共查询到20条相似文献,搜索用时 18 毫秒
1.
Application of digital phase-shift shadow Moiré to micro deformation measurements of curved surfaces
The shortcomings of conventional shadow Moiré topography have in the past been improved by means of the phase-shift method which enhances the sensitivity and allows to process the fringe patterns automatically. This paper presents a digital implementation of the phase-shifting process, which requires only one image to be taken. The grating lines, projected onto the deformed object surface, are captured directly with a digital camera. Next the reference grating is superimposed numerically onto the projected grating lines. Then a number of phase-shifts are performed taking into account the non-linearities in the expression for the height-dependent intensity field. Experimental results prove that these non-linearities can considerably affect the micro deformation measurements of curved surfaces. The proposed method is very efficient and eliminates all causes of erroneous measurements due to the miscalibration of phase-stepping devices. 相似文献
2.
Goul'kov M Odoulov S Naumova I Agulló-López F Calvo G Podivilov E Sturman B Pruneri V 《Physical review letters》2001,86(18):4021-4024
The first observation of parametric light scattering patterns (rings, lines, and dots) in bulk periodically poled nonlinear media is reported. Development of the scattering patterns proves efficient photorefractive grating recording and considerable parametric gain for seed radiation in this new nonlinear material. Several novel phase-matched parametric processes, caused by the periodicity of the domain structure, are revealed. 相似文献
3.
Huimin Xie Biao Li Robert Geer Bai Xu James Castracane 《Optics and Lasers in Engineering》2003,40(3):163-177
A focused ion beam (FIB) Moiré method is proposed to measure the in-plane deformation of object in a micrometer scale. The FIB Moiré is generated by the interference between a prepared specimen grating and FIB raster scan lines. The principle of the FIB Moiré is described. The sensitivity and accuracy of deformation measurement are discussed in detail. Several specimen gratings with 0.14 and 0.20 μm spacing are used to generate FIB Moiré patterns. The FIB Moiré method is successfully used to measure the residual deformation in a micro-electro-mechanical system structure after removing the SiO2 sacrificial layer with a 5000 lines/mm grating. The results demonstrate the feasibility of this method. 相似文献
4.
提出一种连续振动悬臂梁瞬时三维形貌的测量方法。利用影栅云纹法在连续振动悬臂梁表面产生包含有三维形貌信息的云纹,采用准直双光源提高亮度,通过高速摄相机获取随时间变化的一系列变形条纹,利用傅里叶变换方法对序列图像进行处理,采用补零延拓法对数据进行处理,以减小频谱泄漏所引起的相位计算误差。将相位解包裹方法用于动态过程瞬时三维相位场的相位展开中,重建了悬臂梁的瞬时三维形貌,再现了悬臂梁的连续振动过程。 相似文献
5.
The resolution of the electron beam moiré method depends on the line frequency of the grating. Recently, more and more effort has been devoted to increase the frequency, and a novel method for producing high-resolution electron beam gratings is presented in this work. Cross-gratings with a frequency up to 14,832 lines/mm (67 nm pitch) were successfully fabricated using a common scanning electron microscope without a dedicated pattern generation system. The quality of the grating was high enough to produce high-quality moiré fringe patterns. In this method, the ultra-fine cross-grating can be fabricated only through one-directional scanning on the resist, which can improve the grating quality and significantly reduces the fabrication time. The number of control parameters for grating fabrication could be reduced to two compared to the six parameters required by conventional methods, which facilitates the use of the electron beam moiré method. The frequency of the fabricated grating is linearly proportional to the exposure magnification. Thus, the frequency of the grating can be accurately predetermined, and the null field can be easily obtained in the electron beam moiré method. The quality of the fabricated gratings was illustrated by the obtained micrographs and moiré fringe patterns. The full-field local strain near an induced crack was studied to verify the application potential of this method. 相似文献
6.
The reflection grating method is a special case of the well-known reflection moiré principle. Whereas this moiré effect is suitable for measurement of the slope and curvature of deformed object surfaces by superposition of at least two grating images, the same results can be determined using only one reflected grating image without moiré lines.Some fundamental relationships between grating lines, optical setup and the desired deformation are developed and compared with the simplifications that are known from the moiré principle. The theory is tested using a circular plate, uniformly loaded and clamped at the circumference. 相似文献
7.
