共查询到20条相似文献,搜索用时 15 毫秒
1.
A new kind of interference fringes, fringes of equal tangential inclination by curvature-induced birefringence, is presented. These are two-beam interference fringes produced by bending a thin sheet of birefringent material into a part of an exact cylinder such that the curvature is constant. Due to this curvature there is a uniform birefringence being induced. The change in birefringence induced by applying different radii of curvatures to a Fortepan sheet is measured. The stored (fixed) or natural birefringence of this sheet is deduced. 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 novel low power chromatic dispersion monitoring technique employing SOA spectral shift 总被引:2,自引:0,他引:2
A novel approach for online chromatic dispersion monitoring by use of the spectral shift in the semiconductor optical amplifier (SOA) is proposed and experimentally demonstrated. Power on the long-wavelength side of the signal through the SOA is extracted for measuring the dispersion characteristics. Keeping a constant input power of 0 dBm, the experimental result shows that the ratio of the filtered power to the total power decreased by 10 dB when the introduced dispersion reaches ±700 ps/nm. 相似文献
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Feroza Begum Yoshinori Namihira S. M. Abdur Razzak Shubi F. Kaijage Nguyen H. Hai Kazuya Miyagi Hiroki Higa Nianyu Zou 《Optical Review》2009,16(2):54-58
This research presents a simple index-guiding square photonic crystal fibers (SPCFs) that has a silica core surrounded by
air hole with two different diameters. It is demonstrated that the designed two-different-size hole-arrayed index-guiding
SPCFs has a ultra-flattened chromatic dispersion of 0 ± 0.9 ps/(nm·km) in a wavelength range of 1.34 to 1.61 μm and low confinement
loss of less than 10−7 dB/m in a wavelength range of 1.2 to 1.7 μm. It has also been shown that the proposed SPCFs show reasonable dispersion tolerance. 相似文献
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We numerically demonstrate ultraflattened chromatic dispersion with low losses in microstructured optical fibers (MOFs). We propose using two different MOF structures to get this result. Both structures are based on a subset of a triangular array of cylindrical air holes; the cross sections of these inclusions are circular, and a missing hole in the fiber's middle forms the core. In this MOF structure the diameters of the inclusions increase with distance from the fiber axis until the diameters reach a maximum. With this new design and with three different hole diameters, it requires only seven rings to reach the 0.2-dB/km level at lambda = 1.55 microm with a variation amplitude of dispersion below 3.0 x 10(-2) ps nm(-1) km(-1) of lambda = 1.5-1.6 microm. With the usual MOF (made from holes of identical diameter), we show that at least 18 hole rings are required for losses to decrease to < 1 dB/km at lambda = 1.55 microm. 相似文献
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LIU Tiegen ZHANG Fenglin R. A. Lessard 《Chinese Journal of Lasers》1998,7(6):491-494
1IntroductionAutomaticfocusingoftheopticalsystemplaysanimportantroleinautomation.Hereanewtechniqueofautomaticfocusingusinglas... 相似文献
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A novel photonic crystal fibre (PCF) with a low confinement loss and nearly zero ultra-flatted chromatic dispersion and negative chromatic dispersion at a wide telecommunication window is presented. Important PCF design parameters, such as the effects of air holes and geometrical parameters on the effective index, confinement losses, chromatic dispersion and effective mode area, have been thoroughly investigated by employing the full vectorial finite element method. Significant reduction of the confinement loss and low chromatic dispersion of the PCF, with three rings of air holes, has been obtained by carefully incorporating additional air holes. 相似文献
