflayers was increased from 700 to 1600Mn/Sb multilayer filmswith different thicknesses were grown on GaAs(100) and glass by ultrahigh vacuum(UHV)evaporation technique and then annealing for a short duration(1 or 20 min). Magnetizationmeasurements revealed strong room temperature ferromagnetism. And when the thickness oflayers was increased from 700 to 1600,the saturation magnetization increased nearlydouble; and the polar and longitudinal Kerr saturation angles θk increased too, but less than two times. It indicates that both themagnetization and Kerr rotation angle depend on the thickness of layers, but are notsimply proportional to the thickness of the layers. The saturation magnetization and boththe polar and longitudinal Kerr saturation angles can be enhanced with increasing thethickness of the layers. X ray diffraction(XRD) pattern results show that high qualitycrystal structures of thicker Mn/Sb films can be fabricated by UHV evaporation techniquewith subsequent thermal annealing for a very short duration(about 1 min)..
Journal of Infrared and Millimeter Waves
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 4, 241 (2004)
ANALYSIS OF MODULATING CHOPPER USED IN PYROELECTRIC UNCOOLED FPA THERMAL IMAGER--CHOPPER'S EXPOSURE EFFICIENCY
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The archimedes spiral cord modulating chopper's exposure efficiency was theoretically analyzed and numerical simulated, and its impact on the following signal processing was obtained. Results show that chopper's exposure efficiency directly affects detector pixels' exposure time and incident radiation, and The archimedes spiral cord modulating chopper's exposure efficiency was theoretically analyzed and numerical simulated, and its impact on the following signal processing was obtained. Results show that chopper's exposure efficiency directly affects detector pixels' exposure time and incident radiation, and affects the detector pixels' effective accumulated charge's uniformity with detector's signal readout time coordinately. Modulating synchronization locating point should be added in the chopper, which can make thermal imager be compatible with different exposure efficiency chopper. The effect of the chopper's exposure efficiency should be synthetically considered when the whole thermal imaging system and its electronic processing system are designed..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 246 (2004)
NEW APPROACH TO NONUNIFORMITY CORRECTION OF IRFPA WITH NONLINEAR RESPONSE
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Aiming at the nonlinearity of photoresponse characteristic in infrared focal plane arrays, a new approach to nonuniformity correction in IRFPA was proposed, which is simple and easy to implement by hardware circuit. The theoretical analysis and comparisons of simulation results show its performance is more perfect thanAiming at the nonlinearity of photoresponse characteristic in infrared focal plane arrays, a new approach to nonuniformity correction in IRFPA was proposed, which is simple and easy to implement by hardware circuit. The theoretical analysis and comparisons of simulation results show its performance is more perfect than that of the piecewise linear algorithm and the polynomial fitting algorithm, and only a few correction factors are needed..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 251 (2004)
ANALYSIS OF SCENE-BASED TECHNIQUES FOR NONUNIFORMITY CORRECTION OF INFRARED FOCAL PLANE ARRAYS
[in Chinese], and [in Chinese]
Compensating for temporal drift of fixed-pattern noise is an important problem in the techniques for nonuniformity correction of infrared focal plane arrays. Kalman-filtering algorithm, statistical algorithm and algebraic algorithm were examined here. The mechanism for solving temporal drift of the fixed-pattern noise Compensating for temporal drift of fixed-pattern noise is an important problem in the techniques for nonuniformity correction of infrared focal plane arrays. Kalman-filtering algorithm, statistical algorithm and algebraic algorithm were examined here. The mechanism for solving temporal drift of the fixed-pattern noise was analyed, and these algorithms performance were comprehensively evaluated. Our conclusions are verified by the simulation data..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 257 (2004)
STUDY ON REFRACTIVE INDEX OF GaN BY SPECTROSCOPIC ELLIPSOMETRY
[in Chinese], [in Chinese], and [in Chinese]
