FTIR测量的量子型光电探测器响应光谱校正

针对采用FTIR方法测量量子型光电探测器的光电流谱并据此校正获得器件的实际响应光谱问题,提出了两种简便可行的校正方案,即计算仪器函数校正方案和标准探测器传递校正方案;对其可行性、限制因素及注意事项进行了详细讨论.用两种方案对多种短波红外InGaAs光电探测器进行了测量校正,获得了与实际符合的响应光谱.为验证方案的适用性,还与采用经精确标定的光栅分光测量系统测得的结果进行了比对,确认了其适用性.结果表明,采用FTIR测量方法并结合适当的校正方案可以获得符合实际的响应光谱.     

ATR/FTIR技术和红外透射法用于蔬菜中农药含量测定的比较研究

从理论和样品分析两方面比较了ATR/FTIR技术和红外透射法,并分别用这两种红外技术测定了蔬菜中氯氰菊酯含量.结果表明:氯氰菊酯在916cm-1处的吸收峰不受青菜叶谱图干扰,可选择此峰为定量分析波数.以峰面积定量,运用ATR/FTIR技术和红外透射法分别得到峰面积Y和样品浓度X的线性方程:y=1.423x-0.0021,相关系数R=0.9979;y=26.025x-2.2847,相关系数R=0.9971,其最低检出线分别为0.01 mg和0.15 mg.ATR/FTIR技术相对于传统红外透射法其测定灵敏度更高,且完全不需对样品进行预处理.     

全数字闭环石英挠性加速度计系统校正与仿真

针对石英挠性加速度计模拟伺服方案存在精度损失问题。采用全数字闭环的检测方法,提出一种以传递函数校正的控制方案,通过引入积分环节和补偿校正装置消除系统的一阶静态误差,以获得足够的相位裕度。同时对校正装置进行离散化处理,建立了离散域数字闭环系统模型。基于此模型进行仿真与研究,校正后系统超调量在19%,-3dB带宽在1417Hz左右。离散域与连续域阶跃曲线特性基本相同,仿真结果与理论基本一致。验证了数字闭环系统校正方法的正确性和可行性。     

超快电磁脉冲辐射的产生与检测

本文报道了一种产生超快电磁脉冲辐射并对其进行检测的方法。利用飞秒级超快激光脉冲照射半导体样品，并通过采用一种特殊结构电光采样进行接收，我们测得了脉宽为３００飞秒的电磁脉冲辐射。     

中大功率单相功率因数校正器的设计与实现

采用有源功率因数校正技术(active power factor correction,APFC)设计并实现了一款高功率因数、高效率、低谐波、低噪声的"绿色"功率因数校正装置.1700 W样机实验结果表明:所设计的功率因数校正装置能在165～275 V AC宽电压范围内,得到稳定的直流电压输出;输入交流电流能很好的跟踪...     

基于等效平行轨迹距离模型的双基CS成像算法

本文基于双基SAR等效平行轨迹距离模型及由该模型得到的二维波数域表达式,通过对此表达式的分析变换,将二维波数域表达式的相位表示为发收距离和与波数函数相乘的形式,基于此,结合单基SAR的CS成像算法思想,推导提出了基于平行轨迹距离模型的双基CS成像算法.本算法在距离多普勒域进行变标操作,将各距离单元的包络徙动校正得和参考距离单元一致,然后在二维波数域通过简单的相位相乘完成徙动校正,很好地解决了双基SAR的包络徙动及其空变问题,且避免了插值运算,与波数域算法相比,效率更高.最后采用该算法对仿真的点目标双基回波进行成像处理,结果与等效单基CS算法相比较,证明了本文算法的有效性和优越性.     

傅里叶变换红外光谱信息处理中的波数校正

折射式扫描干涉仪与传统干涉仪相比具有高稳定性和高光通量等优点,但其光程的改变是由补偿光楔的运动产生的,其结构也导致了不同波长的光经过的光程不同,从而导致了由干涉图变换出来的光谱在波数上有偏差.采用的波数校正方法很好的解决了这一问题,并具有很高的精度.     

基于MATLAB的液位控制系统仿真与校正

在采用了合理的实际参数值的基础上,建立了液位控制系统的数学模型即传递函数模型,再利用MATLAB对原系统传递函数模型进行仿真并分析其时域性能指标和频域性能指标是否达到实际工作中的相关要求.若某些指标不能满足相关要求,则需要考虑利用PI控制器、滞后-超前校正或最优控制等校正方法设计校正装置对原系统进行校正直至得到合理的校正方案.通过比较各个校正方案的校正结果,可知在串联积分环节后再采用滞后-超前校正是最佳校正方案,此方案完全消除了原系统的静态误差,并使得超调量降为16.7%,调节时间降为4.18s,达到了较为理想的校正目的.     