刻线误差与面型误差对平面光栅光谱性能影响的二维快速傅里叶变换分析方法 总被引:1,自引:1,他引:0
光栅刻线误差与基底面型误差影响平面光栅衍射波前、分辨本领、鬼线、卫线及杂散光等光谱性能,研究光栅性能指标与光栅刻线误差及基底加工误差之间的因果关系,对提高光栅质量极为重要。根据光栅衍射中产生的源于刻线误差与面型误差的光程差,推导出了在光栅锥面衍射情况下的光栅刻线误差、基底面型误差、入射角θ、衍射级次m与衍射波前关系的数学表达式,得到构建非理想光栅衍射波前的理论模型。以理论模型为依据,采用干涉仪测量光栅对称级次衍射波前,实现在测量结果中对光栅刻线误差与基底面型误差的分离,并基于二维快速傅里叶变换分析光栅衍射波前,考察了刻线误差与面型误差对光栅性能指标的影响。借助此方法通过重构的光栅衍射波前,分析光栅分辨本领、鬼线等光谱性能,还可以反演光栅全表面刻线误差与面型误差的大小,为光栅基底加工、光栅制造和使用技术提供理论依据。 相似文献
8.
When a slightly divergent laser beam passes through a turbulent ground level atmosphere and strikes a linear grating, fluctuating self-images are formed at Talbot distances. By superimposing a similar grating on one of the self-images, even for the case of parallel gratings' lines, fluctuating moiré fringes are formed owing to the beam divergence. Recording the successive moiré patterns by a CCD camera and feeding them to a computer, after filtering the higher spatial frequencies, produces highly magnified fluctuations of the laser beam. Using moiré fringe fluctuations we have calculated the fluctuations of the angle of arrival and the atmospheric refractive index structure constant. The implementation of the technique is straightforward, a telescope is not required, fluctuations can be magnified more than ten times, and the precision of the technique is similar to that reported in our previous work. 相似文献
9.
Mirjana?Bo?i? Milena?Davidovi? Teodora?L.?Dimitrova Salvador?Miret-Artés ángel?S.?Sanz Antoine?Weis 《Journal of Russian Laser Research》2010,31(2):117-128
We study experimentally and theoretically the influence of light polarization on the interference patterns behind a diffracting
grating. Different states of polarization and configurations are considered. The experiments are analyzed in terms of electromagnetic
energy (EME) flow lines, which can be eventually identified with the paths followed by photons. This gives rise to a novel
trajectory interpretation of the Arago–Fresnel laws for polarized light, which we compare with interpretations based on the
concept of “which-way” (or “which-slit”) information. 相似文献
10.
M. Medhat 《Optics and Lasers in Engineering》1991,15(1)
A new kind of chromatic interference fringe is produced by crossing the dispersion of a plane diffraction grating by an auxiliary dispersion (a spectograph). These are called fringes of equal chromatic low orders, since they have orders of values 0, ±1, ±2,..., etc. The fringes are straight chromatic lines having a separation which is directly proportional to the wavelength. These fringes can be used to measure exactly the grating space, and they afford a continuous wavelength calibration of the auxiliary spectograph. The wavelength can be determined accurately to ±0.04% with a grating having 2000 lines of spacing 0.05 mm. 相似文献
11.
Recent experiments using a grating coupled low-index nanoporous silica supported monomode waveguide have demonstrated that
living cells can cause heavy distortion of the grating coupler resonance lines, in some cases even leading to a separation
into two resonance peaks. These findings stand in contrast to previously reported data, where simple peak broadening was observed
during cell attachment and spreading using less sensitive waveguide designs. In order to explain these observations, we apply
the local interference method to simulate the effects of inhomogeneity patterns on the surface of grating coupled planar optical
waveguides and obtain the resonant peaks for the modes. It is shown that analyte inhomogeneities affect both the position
and shape of the resonant peaks. Depending on the deposited cell or domain size, refractive index contrast and waveguide design,
peak shift, peak deformations or peak splitting can be observed. On the basis of simulation data, characteristic parameters
of the resonant peaks such as peak width at half maxima, overall width, central position and peak integral are connected for
the first time to quantitative parameters of the inhomogeneity patterns; like analyte covered sensor area, surface averaged
effective refractive index and domain size. Our results indicate that by careful investigations of the incoupling resonant
peaks, quantitative information about sample inhomogeneities at the micrometer scale can be obtained, thus allowing for a
new generation of simple, low cost, label free and imageless optical sensors, which are well suited for high throughput screening
applications.
