套管辅助法测量异型预制棒折射率分布

基于光束扫描法的光纤预制棒折射率测试仪主要适用于直径和长度在一定范围内的圆柱形样品折射率分布的测试。提出一种套管辅助法可实现更短长度、更细直径和变直径样品的折射率测试。该方法将待测样品居中放置于一个尺寸符合测试要求的圆柱形套管内,并在套管内注入折射率匹配油,使其没过待测样品后按常规步骤进行测试。对比实验结果表明,套管辅助法与直接测量法的偏差与仪器的测量误差相当。采用套管法,获得了预制棒拉丝终止后变径区不同位置折射率的径向分布,可为拉丝过程的研究提供参考。     

人工水晶钻石白度的检测方法

利用阿贝折射仪检测了人工水晶钻石的折射率，介绍了以不同固体的折射率为标准进行人工水晶钻石的白度分析的方法．     

Liquid refractometry: an approach for a continuous measurement

A method is described for obtaining an accurate real-time measurement of the refractive index of liquids. It is based on a modification of the Pulfrich refractometer. The optical arrangement is suitable for in-line industrial applications where a continuous measurement is required. Some experimental results are presented which confirm the feasibility of the method.     

用光纤测量液体的折射率

本文提出了用光纤测量液体折射率的方法。测量值的范围不受限制，弥补了阿贝折射仪的不足之处。并可使学生对光纤有所了解。     

High resolution optical refractometer for dispersion measurement in UV-NIR range

A high resolution optical refractometer for dispersion measurement in the UV-NIR range is described. Using this refractometer, refractive index of a range of liquid samples, such as aqueous solutions of sugars, salts and alcohols, was measured as a function of wavelength in the range from 300 nm to 920 nm with accuracy better than 10 ^{- 5}. So accurate results can be used for improvement of resolution of OCT measurements conducted in biological samples.     

用光纤杨氏干涉测量液体的折射率

介绍一种用光纤扬氏干涉测量液体折射率方法。测量值的范围不受限制,弥补了阿贝折射仪的不足。方法简单、直观,测量量少,并可使学生对光纤有所了解。     

Optical refractometer based on an asymmetrical twin-core fiber Michelson interferometer

We report and demonstrate an optical refractometer based on a compact fiber Michelson interferometer. The Michelson interferometer is composed of an asymmetrical twin-core fiber containing a central core and a side core. By chemically etching a segment of the twin-core fiber until the side core is exposed, the effective index of the side core in the etched region is sensitive to the environmental refractive index, which leads to a shift of the transmission spectrum of the Michelson interferometer. The experimental results show that such a device has a refractive index resolution of more than 800 nm/refractive index unit in the range of 1.34-1.37.     

Full-field imaging-based instantaneous hyperspectral absolute refractive index measurement

Multispectral refractometers typically measure refractive index (RI) at discrete monochromatic wavelengths via a serial process. We report on the demonstration of a white light full-field imaging-based refractometer capable of instantaneous multispectral measurement of absolute RI of clear liquid-gel samples across the entire visible light spectrum. The broad optical bandwidth refractometer is capable of hyperspectral measurement of RI in the range 1.30-1.70 between 400 and 700 nm with a maximum error of 0.0036 units (0.24% of actual) at 414 nm for an η=1.50 sample. We present system design and calibration method details as well as results from a system validation sample.     

Development of an optical refractometer by analysis of one-dimensional photonic bandgap structures with defects

A theoretical analysis of an optical fiber photonic-bandgap-based refractometer is presented. The design is based on a quarter-wave reflector with one defect. By modifying both the real and the imaginary parts of the index of refraction of the defects we begin to change either the frequency or the amplitude of the localized optical mode. So we could fabricate a specific optical fiber refractometer by combining all the variables: index of refractive index of the defects and the rest of layers, thickness of the defect, number of layers, etc. to yield a large set of design possibilities, for example, detecting wider or thinner ranges of refractive indices, or controlling the detection accuracy. Some rules for the practical implementation of the refractometer are given.     

反射式光纤表面等离子体波共振传感器特性研究

研究了一种基于表面等离子体波共振(SPR)光谱分析的折射率检测新方法。研究发现,表面等离子体波共振效应光谱特征的折射率灵敏度会随着液体性质变化而发生改变。根据折射率测量范围不同,分别选择共振波长和共振强度作为检测参量,实现理论折射率分辨力达到10~(-5)数量级以上。在理论分析和实验基础上,设计出一种基于共振光强检测的终端反射式光纤表面等离子体波共振效应传感系统,采用将传感信号和基准光信号的比值作为液体折射率变化的度量值。在1．3325～1．3991的折射率测量范围内,度量值与折射率之间呈现单调递减关系,线性相关系数为0．9983。通过定义耦合系数,还可实现对表面等离子体波共振效应效应强弱和变化趋势的评估。     

高精度V棱镜折射仪光机结构设计

针对传统V棱镜折射仪采用光学度盘,目视对准方式无法满足现代光学玻璃生产线以及高精度折射率测量的需求。提出一种新型的高精度基于CCD 机器视觉对准的V棱镜折射仪的总体设计方案,并对准直光管、传动机构、锁紧和微调机构以及轴角编码测角机构等主要组成部分进行了光机结构设计。在考虑空气折射率影响因素的修正公式的基础上,分析了仪器的检测误差。实验结果表明:其折射率检测精度可达 310-6,满足了高精度V棱镜折射仪的技术指标要求。     

