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Air, liquid and solid sample interferometric gaps of the same thickness and simultaneously enclosed in a wedge interferometer are used to produce fringes of equal chromatic order. A mica sample of dimensions 2×5 mm2 and an immersion liquid of the same refractive index are used. A single shot interferogram containing fringes in the three gaps is sufficient to deduce the needed experimental data. Locations of fringe maxima are introduced in a numerical procedure to retrieve the sample and liquid refractive indices across the visible spectrum. The numerical procedure is based on a simple dispersion function of wavelength and wavenumber. A modified two-term Sellmeier dispersion formula has been used for fitting the experimental data and deducing the needed dispersion parameters. 相似文献
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S. Y. El-Zaiat 《Optics & Laser Technology》2001,33(2)
Fringes of equal chromatic order are produced in air, immersion liquid and mica sample interferometric gaps. The three gaps are of the same thickness and simultaneously enclosed in a wedge interferometer. A single-shot interferogram contains fringes in the three gaps is sufficient to deduce the needed experimental data. A non-numerical procedure is used for determining the refractive indices of the immersion liquid and mica sample across the visible spectrum. There is no need for any numerical fitting stage nor for the application of any theoretical model concerning the dispersion behavior of the sample under test. A modified two-term Sellmeier dispersion formula has been used for fitting the experimental data and deducing the needed dispersion parameters. 相似文献
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Fringes of equal chromatic order in transmission across a thin liquid or a thin solid sample inside a wedge interferometer, followed with a grating spectrograph, are produced. A single-shot interferogram of the air and sample regions is recorded. Locations of fringes maxima in the air region are fitted in a numerical procedure based on Cauchy's dispersion function. Then it is used for measuring the interferometric gap thickness. The order of interference in the sample region is represented by a third-order polynomial in the wavenumber for deducing the sample group refractive index. An error analysis of the measured group refractive index is given. The method is applied for measuring the group refractive index of water and mica samples across the visible spectrum. The method measures both the sample thickness and its group refractive index. It is static with no moving parts and suitable for thin liquid or solid samples without immersion liquids. 相似文献
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A new application of the Paul wavelet algorithm was presented to determine the refractive index dispersion of a dielectric film from transmittance spectrum in the visible and near infrared region. The developed algorithm was tested by simulated data and experimentally applied to a sample of mica. The obtained refractive index dispersion determined by the Paul wavelet algorithm was compared with the refractive index values determined by the envelope and fringe counting methods, and also with the established result. It was shown that the degree of the Paul wavelet has a major effect on the outcome of a refractive index determination. The noise immunity of the presented method was shown by the simulation study. 相似文献
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A spectral-domain technique based on tandem interferometry is used for measuring the group dispersion of optical samples over a wide wavelength range. The technique utilizes a tandem configuration of a Michelson interferometer and an unbalanced Mach–Zehnder interferometer with a sample inserted into its test arm. First, the theoretical background of the technique is presented and then experiments with individual interferometers and their tandem configuration are specified. In all the experiments the spectral signals are recorded to measure the equalization wavelength as a function of the path length difference, or equivalently the group dispersion. We measure the group refractive index as a function of wavelength for a glass sample of known thickness and for a quartz crystal as well. 相似文献
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We present a simple method to measure the refractive index dispersion over a broad wavelength range (0.6-1.6 μm). In a first step, the optical group indices are obtained by measuring the time-retardation of tunable 150 fs laser pulses within a sample relative to air. The refractive index dispersion is then calculated using a Sellmeier equation that describes the measured group index dispersion. We show that our experimental data agree with previously published results to within 2 × 10−4 for a 3 mm thick sample of fused silica and to within 3 × 10−3 for the index n1 of a 2 mm thick crystal of the highly dispersive and anisotropic organic crystal 4-N,N-dimethylamino-4′-N′-methyl stilbazolium tosylate (DAST). 相似文献