PACS 42.82.Et 相似文献
12.
R.P. Shukla N.C. Das Murty V. Mantravadi D. Cook M.D. Aggarwal 《Optics & Laser Technology》2007,39(2):338-346
The design and fabrication of holographic gratings of frequency variable from 50 to 750 lines/mm over length of 75 mm have been described. An application of these variable frequency gratings as a lateral-shear interferometer has also been suggested. The variable shear interferometer is found to be useful for testing of lenses with a maximum sensitivity in the detection of wavefront aberrations. Comparison of single-frequency grating having uniform pitch of 100 lines/mm with a grating of frequency variable from 59 to 220 lines/mm using an average pitch of 100 lines/mm over a small area as a lateral-shear interferometer have been made. Our experimental observations show that a small area of average pitch of 100 lines/mm on the grating having a variable frequency of 59–220 lines/mm over a distance of 75 mm behaves as a lateral-shear interferometer in the same way as any area of pitch of 100 lines/mm on the grating of uniform pitch of 100 lines/mm. 相似文献
13.
将激光扫描共聚焦显微镜与实验力学中的云纹法相结合,提出了激光扫描共聚焦显微镜云纹法并对其进行了实验研究.实验中以激光扫描共聚焦显微镜的扫描线作为虚拟参考栅,以1 200 lines/mm的全息光栅作为试件栅,这两组栅线相干涉形成云纹条纹.对激光扫描共聚焦显微镜中云纹的形成原理和出现条件进行了讨论,对实验结果与理论分析进行了比较.结果表明,激光扫描共聚焦显微镜云纹法是真实可行的.由于该方法无需干涉系统且对测量环境无特殊要求,因此有望在待测物体表面微米量级变形观察和测量上得到应用. 相似文献
14.
液体表面波光栅的研究 总被引:7,自引:0,他引:7
在液体表面形成的一维正弦形表面波,作为一种理想的反射式光栅,称之液体表面波光栅.本文通过它对激光束的衍射,研究液体表面与界面的物理特性. 相似文献
15.
This paper proposed new ways for producing multi-layer model grids for electron beam moiré method. An electron beam lithography system was set up under scanning electron microscope which was equipped with a beam blanking device and a pattern generator. The two-deposited-metal layers method was used to manufacture electron beam grating for high-temperature use. The results verify that the Zr–Pt-type grating possesses heat resistance up to 1100°C in vacuum. A new type of composite grating with frequencies 100 lines/mm and 1000 lines/mm using three deposited layers was produced. A 10 000 lines/mm two-deposited-metal layers grating was successfully fabricated using electron beam lithography. 相似文献
16.
从实验和机理上研究了四棱镜扩束染料激光器产生的多线振荡,结果表明:其振荡线间隔、单线线宽、多线带宽是与多界面反射器-光栅复合腔对光束的频率和空间调制特性相符合的. 相似文献
17.
The diffraction of thermal neutrons by a plane Ni covered ruled grating was investigated at various angles of incidence. A 54 lines per mm grating was used in the reflection case. The diffraction pattern was observed on both sides of the beam reflected in zero order (total reflection). Measured and calculated intensities are compared. 相似文献
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20.
设计了一种用于裸眼3D显示屏的低串扰新型双面柱透镜光栅板,光栅板的入射面为等间距排列的与显示器子像素数量相同的凹形自由曲面光栅结构,出射面为斜置的凸形自由曲面光栅结构.根据裸眼3D显示原理和几何光学原理推导了双面光栅板的光栅单元自由曲面设计公式和光栅参数计算公式.通过MATLAB编程计算和SolidWorks软件建模得到光栅板模型.用TracePro软件对所设计的光栅板模型进行光线追迹仿真,结果表明:参数优化后的6视点斜置柱透镜双面光栅3D显示在最佳视角的图像串扰度为0.068%,与传统6视点斜置柱透镜光栅的最佳视角图像串扰度相比降低了2个数量级,并且在观看距离2 000mm~3 000mm范围内图像串扰度基本不变. 相似文献