Application of Speckling for In-plane Vibration Analysis

Tiziani, Hans J.

doi:10.1080/713818406

Cited by 101 publications

(23 citation statements)

References 9 publications

(12 reference statements)

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“…This scheme is close, in principle, to schemes used for the analysis of deformations of transparent objects, where the initial and inclined (with respect to the axis lying in the plane of an object) states of an object are recorded [13,14]. The spectrum of spatial frequencies is formed by optical system OS1.…”

Section: Aoz~k = Al Dnk(~k) D~kmentioning

confidence: 99%

Application of speckle interferometry to the analysis of refractive-index gradients in flows

et al. 1999

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A version of a scheme of speckle intefferometry is considered, which is intended for the analysis of the distribution of refractive-index gradients in optically transparent media. The application of this approach to problems of hydrodynamics and gas dynamics makes it possible to determine the structure of the distribution of optical inhomogeneities in liquid and gaseous flows. The method is based on the recording of patterns of two speckle structures obtained in the plane of spatial frequencies by using illumination with an auxiliary speckle structure. One speckle structure is formed in the absence of an object, and the other one is formed by transilluminating an object. In comparison with other known phase methods, the speckle-interferometry methods make it possible to change the measurement sensitivity in a wide range and substantially simplify the interpretation of the results obtained.

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Section: Aoz~k = Al Dnk(~k) D~kmentioning

confidence: 99%

Application of speckle interferometry to the analysis of refractive-index gradients in flows

et al. 1999

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“…The speckle pattern technique seems to be well suited for problems involving surface phenomena, fragile specimens and others [1][2][3]. A speckle pattern formed by partially spatially coherent light has been studied theoretically by many authors [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Partially Coherent Light on the Contrast of Speckle Patterns Obtained Using Digital Image Processing of Speckle Photography

Moustafa¹,

El‐Nicklawy²,

Hassan³

et al. 2013

OPJ

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The paper is devoted to study theoretically, the effects of some parameters on the visibility of the speckle patterns. For this propose, a theoretical model for a periodic rough surface was considered. Using this theoretical model, the effects of grain height, its density, the band width and spectral distribution of the line profile (Gaussian and Lorentzian) illuminating a rough surface on the visibility of speckle pattern are investigated. An experimental setup was constructed to study the effect of surface roughness and coherence of the illuminating light beam on the contrast of speckle pattern. The general behavior of the experimental results, which agree with published data, is compatible with the new theoretical model.

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“…(10) An interesting observation can be made when the timeaverage speckle pattern is first recorded and then superimposed on the speckle pattern of the stationary object.…”

Section: I1 Study Of Diffraction Of Speckle Patterns Recorded In Foumentioning

confidence: 99%

Analysis of Mechanical Oscillations by Speckling

Tiziani¹

1972

Appl. Opt.

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The application of the speckle phenomenon to the analysis of in-plane translations and oscillations is first reviewed briefly. Then a practical method of investigating out-of-plane rotations (tilts) even in the presence of in-plane movements is studied. This goal can be achieved by recording the speckle patterns in the Fourier transform plane before and after the tilt or as a time-average exposure for an oscillating object. Young's fringes related to the tilts are observed in the Fraunhofer diffraction pattern when the developed photographic plate is illuminated with coherent light. This leads to a very simple engineering tool for the analysis of movements. Theoretical and experimental results will be shown. I. Review of Previous WorkAn optically rough surface illuminated with highly coherent light, such as from a laser, leads to a speckled appearance everywhere in space. The main features of the speckle patterns in the Fourier transform plane as well as in the image were investigated recently by a number of authors. [1][2][3][4] The application of the speckle phenomenon for the measurement of in-plane translations and rotations was investigated lately.'-2 In addition, this technique was found convenient for the investigation of in-plane oscillations. 1 0-1 2 Vibratory movements perpendicular to the object surface were studied by the observation of the contrast reduction in the speckle patterns."3-" An object surface with a given roughness leads to a particular speckle pattern in the Fourier transform plane as well as in the image plane. The smallest dimensions of the individual speckle in the image and in the Fourier transform plane are inversely proportional to the lateral dimensions of the lens aperture and the illuminated object field, respectively.1-4 Let us consider the surface itself to be characterized by the coherent speckle pattern generated by illuminating it with laser light. To simplify the argument this speckle pattern may be considered to be attached to the optically rough object. Photographing the speckle patterns before and after the movement of the surface has taken place will lead to two practically identical, but shifted speckle patterns from which the in-plane translation or rotation can be derived by analyzing its optical diffraction effect.It was shown 6 -" that by recording two identical, but where f, is the focal length of the lens or the distance between the developed photographic plate and the focal

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Application of Speckling for In-plane Vibration Analysis

Cited by 101 publications

References 9 publications

Application of speckle interferometry to the analysis of refractive-index gradients in flows

Application of speckle interferometry to the analysis of refractive-index gradients in flows

Effect of Partially Coherent Light on the Contrast of Speckle Patterns Obtained Using Digital Image Processing of Speckle Photography

Analysis of Mechanical Oscillations by Speckling

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