Refracted Near-Field Measurements of Refractive Index and Geometry of Silica-on-Silicon Integrated Optical Waveguides

The standard refracted near-field technique for measuring the refractive-index profile of optical fibers cannot be directly used for silica-on-silicon integrated optical waveguides because of the opacity of silicon. A modified method is thus presented to characterize this kind of waveguide. The resolution it gives, both spatially and in the refracted index, is practically as good as that obtained with the standard technique for measuring optical fibers.     

The Savart Interferometer Modified for High Sensitivity in Measurements of Refractive Index Gradients

Interferograms are produced with the two-plate version of the Savart interferometer by a double exposure technique. By rotating one of the Savart plates 180°, and with the aid of a rotatable mask, each of the two exposures is made to form one-half of the resulting picture. If the object being investigated contains a time-variant refractive index gradient, the interferograms are made up of two fringe systems that are displaced in opposite directions from one picture to the next. Their relative positions are a measure of the gradient, and the technique gives a gain in sensitivity by a factor two, compared with other single pass instruments. The technique has been tested for thermal diffusion measurements. The theory given here is confirmed by the experiments.     

Measurements of Density and Refractive Index of Soybean Oil + Short Aliphatic Alcohols

Densities and refractive indices of binary mixtures containing soybean oil + (methanol, ethanol, 1-propanol, 2-propanol, or 1-butanol) have been measured from 283.15 to 298.15 K at atmospheric pressure, over the complete homogeneous composition range. Derived properties, such as excess molar volumes, partial excess molar volumes, and excess isobaric compressibilities, have been determined. Values of physical properties were compared with the results obtained by different prediction methods; the results were analyzed according to the non-ideality and large differences of molecular characteristics of the compounds included in this study.     

高聚物折射率的测量

本文提出两种测量高聚物折射率的简单方法，其一是基于洛仑兹－洛仑茨公式导出混合物质折射率公式，并由此发展成一种折射率的测量方法；其二是用溶液制膜法将高聚物制成薄膜，从而实现折射率的测量．两种测量都可用阿贝折射仪完成．     

特高折射率玻璃微珠的制备及折射率测量方法

采用高温吹制工艺制备出直径３０～５５μｍ、特高折射率玻璃微珠。以近轴光线成像的理论为基础，提出了用光学显微镜测量玻璃微珠折射率的简便方法。测得所制备玻璃微珠的平均折射率为２．４７；分析和讨论了测量方法的误差和实用性。     

一种测量折射率的新方法

提出一种新的折射率测量方法。利用倾斜平行平板会引起出射光束位置平移的测量原理。同线阵ＣＣＤ探测产生了位移的光束，通过计算程序实时算出样品折射率。为了证实这种方法的可行性。本文作者建立了一个由Ｈｅ－Ｎｅ激光器、透镜组、ＣＣＤ传感器和单片机组成的实验系统，具体研制了硬件和软件，对厚度ｔ＝１５ｍｍ，θ４５°＝的Ｋ９玻璃进行了实际折射率测量。折射率在１．４－１．９之间时，该方法能达到小数点后四位以上的测量     

Non-ambiguous Evanescent-wave Fibre Refractive Index and Temperature Sensor

The dependence of the leakage of the LP₀₁ mode of a polished single-mode fibre section on the refractive index of an external medium provides non-ambiguous intensity modulation of the guided wave and a single-point in situ calibration of a sensor based on this refractive index, or temperature, transducing mechanism. Refractive index and temperature resolution of 10^m4 and 0·1°, has been obtained over an adjustable range of 0·02 and 80°, respectively.     

高折射率光学树脂的结构设计

从分子设计的基本原理入手,总结了分子结构时树脂折射率和色散的影响,指出含有脂环、硫、溴、碘、磷、砜基及部分重金属元素的树脂既具有较高的折射率又具有较低的色散,并按树脂结构与官能团特征对高折射率材料进行分类,分析了各类树脂的优缺点.     

圆柱微波谐振法测量氩气折射率

氩气等单原子气体的折射率,是检验量子力学从头算理论的重要参数。基于圆柱微波谐振法,精确测量了234～303 K、 0～750 kPa范围内氩气的折射率。测量了圆柱腔内不同压力下4种横磁 (TM) 模式的微波谐振频率,对谐振频率进行非理想因素修正后,结合真空下的微波谐振频率获得氩气的折射率。圆柱腔内微波谐振频率测量不确定度为2×10^-8,4种模式获得的氩气折射率的相对标准偏差小于1×10^-6。通过氩气的折射率计算获得了氩气的第一介电维里系数,与国际上已发表的结果具有良好的一致性。基于建立的实验系统,后续可开展其他气体的折射率测量。     

Defective kernel detection using a linear colour CCD

Abstract

This study was aimed at detecting defective wheat (Triticum durum Desf) with a machine vision system of linear colour charge-coupled device. One thousand one hundred and sixty-nine images were captured for sound kernels, 710 for black germ kernels and 627 for broken kernels. A software package was developed to extract various morphological, colour and texture features from the images captured. Then the experimental data were subjected to multivariate analysis. Principal component analysis was employed to differentiate samples from different categories. Partial least square discriminant analysis and venetian blinds cross-validation were used to develop classification models. The best detection accuracies of samples were 92·7, 88·0 and 89·6% for black germ kernels, broken kernels and sound kernels. The results have proved that it is feasible and effective to employ partial least square discriminant analysis for feature selection and defective kernel detection.     

