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A method for simultaneous measurement of geometric thickness and refractive index of an optical wafer is presented. By using a fiber optic Mach–Zehnder interferometer (MZI) with a free space, the transmission spectrum of a MZI for the optical wafer at different incidence angle is interrogated, and the geometric thickness and the refractive index of the optical wafer are measured simultaneously. With the transmission spectrum, we can obtain a clear interferogram with a high visibility no matter how small the measurement range of the refractive index. Therefore the proposed technique possesses a broad measurement range and low cost. The experimental results show that the maximum errors of the geometric thickness and the refractive index are only 0.007?mm and 0.008, respectively, and that a broad measurement from 1.316 to 3.503 can be achieved. 相似文献
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A superimposed long period fiber grating design proposed for refractive index sensing is shown to be superior to conventional dual resonance and turnaround point gratings and can operate at any chosen wavelength region by appropriate design. Numerical simulations carried out on standard single mode fibers show that such sensors can operate over a wide refractive index range (1.33–1.42) exhibiting a high sensitivity of ~500–1545?nm/RIU, yielding ~10?6–10?7 refractive index change corresponding to the resonance relative shift of 1?pm with potential applications to chemical and biological industries. The proposed scheme can also discriminate between refractive index and temperature changes. 相似文献
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A kind of compact fibre-optic sensor based on no-core fibre (NCF) cascaded with a strong coupling long-period fibre grating (LPFG) is proposed and experimentally demonstrated. The sensing mechanism is based on the Mach–Zehnder-like interference between the core fundamental mode and cladding mode of the fibre structure. The NCF and LPFG are used as the mode exciter and combiner, respectively. Due to the particular properties of the strong coupling LPFG, the measurements of refractive index (RI) and temperature with high sensitivity are realized by monitoring the transmission spectrum with intensity and wavelength interrogation techniques, respectively. The achieved RI sensitivity reaches ?580.269 dB/RIU in the range of 1.436–1.454 and the temperature sensitivity reaches 27.2 pm/°C. 相似文献
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H. J. Achtermann T. K. Bose H. Rögener J. M. St-Arnaud 《International Journal of Thermophysics》1986,7(3):709-720
We show that the absolute determination of the refractive index, when combined with an expansion technique for obtaining the higher-order coefficients of the Lorentz-Lorenz expansion, leads to precise values of density. A grating interferometer has been developed for the refractive index measurements as a function of pressure. The advantage of a grating interferometer is that it performs a reversible counting and generates a DC compensated signal from the interference fringes. The pressure is also measured with an interferometer, previously calibrated with an oil-type precision piston gauge. For the precise determination of the compressibility factor, the absolute measurement of the refractive index is combined with the differential technique to determine the refractivity virial coefficients of the Lorentz-Lorenz expansion. The compressibility factors of methane, nitrogen, and their mixtures have been determined at 323.15 K for pressures up to 335 bar. The optical method for the determination of the compressibility factor not only is shown to be precise, but also has the ability to produce numerous experimental points in a short time as compared to other methods.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A. 相似文献
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电子液位控制系统可以很好地实现对液位的控制,保证系统的平稳运行并提高效率。但是电子液位系统中的关键部件,如液位传感器,依然面临某些问题,例如液位传感器和执行机构的准确性/控制精度以及可维护性问题。本文尝试采用新型液位传感技术——导向雷达液位测试技术配合电动阀作为执行机构,确保工业制冷系统安全运行可靠的同时,提高系统效率、增强系统的可维护性。 相似文献
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使用德国Triotics公司生产的SpectroMaster HR UV-VIS-IR型折射率测量设备,对FK5玻璃块的e、d、g、F′和C′谱线的折射率值进行高准确度测量,并修正至标准环境条件下的折射率值。用得到的折射率值进行曲线拟合,验证Cauchy色散公式和Sellmeier色散公式。 相似文献
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Abstract Particle tracking velocimetry is applied to flow inside a porous column at Reynolds number Re = 28. The column is composed of refractive‐index‐matched solid and liquid materials, allowing seeding particles to be tracked in a laser‐illuminated axial slice. To complement earlier results acquired for 7 mm spheres, we conduct new experiments with larger 12 mm spheres. By improving the image acquisition and analysis, we are able to process the new experiments using fully automated algorithms instead of manual tracking. As a result, greater vector yields, more accurate velocity data, and a more complete spatial coverage are achieved. 相似文献
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本文介绍了双波长激光量块干涉仪中使用的温度、湿度和气压传感器,描述了其工作原理、设计方案、测量不确定度以及校准方法。这些传感器同样可用于其他高准确度长度测量的激光干涉系统中。 相似文献
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Low-coherence interferometer system for the simultaneous measurement of refractive index and thickness 总被引:1,自引:0,他引:1
We have developed a low-coherence interferometer system used for the simultaneous measurement of refractive index n and thickness t of transparent plates. Both the phase index n(p) and group index n(g) can be determined automatically in a wide thickness range of from 10 microm to a few millimeters. Two unique techniques are presented to measure n(p), n(g), and t simultaneously. One allows us to determine n(p), n(g), and t accurately by using a special sample holder, in which the measurement accuracy is 0.3% for the thickness t above 0.1 mm. In the other technique the chromatic dispersion delta n of index is approximately expressed as a function of (n(p) - 1) on the basis of measured values of n(p) and n(g) for a variety of materials, and then the simultaneous measurement is performed with a normal sample holder. In addition, a measurement accuracy of less than 1% is achieved even when the sample is as thin as 20 microm. The measurement time is also 3 min or more. 相似文献
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Composites with enhanced refractive index have been synthesised through a sol–gel process. A refractive index of approximately 1.70 has been achieved at a concentration of 75 wt% TiO2. The refractive index increases with the concentration of TiO2. The influence of the concentration of TiO2 on the mechanical properties has been studied. The potential application of these materials in photonics area has been demonstrated by fabricating multi-layer spherical voids in them through a femtosecond laser-driven micro-explosion method. 相似文献
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The structure, working principle, and basic metrological characteristics are given for the State primary standard for a unit of refractive index GÉT 138-2003.Translated from Izmeritelnaya Tekhnika, No. 11, pp. 3–6, November, 2004. 相似文献
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我们设计并制作了一种基于Mach-Zehnder干涉的高灵敏折射率传感器,其结构由两个光纤纤芯偏移的熔接结经包层腐蚀后组成。首先,利用商用的光纤熔接机在单模光纤上制作两个光纤纤芯偏移的熔接结;然后,将光纤化学腐蚀获得细薄的光纤包层,则光纤倏逝场与周围介质强烈相互作用,即制作出Mach-Zehnder干涉型高灵敏折射率传感器。实验结果表明,制作的长度为10 mm、直径为13.2μm的Mach-Zehnder干涉型折射率传感器,在折射率1.333~1.3685和1.3685~1.386范围内,其传感灵敏度分别高达1288.05和2118.26 nm/RIU。该传感器具有高灵敏度、结构紧凑、制作简单和低成本的优势。 相似文献