红外光谱响应度测试系统研究

红外光谱响应度是红外探测领域的重要技术指标。介绍了红外光谱响应度的测试技术及其测试系统。该系统选用以无光谱选择的腔体热释电探测器为标准,用双单色仪进行分光同时,采用国际上最新的测试方法完成了红外波段光谱响应度的测量,获得了高的测量不确定度,分析了测试结果及其影响因素。     

Characterization of silicon photodiode-based trap detectors and establishment of spectral responsivity scale

Spectral responsivity scale was established at National Metrology Institute of Turkey (UME) between 350 and 850 nm wavelength ranges. The scale is based on UME made reflection type trap detector consisting of three single element silicon photodiodes. Various measurements systems were established in order to make optical characterization of trap detectors like linearity, polarization sensivity, uniformity and spectral responsivity. The absolute responsivity linked to the absolute optical power was obtained using improved laser stabilization optics and electrical substitution cryogenic radiometer system at discrete laser wavelengths. Using physical models for the trap detectors, reflectance and internal quantum efficiency the scale was realized with an expanded uncertainty of 0.05%.     

功率效应对功率LED热阻的影响

分析比较了在不同输入功率条件下1 W GaN基LED样品的热学特性,得出了有效热阻随加载功率的变化规律。基于瞬态热测试方法,讨论了结-环境热阻与输入功率之间的关系。加载电流为100~500 mA的区域随着电功率增加,有效热阻明显降低;当电流增至500 mA以上时,有效热阻减小幅度越来越小;而当加载电流为900~1 650 mA时,结-环境的热阻随着电功率的增加而缓慢升高。随着注入电功率的增加,在不同电流区域同一个样品的热阻变化趋势却是相反的,这个现象归因于串联电阻热耦合随输入功率的变化。该结果对分析功率型LED热特性具有一定参考价值。     

硅陷阱探测器在350—1064 nm波段的绝对光谱响应度定标

介绍了利用钛宝石可调谐激光器、倍频器和单波长激光器作为光源,在24个波长分立点定标了三个硅陷阱探测器的绝对光谱响应度,解决了红外激光的精确定位与调整、窗口透过率模拟定标等关键技术.结果显示：在激光波长为412—800nm时,三个陷阱探测器定标的不确定度约低于0.05％;当激光波长大于800nm以及低于355nm时,获得的陷阱探测器的定标不确定度约低于0.065％.硅陷阱探测器可以作为空间各类遥感器在350—1064nm波段定标的传递标准探测器. 关键词： 陷阱探测器 低温辐射计 光谱响应度 辐射定标     

基于光源近场模型的LED光学扩展量测量方法

基于精确的LED光源近场模型,提出了一种LED光学扩展量测量方法.通过追迹LED近场光源模型中的光线数据,可获得LED光功率关于光学扩展量的关系曲线,直观反映出LED光源的光学扩展量特性和光能利用率等信息.以紫外曝光系统中的UV-LED阵列面光源为例,对三款不同型号的UV-LED进行了实际测量.通过测量得到的光学扩展量和光能利用率曲线,可以对UV-LED的光束质量作出判断,并为阵列面光源的优化设计提供帮助.     

照明光源及纸张色彩对传统书法作品展陈喜好的影响

书法是中国传统文化独有的文字艺术表现形式。书法作品的展陈喜好,其实质为色彩组合喜好中的色彩图形喜好问题。本研究针对现阶段书法作品展陈方式在颜色科学层面缺乏合理依据的问题,以主客观实验为基础,就照明光源及纸张色彩对传统书法展陈喜好的影响进行了分析与讨论。研究首先通过相关色温2 500, 3 500, 4 500, 5 500和6 500 K共五种典型LED照明光源相对光谱功率分布以及白色、黄白、浅白、红色、橙色共五种典型书法纸张光谱反射率信息的测量,获取光源及纸张色彩原始信息,并分别将其转换至CIEXYZ以及CIECAM02颜色空间。随后,将光源及纸张色彩属性与基于40名观察者心理物理学实验的1 000组书法展陈喜好数据进行关联性分析,进而从相关性分析、多元回归分析以及正态分布分析等多个统计学角度对传统书法作品展陈喜好的影响因素进行讨论。实验结果显示,传统书法作品展陈照明喜好与普通场景色彩喜好相比具有显著的特殊性,其喜好程度与明度对比、色相对比等色彩属性相关性较低,而主要受光源因素的影响。本研究的开展,将为当前传统书法作品的展陈照明工作提供有效的理论与方法参考,对于当前博物馆及美术馆的光源设计工作具有一定的指导意义。     

荧光粉封装方式对多芯片阵列LED封装效率的影响

针对荧光粉封装的多芯片LED,用Monte Carlo光线追迹的方法仿真光线在蓝光芯片和荧光粉中的传播,并分析了荧光粉封装方式对多芯片阵列LED封装效率的影响.结果表明:随着荧光粉层和芯片之间的距离增大,保型涂覆的LED封装效率先增加后减小,最大封装效率为59%;平面涂覆的LED在芯片间距为0.2mm、荧光粉层和芯片之间的距离为0.28mm时,封装效率为77.183%;荧光粉层的曲率半径对封装效率的影响较小.     