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The chromatic dispersion for conventional and Er-doped fibers using the refractive index approximation is examined. A first, analytical method for investigation of dispersion in step index triple clad optical fiber is used. To design of zero-dispersion shifted fiber for optical communication purpose manipulation of the refractive index and radius of the core are considered. We show that in presence of the Si-NC-Er ions, zero-dispersion wavelength is displaced and the dispersion quantity is increased. In this work, we try to optimize system parameters to obtain minimum dispersion and dispersion shifted fiber with control of the doping levels of Er ions and Si-NC as well as doping profiles. For especial case, we assumed the Gaussian inhomogeneous core refractive index for zero-dispersion wavelength and dispersion managements. 相似文献
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全息干板膜的厚度是全息干板的重要参数之一。使用迈克尔逊干涉仪和白光光源对2种全息干板膜厚度进行测量,并对测量结果误差进行分析,给出了测量误差与膜厚及折射率之间的关系以及此方法的适用范围。研究结果表明:在膜厚从8μm增至41μm的过程中,测量结果的绝对误差≤2μm且变化很小,相对误差则从14.1%降到了2.2%。随着膜厚的增加,相对误差明显降低;折射率n也参与了误差传递,其值与测量误差呈类似反比关系;当n值在1.5附近时,为保证测量的准确性,所测膜厚≥40μm。最后指出,迈克尔逊干涉仪在测量全息干板膜等较厚的薄膜时,具有测量范围大,结果较准确等优点。 相似文献
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Multiple-beam interference fringes of equal chromatic order are produced in air and liquid sample interferometric gaps. The two gaps are of the same thickness and simultaneously enclosed in a wedge interferometer. A single shot interferogram containing fringes in the two gaps is sufficient to deduce the needed experimental data. Locations of the fringe maxima, in the two gaps, are introduced in a non-numerical procedure for determining the gap thickness and the liquid-phase refractive indices across the visible spectrum. The method has been used for measuring the phase refractive indices of human blood-serum, saliva, sweat, urine and water liquids. A third-order polynomial dispersion relation is applied for fitting the measured phase indices. Group refractive indices have been derived and fitted to the same dispersion formula. 相似文献
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A new dielectric slab waveguide with a left-handed material (LHM) cover and substrate is proposed. The dispersion relations
and normalized effective thickness of the asymmetric LHM slab waveguide are investigated, in view of the normalized parameters.
A number of unusual properties are found, for example, the fundamental and first-order modes do not exist and higher-order
modes have double degeneracy. The propagation modes are absent at the low normalized frequency, and the cutoff frequencies
of some LHM slab waveguide modes decrease with increase in the asymmetry measure. Unlike traditional slab waveguides, the
V –H curves of the LHM slab waveguides are in one-to-one correspondence. Both TE and TM modes are discussed; in addition, the
dispersion relations and normalized effective thicknesses of the TM modes are discussed in detail, when the difference in
refractive indices of the film and the substrate is small. The results show that the region of mode coexistence taking place
near the cutoff frequency becomes narrower with increase in the difference in refractive indices of the film and the substrate.
The influence of this difference on the normalized effective thickness curves is different, and becomes smaller and smaller
with increase in the value of the asymmetry measure, if different values of the refractive indices are employed. 相似文献
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目前半导体锗在吸收边附近(1550 nm)的压力-折射率系数在实验和理论上并未研究清楚.本文通过测量在不同压力下镀在光纤端面的高结晶度锗薄膜的反射率,来计算得到锗在吸收边附近的压力-折射率系数.本文的实验结果显示,锗在吸收边附近出现反常色散现象,即折射率随能量变化呈正相关,并且其压力-折射率系数出现反常,为正值,这是由于多晶结构中的激子吸收所引起.通过引入描述激子色散的临界点模型,得到锗在吸收边附近的反常色散范围和压力-折射率系数呈正值的范围.本文的结果将有助于基于锗薄膜的通信C波段光学器件的研究. 相似文献
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In this paper, we describe a novel waveguide surface plasmon resonance sensing structure, which consists of a symmetric structure and a planar waveguide. The core component is the symmetric structure of the metal layer, tested sample, and metal layer. The refractive index matching condition of this structure can be adjusted through the thickness of the sample. The planar waveguide is used to excite the surface plasmon wave, and then the parameters are tested and analyzed. The surface plasmon wave is excited when glycerin solutions with concentrations of 0%–70% are used to detect at thicknesses of 300 and 500 nm. The problem that the effective refractive index of the ion exchange planar waveguide is large and using this index to excite the surface plasmon wave between the metal and dielectric for detection is difficult to achieve can be countered by appropriately choosing the thickness of the dielectric in order to be able to measure different refractive indices. 相似文献
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常用的测量折射率的方法如偏向角法、自准直法、临界角法、 V棱镜法等,这些方法通常需特制三棱镜与待测件。待测样品不一致且过程复杂,测试定标周期长,难于自动化。为了保证待测材料的完整及实现自动化测量,进行了基于平行平板的折射率非接触测量的尝试。运用该方法进行折射率的测量,不需特制三棱镜并且待测件与待测样品一致。分析表明,通过选择合适的测量角度,该方法旋转角度精度为a=0.003(即10),导轨精度为L=0.000 8 mm,平行平板厚度测量精度为d=0.001 mm。 相似文献