Unintentionally doped wurtzite GaN grown on (0001) sapphire was studied by spectroscopic ellipsometry(SE) in the wavelength range of 400～1200nm. Both the thickness and dispersion of the refractive index of GaN, i.e. n2(λ)=2.262+330.12/((λ/nm)2-265.72), were obtained by fitting the experimental data. With this formula, Unintentionally doped wurtzite GaN grown on (0001) sapphire was studied by spectroscopic ellipsometry(SE) in the wavelength range of 400～1200nm. Both the thickness and dispersion of the refractive index of GaN, i.e. n2(λ)=2.262+330.12/((λ/nm)2-265.72), were obtained by fitting the experimental data. With this formula, the reflection spectrum of GaN in the UV-VIS range was studied and the thickness of GaN was calculated. The two values of the thickness obtained by these two different methods are in good agreement and the deviation is found to be 0.68%..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 262 (2004)
RESEARCH ON A NOVEL 3D-DWT-SPIHT CODING BY ALTERNATE GROUPS OF ORIGINAL AND RESIDUAL ERROR FRAME
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An improved method that uses 3D-DWT-SPIHT in original video group and residual error group alternatively was proposed. In addition, the multi-wavelet bases were combined in time domain. The proposed method reduces coding latency time and releases memory requirement, and improves both compression efficiency and reconstrAn improved method that uses 3D-DWT-SPIHT in original video group and residual error group alternatively was proposed. In addition, the multi-wavelet bases were combined in time domain. The proposed method reduces coding latency time and releases memory requirement, and improves both compression efficiency and reconstructive image's quality, especially to the video sequences with complicated background. Simulation results show that, in the case of equal compression ratio and memory space, our method has higher quality(PSNR above 1dB) than available methods. It is still slightly better than others', when memory is reduced to half..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 265 (2004)
FIRST PRINCIPLES CALCULATION OF THE BAND STRUCTURE OF CdTe AND HgTe
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The electronic band structures of CdTe and HgTe were calculated with FLAPW method based on first Principles density functional theory. The Brent method was introduced to optimize the lattice constant. In comparison with conventional methods the Brent method can give more accurate and faster result. The result of band sThe electronic band structures of CdTe and HgTe were calculated with FLAPW method based on first Principles density functional theory. The Brent method was introduced to optimize the lattice constant. In comparison with conventional methods the Brent method can give more accurate and faster result. The result of band structure and density of state presented here well agree with experiment, moreover the results based on LSDA and GGA are compared and discussed..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 271 (2004)
MAKING MAGNETO-OPTIC CE-SUBSTITUTED YIG THIN FILMS ON AMORPHOUS SILICA SUBSTRATE
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The preparation and magneto-optic properties of YIG thin films were investigated. Ce-substituted yttriumiron garnet(Ce 1YIG) thin films were grown on an amorphous silica substrate by RF magnetron sputtering method. Then the as-grown amorphous Ce 1YIG thin films were annealing in different ambient gas to obtain the crysThe preparation and magneto-optic properties of YIG thin films were investigated. Ce-substituted yttriumiron garnet(Ce 1YIG) thin films were grown on an amorphous silica substrate by RF magnetron sputtering method. Then the as-grown amorphous Ce 1YIG thin films were annealing in different ambient gas to obtain the crystallized film with magneto-optic effect. The post annealing process was investigated in detail, and the influence of microstructure of films on magntooptic properties was discussed. The results show that the saturation Faraday rotation coefficient θ F of about 0.8deg/μm was obtained for light at a wavelength of 630 nm, and the strong in-plane magnetization was observed. The curie temperature is 220℃ measured by VSM at atmosphere. All these parameters show that Ce∶YIG thin film prepared is suitable for fabrication of magnetooptic waveguide isolator..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 276 (2004)
IDETIFYING OF NOISE TYPES AND ESTIMATING OF NOISE LEVEL FOR A NOISY IMAGE IN THE WAVELET DOMAIN
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel methodology for identifying noise types and estimating noise level was reported. The energy distribution of the HH subband's coefficients in the wavelet domain was used to distinguish Gaussian white noise and salt & pepper noise, which exist in images frequently. And the variance of the Gaussian white nA novel methodology for identifying noise types and estimating noise level was reported. The energy distribution of the HH subband's coefficients in the wavelet domain was used to distinguish Gaussian white noise and salt & pepper noise, which exist in images frequently. And the variance of the Gaussian white noise and the density of salt & pepper noise were estimated. The experiments on a wide variety of images indicate the veracity of distinguishing and estimating of noise..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 281 (2004)