基于IC控制器CM6800的LCD电视机电源设计

以新一代功率因数校正芯片CM6800为核心,提出了一种宽电压输入、固定电压输出的LCD电视机电源的设计方案,重点讲述了CM6800的主要特性及各主要器件参数选择。该方案能在80~265 V宽输入电压范围内得到稳定直流电压输出,具有效率高、总谐波畸变率低、功率因数接近为1等特点。该方案完全能满足LCD电视机电源的要求,并已得到成功应用。     

红外多光谱遥感数据的校准

主要介绍了一种对由特定红外图谱一体化系统采集的光谱数据进行校准与分析的方法。在实验部分,首先对得到的设定已知特定温度的黑体红外光谱数据进行归类和整理,然后在最大保留特征信号的条件下利用不同的滤波算法与滤波窗宽尽量消除信号噪声,并采用偏最小二乘算法对所得信号进行校准,使之与理论值相符。最后利用校准结果构建数学模型,并考虑主成分个数这一概念,检验模型准确度。通过数据分析可知,由这个特定红外图谱一体化系统采集的光谱数据经偏最小二乘算法校正后与理论值相近,此时能够拟合出校正数列与波数之间的函数关系,且受温度影响较小。     

Nanometer fabrication techniques for wide-gap II-VI semiconductors and their optical characterization

We have fabricated dots and wires down to 30 nm diameter and 60 nm width in ZnTe/GaAs and ZnSe/GaAs. The fabrication process relies on electron beam lithography and dry etching using a mixture of CH₄/H₂. We have extensively characterized the flat etched surfaces of both ZnTe and ZnSe using x-ray photoelectron spectroscopy (XPS), Raman scattering, and luminescence spectroscopy. Flat etched samples were also annealed. We found that improvements in the emission spectrum were related probably to defect removal in the asgrown samples and had a secondary impact in the etched and annealed samples. From XPS data, some evidence is found of zinc desorption from the surface, which is later corroborated by Raman scattering in etched wires with the appearance of tellurium modes. The luminescence spectra of flat etched samples show no major changes in the spectral lines, with a hint of a change in relative concentration in donors and acceptors and evidence of ZnTe/GaAs intermixing closer to the interface. No line broadening is observed and the emission intensity is retained. The emission and Raman scattering spectra of etched wires and dots confirms that negligible fabrication damage is incurred as well as the absence of further strain or strain release after etching.     

Effect of Yb^3＋ concentration on Er^3＋ luminescence properties of sol-gelderived silica-alumina xerogels

Er~(3 )-activated silicate glasses are recognized of tech-nological interest in several areas and,in particular ,it iswell known for their successful application in opticalamplification at the C band (1530 -1565 nm) of tele-communications[1].Inside this l…     

红外上转换材料CaS：Eu，Sm的制备

采用碳还原法，制备了电子俘获型红外上转换材料（CaS：Eu，Sm）．研究了反应机理、还原原理、红外上转换机理以及灼烧温度对CaS品格形成和发光性能的影响．样品的XRD测试结果表明，CaS：Eu，Sm为面心立方结构，样品的激发谱位于200—600nm，样品的荧光发射光谱是峰值分别位于567nm，606nm和630nm的宽带谱，上转换发光峰值位于625nm，上转换发光的光谱响应范围位于800～1600nm．     

Platform for enhanced detection efficiency in luminescence-based sensors

Luminescence-based biochip measurement platforms are employed in a wide range of biological applications, such as biomedical diagnostics. Based on an understanding of the anisotropic emission properties of luminescence emitters close to a dielectric interface, a simple strategy for producing a better than 25-fold enhancement of the detected luminescence is presented. This strategy is demonstrated for low cost polymer platforms compatible with mass-production.     