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Geometric Phase Observation with Dispersed Fringes 总被引:1,自引:0,他引:1
Geometric and dynamic phases are separately observed using dispersed fringes, and the difference between them is clearly demonstrated. Independence of geometric phase of wavelength is straightforwardly shown in the dispersed fringe. 相似文献
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在今年的高考复习资料中有这样一道题目:
如图1是观察薄膜干涉现象的示意图,酒精灯放在金属丝圈上的肥皂液薄膜前,在酒精灯火焰上洒一些氯化钠,使火焰发出黄光,则以下说法正确的是 相似文献
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以傅里叶变换为基础,提出了低倍率放大重构像全息干涉条纹的具体方法,它不仅光路简单,放大倍率可以人为选择,而且由此得到的全息干涉条纹效果很好. 相似文献
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We applied the classification image (CI) method to examine the effects of heterochromatic noise on color perception. Moreover, rather than the typical CI analysis procedure, we analyzed the CI data based on chromatic mechanism models. The stimulus was a superposition image of two uniformly colored squares (signal images) and a multicolored texture (a noise image), whose colors were chosen from an isoluminant plane of the Derrington-Krauskopf-Lennie color space. The observers judged the relative chromatic contrasts of the two signal squares on the different noise textures. The CI showed strong color modulations, whose color directions differed from the signal. Additionally, the model analysis demonstrated that the model with four mechanisms and the cardinal mechanisms model were not inferior to the model with more mechanisms with regard to explaining our experiment data; the cardinal model’s fit with the observer’s behaviors was improved by simply adjusting the relative sensitivities of the four mechanisms. 相似文献
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针对三维形貌测量中结构光照明系统投影速度慢、结构复杂、在线集成困难的问题,提出了一种基于声光栅的变频条纹投射系统。该系统利用拍频信号驱动声光偏转器,在声光晶体中形成两个重叠的光栅,光源发出的激光以布拉格角入射,形成两束一级衍射光,经透镜聚焦形成光强按正弦规律分布的结构光条纹。建立了数学模型,同时提出了一种新的相位凝固技术,使条纹空间频率和相位的变化规律得到了很好的解释。该系统结构紧凑、体积小,全电控可调,无任何机械移动部件,具有条纹投影速度快、精度高、动态可编程的特点。应用该系统对石膏像形貌进行测量,获得了用于三维成像的相位图。该投射系统对于解决复杂几何形状物体的三维测量问题具有较高的工程应用价值。 相似文献
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This paper presents a phase recovery method, based on genetic algorithms, in time-average shearography. It is proved that a single Bessel fringe pattern obtained under a subtraction operation could be enough to calculate the phase. A merit function is solved iteratively using genetic operator like selection, reproduction and mutation. Experimental results are presented in this paper using a simple shearing system based on a Fresnel biprism. 相似文献
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一种新的Fabry-Perot干涉条纹处理方法 总被引:1,自引:0,他引:1
介绍了一种提取Fabry-Perot(法布里-帕罗)干涉条纹圆心点坐标和条纹半径的新方法。首先对干涉图像依次进行二值化处理,对所得到的条纹强度曲线进行均平滤波和自适应滤波,根据条纹灰度值强度余弦函数分布的特点,对条纹灰度值数据进行最小二乘法拟合,获得条纹强度峰值坐标,通过精确的迭代算法,进而获得Fabry-Perot干涉条纹圆心点的坐标;然后再对干涉条纹进行圆周积分,从而可以确定每级Fabry-Perot干涉条纹的半径长度。该方法可提高计算精度,减小计算误差。 相似文献
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为了准确地测量透射平行平板,提出了基于最小二乘迭代的多表面干涉条纹分析方法.依据波长调谐相移的原理,通过最小二乘迭代准确地求得每组双表面干涉条纹的实际相移值.从而准确地提取平板前后表面面形及厚度变化等信息.模拟计算结果表明.当相移值有微小偏差(小于0.2 rad)时,通过10次迭代后求得相位的峰值(PV)误差为0.005 rad,均方根(RMS)误差为0.002 rad,而相应Okada算法的PV误差为0.512 tad.RMS误差为0.103 rad.实验结果验证了该箅法的有效性. 相似文献
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Self Mixing Fringes of Vertical-Cavity Surface-Emitting Lasers under Dual Reflector Feedback 下载免费PDF全文
The self-mixing fringes which shift due to every one-twentieth wavelength displacement of the target are observed. Taking advantage of the dual reflectors in the external cavity of lasers, the resolution of the sensors has been improved by 10 times. The role of the each reflector has been discussed in detail. 相似文献