镀制工艺对TiO2光学膜层折射率影响研究

研究分析了基底温度、沉积速率、氧气分压、离子束辅助沉积等工艺参数和条件对TiO2膜层折射率的影响.研究表明,随着基底温度升高,TiO2光学膜层折射率呈上升趋势;随着沉积速率提高,TiO2膜层折射率存在极值;采用离子束辅助沉积工艺,可以有效提高TiO2膜层折射率值,所制备的TiO2膜为非晶态结构,具有较高的折射率和较小的光学损耗.     

负折射率材料可控效应及结构设计

控制电磁波的传播方向,甚至控制包括光波在内的波的传播方向,是一个充满前景的研究方向.本文对可控负折射率材料进行了研究,利用折射率的变化则可以实现波方向上的可控.根据对双金属环阵列结构产生负磁导率特性的分析,研究了该结构金属环局部开口状态至局部闭合状态导致的磁导率及最后导致折射率的变化,发现开闭口出现的不同特性,设计了双金属环局部闭合状态阵列可控结构的方案.分别对开口金属环阵列和局部闭合金属环阵列进行磁导率及它们与金属带组合结构折射率的实验,与理论结果相比较,并且对本文所设计的可控负折射率阵列结构进行了验证.最终结果证明,通过设计的这个结构,可以实现某一微波波段波传播的两个方向的控制,同时本文的实验结论也证明了利用折射率的改变来控制波的传输方向是可行的.应用合理的结构,通过操控电场,可以实现在波在方向上的改变.这对于研究和工程应用都有着可行的巨大潜力.     

折射率可调的纳米彩色薄膜的制备研究

采用溶胶-凝胶技术,以正硅酸乙酯和钛酸丁酯为有机醇盐前驱体,乙醇、生物染色剂为主要原料,利用提拉法制备出折射率可调的纳米复合彩色薄膜.经测试研究表明,薄膜的折射率随TiO2含量的增加以及热处理温度的升高而逐渐增大.通过调整溶胶的组分及热处理温度,可实现纳米复合彩色薄膜的折射率在1.51～2.25之间连续可调.而且生物染色剂无毒无害,在高温下能自行分解,加热到一定温度时可恢复到无色状态,是环保型彩色薄膜.     

Infrared Refractive Index and Extinction Coefficient of Polyimide Films

We have measured the transmittance of several polyimide (C₂₂H₁₀N₂O₄) films at wave numbers from 6000 to 500 cm^–1 (wavelengths from 1.67 to 20 m) using a Fourier-transform infrared (FT-IR) spectrometer. The free-standing polyimide films are made by spin coating and thermal curing processes. The thickness of the films ranges from 0.1 to 4 m. In the nonabsorbing region from 6000 to 4000 cm^–1, the minimum transmittance caused by interference is used to obtain the refractive index for film thicknesses greater than 1 m. The film thicknesses are determined by fitting the spectral transmittance using the refractive index. Molecular absorption strongly reduces the transmittance at wave numbers from 2000 to 500 cm^–1. The optical constants, i.e., the refractive index and the extinction coefficient, are determined from the measured transmittance for several films of different thickness using a least-squares method. A Lorentzian oscillator model is also developed, which in general agrees well with the measured transmittance at wave numbers from 6000 to 500 cm^–1. This study will facilitate the application of polyimide films in the fabrication of infrared filters and other optoelectronic applications. The methods presented in this paper can be used to determine the optical constants of other types of thin-film materials.     

Interline Transfer CCD Camera for Gated Broadband Coherent Anti-Stokes Raman-Scattering Measurements

Use of an interline transfer CCD camera for the acquisition of broadband coherent anti-Stokes Raman-scattering (CARS) spectra is demonstrated. The interline transfer CCD has alternating columns of imaging and storage pixels that allow one to acquire two successive images by shifting the first image in the storage pixels and immediately acquiring the second image. We have used this dual-image mode for gated CARS measurements by acquiring a CARS spectral image and shifting it rapidly from the imaging pixel columns to the storage pixel columns. We have demonstrated the use of this dual-image mode for gated single-laser-shot measurement of hydrogen and nitrogen CARS spectra at room temperature and in atmospheric pressure flames. The performance of the interline transfer CCD for these CARS measurements is compared directly with the performance of a back-illuminated unintensified CCD camera.