圆盘型液体线性光电折射率计

提出一种具有线性响应的圆盘型液体光电折射率计，光线在圆盘内的多次反射显著地消除了非全内反射的影响，有效地改善了测量线性度，这种圆盘型光电折射率计甚至可对非平行入射光束仍保持相当好的线性度。     

用阿贝折射仪测量单色光折射率

本文介绍了用阿贝折射仪测量单色光折射率的原理及方法。     

利用彩虹强度角谱分布对圆柱直径的测量

采用ＣＣＤ线阵的散射光强角分布测量系统,测量了水、酒精液柱、光纤的彩虹角分布。根据严格米氏理论,数值研究了大尺寸参数圆柱的彩虹现象,获得与实验相吻合的数值结果。讨论了几何光学和艾里理论局限性,将米氏理论和几何光学结合,对彩虹现象给予了更为合理的解释。利用第一级彩虹角反演折射率,以及将彩虹强度导数角分布进行快速傅里叶变换获得了角谱反演圆柱粒子的直径。并讨论了利用角谱反演粒子折射率和直径的精度。     

Single-mode fibre coupler as refractometer sensor

We report a simple, non-intrusive fibre-optic refractometer sensor for measuring the refractive index of liquid and optically transparent solid medium. Sensing principle of the proposed sensor is based on monitoring the back-reflected light signal through the second input port of a 2 × 1 single-mode fibre coupler when light signal from the output port is focussed at the interface of air and a liquid or solid medium and back-reflected exactly along the same path. Depending on the refractive index of the medium, the amount of back-reflected intensity would vary and in the present work we exploit this principle to measure the refractive index of an optically transparent medium. Variation of refractive index as small as 0.001 RIU can be measured with our proposed sensor.     

圆盘式折射计中的光线分析

本文对作者提出的圆盘式折射率计里的光线,特别是非平行光线的传输问题进行了详尽的分析.分析及计算机计算表明,圆盘式折射率计的线性度甚至可对非平行光线仍良好保持.圆盘内光线的多次反射克服了非全内反射的影响,使得输出线性度仍然得以保持.有关参数设计及改进精度的讨论亦在本文作了讨论.     

Non-intrusive refractometer sensor

An experimental realization of a simple non-intrusive refractometer sensor is demonstrated in this communication. The working principle of the sensor is based on intensity modulation of the back-reflected light when output light from an optical fibre end focusses onto air-medium interface. The change in the refractive index of the medium affects the reflectance of the incident light signal and thus modulates the back-reflected signal. Refractive index variation as small as 0.002 RIU can be measured using the present technique. The advantages of the technique are its simplicity, cost efficiency and usefulness in monitoring refractive indices of acidic solutions.     

Microstructured fiber based plasmonic index sensor with optimized accuracy and calibration relation in large dynamic range

A novel surface plasmon resonance photonic sensor is proposed using an index-guided microstructured fiber with an analyte channel introduced into the central core. Compared with the previous designs of porous fiber core, variation of the signal amplitude with exterior refractive index is demonstrated to be contrary to that of the sensitivity in the proposed fiber, contributing to optimized detecting accuracy over a large refractive index range of 1.33 to 1.42. By carefully choosing the central channel size, the analyte-filled core can achieve narrower resonance spectral width and higher signal to noise ratio (SNR) than the air-filled core. Sensor responses are also studied in this paper based on two spectral interrogation methods, including monitoring single resonance shift and measuring change in the resonance separation. For both methods, response linearity has been improved considerably through partially filling the core with analyte. The maximal sensitivity reaches 10^− 6 refractive index unit (RIU). The linear sensing performance along with the broad measurement range is very promising in the application of the proposed sensor as sensitive refractometer.     

Reflective fiber-optic refractometer based on a thin-core fiber tailored Bragg grating reflection

A novel reflective refractometer based on a thin-core fiber (TCF) sandwiched between a leading single-mode fiber (SMF) and a fiber Bragg grating (FBG) imprinted SMF stub was demonstrated. The reflection from the fiber stub occurs in two well-defined wavelength bands, corresponding to the Bragg core mode and cladding modes. The TCF section functions as a tailorable bridge between the FBG core mode reflection and the surrounding refractive index (SRI). Linear response with enhanced sensitivity of 133.26 dB/refractive index unit for temperature-immune SRI measurement within the biologically desirable sensing range of 1.33-1.41 has been achieved via cost-effective power detection.     

Prism-coupled multimode waveguide refractometer

A new refractometer has been developed based on changes in the effective refractive index (RI) of the highest-order TE (or TM) mode in a prism-coupled multimode planar waveguide induced by interaction between an evanescent field and a liquid sample. The waveguide was a 100-mu;m -thick quartz plate fixed on a poly(methyl methacrylate) support containing a flow cell. A pair of prism couplers contacted the quartz plate in the flow-cell region. Such an optical sensor can detect the RI of liquid in a wide range by monitoring the resonant angle of the highest-order mode that changes order number with changes in the sample's RI. When a highest-order mode corresponding to a given RI range is used as the sensor probe, a slight RI change in this range can be detected by measurement of the output light intensity. With this method the sensor was demonstrated to have a resolution of 3x10(-5) for the RI of an aqueous solution. Combining this result with theoretical calculation indicates that the sensor can detect a 0.5-nm-thick monolayer adsorbed from an aqueous solution. Therefore, the sensor is suitable for real-time detection of biomolecular interactions.