Abstract:Measurement of basis weight which is one of the most important physical indexes of paper sheet is of decisive importance in paper making process.However,this problem has not been well solved so far.Terahertz time domain spectroscopy is a newly developed spectroscopy technique based on femtosecond laser technology,and has been studied in some other research fields.The purpose of this work is to study the feasibility of applying terahertz time-domain spectroscopy technique to the measurement of paper sheet ba...

Abstract:Liquid phase epitaxy is a developed technique for the growth of HgCdTe films.Two kinds of macro defects on the surface of HgCdTe film were studied.It was demonstrated that the origin of the void defects was related to the wax contamination on CdZnTe substrate,while the defects of hill-like were due to the CdZnTe particles detached from the edge of the CdZnTe substrate.Through the fine controlling during the substrate preparation,these two kinds of defects can be depressed and the high quality HgCdTe films w...

Abstract:Based on the optical readout method with knife edge filter,the relationship between the optical detection sensitivity and reflector length was discussed under the circumstance that the reflector was bent.Analysis indicates that the optical sensitivity increases with the reflector's lengthening at first,then it reaches a maximum value,and then it decreases as the reflector continues to lengthen.For the reflectors with different curvature radii and lengths,analysis shows that the sensitivity will reach a maxi...

Abstract:Aiming at the physical characteristics of infrared and visible imaging sensors,a novel image fusion algorithm based on the second generation Curvelet transform was proposed.Firstly,the fast discrete Curvelet transform was performed on the original images respectively to obtain the subband coefficients at different scales and in various directions.Then for low frequency subband coefficients,the fusion weights were determined by the target characteristics of infrared image and the detail information of visibl...

Abstract:PbWO4 and BaF2:PbWO4 were grown by multi-crucible temperature gradient system.The transmittance spectra and x-ray excited luminescence spectra of as-grown PbWO4,annealed PbWO4 and annealed BaF2:PbWO4 were studied.The results reveal that these properties are related to the composition and growth arts of the crystals.The facts are complicated for the crystals annealing.In the wavelength range above 360nm,the transmittance for the annealed crystal is better than that of the as-grown crystal,while it is a littl...

Abstract:由球形水滴组成并分布在大气底层的水云,对全球辐射平衡和气候变化有重要的影响,其影响程度取决于水云本身的微物理特性和光学特性.在对近红外通道0.865μm波长处水云光学特性研究的基础上,采用矢量辐射传输方程模拟分析了大气层顶归一化辐射强度和归一化偏振辐射强度对水云微物理特征、光学特征和地表反照率的敏感性.模拟结果表明,光谱的多角度偏振遥感信息能够更有效地体现出水云微物理特征和光学特征,可以利用多角度偏振遥感信息反演各种云参数.为利用多角度偏振遥感数据反演水云各种微物理量提供了理论基础.

Abstract:For the rapid detection of SPAD value of cucumber leaves,the calibration model of SPAD value was built by using visible and near infrared(Vis/NIR) spectroscopy technique and chemometrics methods.Different calibration methods were used to build the model in the whole wavelength region.The results indicate that the optimal performance is achieved by least squares support vector machine(LSSVM) model,and the correlation coefficient(r) and root mean squares error of prediction(RMSEP) are 0.9583 and 0.9732,respec...

Abstract:The Fourier transform mid-infrared(FT-MIR) spectra and nitrogen concentration were measured from dried leaves of rice in booting stage under various treatments of nitrogen fertilization.The synergy interval partial least square algorithm(si-PLS) combined with genetic algorithm(GA) was applied to the selection of optimal variables.84 variables were determined to build the estimation model for leaf nitrogen content.The prediction accuracy of the PLS regression model based on these variables was better than th...

Abstract:Requirements on color image fusion for situation awareness and target detection tasks were analyzed based on the characteristics of human visual system.Then a night vision fusion method was presented to improve target detectability by enhancing color contrast between the target and the background.The proposed fusion method relates hot and cold targets to the colors of intense red and cyan,respectively.According to the characteristics of infrared images,a color contrast enhancement ratio related to the diver...

Abstract:Laser altimeter's field of view(FOV) is an important parameter affecting system's performance.The effect of the field of view on the detection performance of system was discussed.Because of the straylight and the sensor's nonuniformity,the FOV changes as the echo's power changes.At the same time the echo's power will be varied with the detecting distance.The testing way of detecting FOV was put forward,and the factual working status was simulated.For system with inner short-range delay protecting circuit,a ...

Abstract:Thermal emission characteristics of a negative index semitransparent thin film were studied based on transmit matrix method and Kirchhoff radiation law.The influence of different parameters on the emissivity of s-polarization wave was studied.The results show that a complicated oscillation will happen when the angular frequency increases.It also shows that the peak value of the emissivity is sometimes far away from the normal direction.

Abstract:Many existing detecting algorithms of salient object mostly depend on the relationship between the pixels and lack the comprehension of salient object features.An unsupervised algorithm for automatically extracting the interesting object was presented.Firstly,the junior feature was extracted as basic elements of salient object by using a multiscale Gabor model with bionics characteristics.Then by combining with the understanding knowledge of the salient object,the local feature of image was defined and the ...

Abstract:Based on compressed sensing(CS),a new multiple description coding method(CS-MDC) was presented.The new method is robust to packet loss or bit error,and has the advantages of simple structure and easy implementation.The method partitioned an image into several blocks by interleaving extracting in the wavelet domain,and made random measurements of the image blocks,and then formed multiple descriptions after quantizing and packing.At the decoding end,it reconstructed the original image approximately or exactly...

Abstract:In ultrafast optical coherent control,the existence of the phase distortion and phase inconsistence on fundamental frequency and its second harmonic generation laser wavefront leads to fail to achieve the desired experiment results in most cases.An experimental method in diagnosing such distortion situation was designed to make an effective auto-control system applied sucessfully in the coherent control photocurrent experiments.The retrieval algorithm was used,and the spatial surface structure was calculate...

Abstract:可见+1.54μm激光/长波红外分色片分离可见光、激光和长波红外光,在多通道成像光学系统中起着重要的作用.分析了分色片基板和薄膜材料的选择,优化设计并用电子束蒸发法制备了该分色片,其反射率和透射率都达到了94%以上,已成功应用于实际光学系统.

Abstract:A novel SAR image compression algorithm was presented by using lifting directionlet transform(LDT).The lifting directionlet scheme and improved quad-tree segmentation were proposed to obtain the optimal pair of transform directions,which could capture the image features efficiently.To enhance the coder performance,multi-directional anisotropy hierarchical zerotree was designed,which was suitable to the distribution characteristic of LDT coefficients.Experimental results of real SAR images show that the prop...

Abstract:The objects' spectrum is often contaminated by noise when it is collected in the open air.According to the principle of the spectrum collection,the noise was considered as one kind of multiplicative compound noise.By theoretical derivation,the combination of logarithm transform and wavelet transform was introduced into noise reduction.Multiplicative noise simulation test was carried out.And the results show that the spatial correlation algorithm is best suited for spectral data denoising,modulus maxima algo...