ALGORITHM ON SMALL TARGET DETECTION BASE ON PRINCIPAL COMPONENT OF HYPERSPECTRAL IMAGERY
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A small target detection approach which is based on principal component of hyperspectral imagery was presented. As a kind of multivariate data, the points of hyperspectral data always compose a hyper-plane in high-dimensional space. The principal component analysis can estimate the intrinsic dimensionality of the hyperA small target detection approach which is based on principal component of hyperspectral imagery was presented. As a kind of multivariate data, the points of hyperspectral data always compose a hyper-plane in high-dimensional space. The principal component analysis can estimate the intrinsic dimensionality of the hyper-plane.Usually, the significant components contain most information of imagery. The insignificant components, which covers important details such as target characteristic, represent the information of orthogonal subspace. These insignificant principle components were used to detect small targets. This method reduces the dependent of the spectral pre-information and improves the practicability..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 286 (2004)
DISGN AND ANALYSIS OF MILLIMETER TRAVELING-WAVE ELECTROABSORPTION MODULATOR'S ELECTRODE
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The bandwidth of the coplanar traveling-wave electroabsorption modulator(TW-EAM) was analyzed in the aspect of designing electrode. The calculation process of this method was introduced by demostrating designing a coplanar TW-EAM with its measured data. The demostrating result tallies with the result of experimental meThe bandwidth of the coplanar traveling-wave electroabsorption modulator(TW-EAM) was analyzed in the aspect of designing electrode. The calculation process of this method was introduced by demostrating designing a coplanar TW-EAM with its measured data. The demostrating result tallies with the result of experimental measure. It was analyzed the effect of the width of middle electrode and the electrode interval on the bandwidth. An example is also introduced that a GaAs/GaAlAs multiple quantum wells(MQWs) TW-EAM with alarge bandwidth which was designed by using this method..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 291 (2004)
RESEARCH OF BOMB-BORNE 3mm THREE BEAMS DETECTION SYSTEM WITH CASSEGRAIN ANTENNA
[in Chinese], [in Chinese], and [in Chinese]
A design of 3mm passive millimeter wave multi-beam detection system was proposed on the background of bomb-borne application. The system can form three channels with just one receiver and two groups of PINs. After introducing the principle of the system, the main parameters of the system were designed detailed. AnalysiA design of 3mm passive millimeter wave multi-beam detection system was proposed on the background of bomb-borne application. The system can form three channels with just one receiver and two groups of PINs. After introducing the principle of the system, the main parameters of the system were designed detailed. Analysis and experiment show that the design is feasible..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 295 (2004)
CLASSIFICATION ALGORITHM BASED ON SPATIAL CONTINUITY FOR HYPERSPECTRAL IMAGE
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on the spatial continuity of ground objects, a new classification algorithm was proposed by two steps, namely blocking images followed by further classification, which improved the disadvantage of the general classification algorithms constrained by only spectral information. The new algorithm proposed in this stBased on the spatial continuity of ground objects, a new classification algorithm was proposed by two steps, namely blocking images followed by further classification, which improved the disadvantage of the general classification algorithms constrained by only spectral information. The new algorithm proposed in this study was validated by the 80-band hyperspectral image acquired by the push broom hyperspectral imager(PHI) in Minamimaki of Japan, 2000. The PHI sensor was developed by the Shanghai Institute of Technical Physics. It turned out that our algorithm embodied the advantage in classifying hyperspectral image..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 299 (2004)
DESIGN OF DWDM NARROW BAND FILTERS WITH ITERATIVE CHEBYSHEV METHOD
[in Chinese], and [in Chinese]