空心阴极元素灯光谱的空间分布测量方法

提出利用成像光谱仪研究空心阴极元素灯光谱空间分布的检测方法。自制了基于Offner成像系统的推扫式凸面光栅成像光谱仪,覆盖波长范围400~1 000 nm,视场角22°,光谱分辨率2~3 nm;利用该光谱仪第一次得到得到Hg元素灯光谱的空间分布,给出了不同波长下的空间图像和不同空间位置的光谱分布信息,具有较高的空间分辨率和光谱分辨率;并同时获取了不同工作电流条件下的元素灯高光谱数据,对比分析了处于不同工作状态下光谱空间分布的差异。这为空心阴极元素灯光谱的空间分布等性能研究提供了一个很好的工具,相关方法也可以用来研究其他类型的光源。     

Evaluation of solar spectral irradiance distribution using an index from a limited range of the solar spectrum

The output energy of photovoltaic (PV) modules under outdoor conditions is greatly influenced by the spectral irradiance distribution of the solar spectrum. To analyze this effect on PV modules, the spectral irradiance distribution, which is one-dimensional data, has to be represented by a zero-dimensional index. The average photon energy (APE) is an index for spectral irradiance distributions, which represents the average energy per photon in a spectrum. We have previously analyzed the uniqueness of the shape of the solar spectrum in the wavelength range of 350–1050 nm, and one corresponding value of APE showed a specific shape of spectral irradiance distribution. In this study, new indexes were calculated for a limited wavelength range of 350–750 nm and multiple bands of 450–500 nm and 800–850 nm of the solar spectrum for easy measurement and calculation. The result shows the uniqueness of new indexes to the shape of measured solar spectrum and the standard deviations were found to be quite small. This indicates that the new indexes are reasonable for representing the spectral irradiance distribution and its effect on PV performance.     

热释电探测器积分响应测试系统研究

为了实现对红外探测器积分响应的自动测量,配合虚拟仪器技术搭建了一套热释电红外探测器积分响应自动测试系统。利用双绞线将测试仪器与计算机连接,以LabVIEW为开发平台编写软件测试系统,遥控测量仪器,实现计算机自动采集和处理数据实时绘制曲线,对LT-020-H型热释电红外探测器在不同调制频率下的积分响应度进行了测试并分析。在500K的黑体辐射下,探测器积分响应度达到3.5×106V/W。通过对实验结果进行分析,得到了探测器响应、黑体辐射温度以及信号调制频率之间的关系。     

交流阻抗及功率因数测量中偏差的修正

介绍了在交流阻抗及功率因数测量中由测量仪表引起的偏差的修正方法.主要讨论了一级修正和精确修正两种方法,导出了计算复阻抗和功率因数的修正式.给出了测量日光灯电路的阻抗及功率因数的实例.由计算结果可以看出,精确修正后的结果与不做修正的结果之间存在较大的差异,说明在要求较精确测量的情况下,应该对测量结果进行修正.     

The beneficial effects of a p-type GaInN spacer layer on the efficiency of GaInN/GaN light-emitting diodes

Light-emitting diodes (LEDs) with a Mg-doped p-type Ga_1−xIn_xN (0 ≤ x ≤ 0.07) spacer layer located between an undoped GaN spacer layer and the electron blocking layer are investigated. The LEDs are found to have comparable peak efficiency but less efficiency droop when the crystal quality of the p-type Ga_1−xIn_xN spacer layer is well-controlled by lowering the growth temperature and by using a suitable In composition and Mg doping concentration. All LED samples with the p-type spacer layer show a smaller efficiency droop compared to a reference LED having an undoped GaN spacer. Among the sample sets investigated, an optical power enhancement of 12% at 111 A/cm² is obtained when inserting a 5 nm-thick p-type Ga_0.97In_0.03N spacer layer. The results support that carrier transport is the key factor in the efficiency droop observed in GaN-based LEDs.     