纳米ZnO光学性质研究进展

介绍了纳米ZnO常见发光谱的发光机制。在室温光致发光谱(PL)中,一般在380 nm处出现紫外发光,也有报道在357和377 nm处的紫外发光,列举了几种不同的发光解释。对于深能级发光,一般在400～550 nm出现连续的发光带,也有观察到深能级的声子伴线和声子复制现象。在低温光致发光谱的紫外发射中,一般观察到由自由激子发射(FX)、中性施主束缚激子发射(D0X)、施主-受主对跃迁峰(DAP)、中性施主束缚激子对应的双电子卫星峰(TES)以及声子伴线。综述了纳米ZnO的喇曼光谱、透射光谱、电致发光谱(EL)的特征,最后展望了纳米ZnO的光学性能研究前景。     

Optical Characterization of Ag Nanoparticles Embedded in Aluminophosphate Glass

An aluminophosphate glass system containing silver and tin was prepared by the melt-quenching technique in which spherical silver nanoparticles (NPs) of different sizes were embedded upon heat treatment. Optical absorption was used in the assessment of particle growth and for particle size estimation yielding mean radii in the 10–40 nm range. Measurements in the UV region revealed absorption features indicative of the occurrence of silver ions and twofold-coordinated tin centers. Photoluminescence spectroscopy excited at 355 nm showed a broadband emission around 420 nm for the non-heat-treated glass, which shows a thermal quenching effect in temperature dependence measurements. Heat-treated glass shows a dip in the emission spectrum ascribed to absorption by NPs. The luminescence is attributed to single Ag⁺ ions. The nature of the silver emitting states is discussed.     

Radiative recombination in GaN nanocrystals at high intensities of optical excitation

The spectra of spontaneous UV luminescence of GaN nanocrystals excited by optical pumping at power densities ranging from 50 W/cm² to 50 MW/cm² are studied. At room temperature, radiation peaks related to the emission of free excitons and recombination of electron-hole plasma are revealed. The spectral characteristics of the emission of the electron-hole plasma in GaN is studied in the wide temperature range of 77–550 K.     

Photoluminescence study of ZnO varistor stability

Photoluminescence (PL) measurements were carried out on commercial ZnO varistor samples that were electrically stressed and/or annealed at different temperatures. Changes in the intensity of green and yellow luminescence centers were studied as a function of annealing treatment. It was found that the ZnO luminescence (green and yellow) decrease with increase in annealing temperature, reach a minimum at 700°C, and increase again beyond 800°C. Furthermore, these green and yellow luminescence bands observed in the PL spectra are quenched in the ZnO varistor samples, compared to pure ZnO. In an electrically stressed ZnO varistor sample, the luminescence intensity was found to be higher compared to the as-sintered varistor sample. Annealing of the stressed varistor sample resulted in a decrease of the luminescence intensity. These PL observations are consistent with previous deep level transient spectroscopy and doppler positron annihilation spectroscopy results. All of the experimental results are consistent with the ion migration model of degradation and can be explained using a grain boundary defect model.     

Temperature behavior of bright luminescence from LPE-grown Ga1-xAlxP structures

Luminescent properties of LPE-grown Ga1-xAlxP (0 leq x geq 0.3) structures have been studied over a wide temperature range. The complicated character of low-temperature luminescence is attributed to intrinsic and impurity-related recombination. The essential dependence of free exciton recombination upon temperature and composition is established for radiative Ga1-xAlxP structures. Anomalous and normal dependence of radiative efficiency on temperature has been shown to be characteristic of intrinsic and impurity-related luminescence. Thus the temperature dependence of the total luminescence can be controlled simply by varying the donor impurity doping level. LED's with luminous intensityI_{V}= 2mcd atT = 300K have been fabricated from the LPE-grown Ga1-xAlxP p-n structures which have high temperature stability of injection and breakdown luminescence efficiency, and emission band spectral position.     

Ultraviolet luminescence of ZnO infiltrated into an opal matrix

Technology for the infiltration of zinc oxide into a three-dimensional opal lattice using chemical deposition from a solution was developed. Samples of ZnO-opal composites, whose luminescence at room temperature mainly occurs in the ultraviolet spectral range, were obtained. The filling ratio was monitored by two different techniques: (i) checking the increase in the mass of the sample and (ii) checking the shift of the peak in the optical reflection spectrum of samples filled with ZnO in comparison with the initial opal matrices. The results obtained by these two methods are consistent with each other. Optimum conditions for synthesizing ZnO-filled opals in order to attain the highest intensity of ultraviolet luminescence were determined. It was shown that using “raw” opals, whose voids are incompletely filled with the semiconductor material, leads to a severalfold increase in the intensity of the edge excitonic emission band at room temperature. The results obtained can be used in the development of efficient directed laser light sources in the ultraviolet spectral range based on the “photonic crystal” effect.