A simple but valuable iterative Chebyshev design method was presented. By studying the design procedure of Chebyshev band pass filters, we pointed out that it is the phase variation that results in the remarkable narrowing in the final pass band. Beginning with some larger initial values, one can arrive at satisfactoryA simple but valuable iterative Chebyshev design method was presented. By studying the design procedure of Chebyshev band pass filters, we pointed out that it is the phase variation that results in the remarkable narrowing in the final pass band. Beginning with some larger initial values, one can arrive at satisfactory results after several simple iterations without calculating the phase property of reflective stacks. The results of adding interference orders and ripples to the iteration procedures was discussed. The design block diagrams and some actual design results were given. The basic principle of this method is to realize a direction-controlled optimization through different iterative procedures..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 303 (2004)
INFRARED DIFFRACTIVE OPTICAL ELEMENT FABRICATED ON ASPHERIC SUBSTRATE
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A hybrid diffractive-refractive infrared lens of Germanium was fabricated by means of diamond turning, in which the diffractive surface was produced on an aspheric substrate. Test results for the hybrid lens and a comparative lens without the diffractive structure showed that the diffractive surface was fabricated withA hybrid diffractive-refractive infrared lens of Germanium was fabricated by means of diamond turning, in which the diffractive surface was produced on an aspheric substrate. Test results for the hybrid lens and a comparative lens without the diffractive structure showed that the diffractive surface was fabricated with good accuracy. It effectively reduced the chromatic aberration of the single lens system, and significantly improved the image quality of the system, which corresponds well to the design result..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 308 (2004)
INFLUENCE OF DEPOSITION POWER ON THE COMPOSITION,STRUCTURE AND PROPERTIES OF PZT THIN FILMS PREPARED BY RF SPUTTERING
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
PbZr0.52Ti0.48O3(PZT) ferroelectric thin films were deposited on LaNiO3 coated p-Si(111) substrates by RF magnetron sputtering at low substrate temperature( T =370℃) with deposition power ranging from 60W to 120W, sequentially followed by a rapid thermal annealing(RTA) process at temperature 650℃ for 5 minutes. The cryPbZr0.52Ti0.48O3(PZT) ferroelectric thin films were deposited on LaNiO3 coated p-Si(111) substrates by RF magnetron sputtering at low substrate temperature( T =370℃) with deposition power ranging from 60W to 120W, sequentially followed by a rapid thermal annealing(RTA) process at temperature 650℃ for 5 minutes. The crystalline phase, microstructure, composition, and electrical properties of PZT thin films were investigated by X-ray diffraction(XRD), canning electron microscope(SEM), inductively coupled plasma-atom emission spectrometry (ICP-AES), four-probe meter and spectro-ellipsometer, respectively. It is found that the microstructure, composition and electrical properties of sputtered PZT thin films are highly dependent on the deposition power, i.e., the atom rate Pb(Zr+Ti) of PZT films and the leak-current of Pt/PZT/LNO capacitors increase as the deposition power increases, films deposited at low power are Pb-poor and present nonferroelectricity, while those deposited at high power are Pb-rich.Optimized deposition power is 80W..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 313 (2004)
IFLUENCE OF GRAIN BOUNDARY TUNNELING ON THE RESISTIVITY OF THE VO2 FILMS PREPARED BY SOL-GEL METHOD
[in Chinese], [in Chinese], and [in Chinese]
Based on the model of the two phases of grain and grain boundary, the grain boundary tunneling of carriers was considered to simulate the change of the resistivtiy of VO2 polycrystalline film prepared by Sol-gel method in temperature range of 10℃～100℃.The simulation results were in good agreement with the experiment daBased on the model of the two phases of grain and grain boundary, the grain boundary tunneling of carriers was considered to simulate the change of the resistivtiy of VO2 polycrystalline film prepared by Sol-gel method in temperature range of 10℃～100℃.The simulation results were in good agreement with the experiment data. The results indicate that the grain boundary effect decreases the magnitude of resistivity change of VO2 film durying semiconductor-to-metal phase transition, and meanwhile the VO 2 film in metal phase has a negative temperature coefficient of resistivity..
Journal of Infrared and Millimeter Waves
- Publication Date: Aug. 01, 2004
- Vol. 23, Issue 4, 317 (2004)
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