视场角和定位误差在光谱辐射亮度测量中的影响

为了减小不同光谱辐射计间瞄准区域差异带来的光谱辐射亮度不一致性,讨论了视场角及定位对于测量准确性的影响。通过建立太阳光白板和卤钨灯白板系统光路下的光谱辐射亮度测量模型,分析了不同几何光路视场区域平均辐射亮度与中心辐射亮度的差异。数值模拟表明,太阳光白板光路修正因子仅与视场角大小有关;卤钨灯白板光路修正因子随测量距离增大而减小,距离600 mm时8°和14°视场角的修正因子分别变为0.993 5和0.980 2。最后,实验验证了卤钨灯白板系统下角度误差和位移误差对光谱辐射亮度的影响。结果表明,修正因子对水平方向的角度误差和位移误差呈现非对称性,两侧差异高达2%。因此,依据视场角和几何定位可以对测量结果进行数据修正,有助于提升光谱辐射亮度测量不确定度水平。     

Influence of light source linewidth in differential-phase-shift quantum key distribution systems

Differential-phase-shift (DPS) quantum key distribution (QKD) is one of the QKD protocols, featuring simplicity for practical implementation. It uses a coherent pulse train whose phase should be stable at least within the pulse interval. This paper quantitatively investigates the phase stability required for DPS-QKD systems. The phase stability is characterized by the spectral linewidth of the light source. A theoretical model and experiments are presented, the results of which indicate that the linewidth should be, for example, less than 0.35% of the free-spectral-range of an asymmetric Mach-Zehnder interferometer in a receiver to achieve quantum bit error rate of less than 0.5% due to linewidth broadening of the light source.     

Effects of different correlations of partially coherent electromagnetic beam on three-dimensional spectral intensity distribution in the focal region

The effects of position-dependent correlations between the x- and y-components of the partially coherent incident electromagnetic beam on the spectral intensity distribution in the focal plane and along the z-axis of an optical imaging system with a high-numerical aperture are studied. The electromagnetic Gaussian Schell-model (GSM) beam is employed as an example to illustrate the analysis.     

Cryogenic radiometer based absolute spectral power responsivity calibration of integrating sphere radiometer to be used in power measurements at optical fiber communication wavelengths

This paper covers the absolute spectral power responsivity calibration of spectralon-coated Integrating Sphere Radiometer (ISR) equipped with 3 mm diameter InGaAs photodiode to be used as a transfer standard in fiber optic power measurements against Electrical Substitution Cryogenic Radiometer (ESCR) in Optics Laboratory of National Metrology Institute (TUBITAK UME) of Turkey. The initial uncertainty arising from the use of the Electrically Calibrated Pyroelectric Radiometer (ECPR) as a transfer standard in radiometric scale is 0.5% (k=2), which particularly comes from irregularity in the surface homogeneity of ECPR. In order to eliminate the ECPR step as well as its initial uncertainty contribution in fiber optic power measurements, the calibration application herein was carried out. Moreover power stabilization measurements of DFB laser sources at both 1309.1 nm and 1549.0 nm, the beam size determinations, and spectral analyses of these laser sources as well as spatial and angular dependence of spectral responsivities of the ISR were presented in this paper. The total expanded uncertainties were calculated as 0.283% and 0.315% in the determination of absolute spectral power responsivities of the ISR for 1309.1 nm and 1549.0 nm wavelengths respectively (k=2).     

基于相对光谱差异的非接触式LED结温测量方法

提出一种运用相对光谱的整体差异表征AlGaInP基LED结温的方法.首先使用光谱仪测量不同驱动电流、不同衬底温度下,不同颜色AlGaInP基LED的相对光谱,计算同一LED不同结温条件下相对光谱之间的差异,然后分析相对光谱差异与结温变化量之间的线性度,最后比较相对光谱差异法与峰值波长法测量的准确性.研究表明:相对光谱差异与LED结温变化成正比,相对光谱差异法的准确度和测量误差随光谱仪带宽的增大而增大.当光谱仪带宽为2nm时,其准确度优于采用带宽为1nm的峰值波长法;当带宽为5nm时,其准确度与带宽为1nm的峰值波长法相当.     

真空二极管大功率微波检波器设计

基于真空二极管设计了一种X波段大功率微波检波器,该检波器主要由真空二极管、BJ-100波导、调谐螺栓、低通滤波器和直流电源组成,其工作频率可根据需要在8.6~9.8 GHz范围内调谐。重点阐述该型大功率微波检波器的结构设计、实验室标定及辐射场测量实验结果,研究了不同脉宽和不同灯丝电压与检波特性的依赖关系。实验结果表明：该型检波器具有承受微波脉冲功率高（大于7 kW）、响应快（响应时间小于2.0 ns）、动态范围大、输出信号幅度高（可达数十V）、不需要同步信号等特点,适用于在高功率微波干扰环境下的单次和高重复频率脉冲功率测量。