A modified two-aperture speckle shear interferometer that eliminates the contribution of the in-plane component and its derivative to the phase change, and yields a fringe pattern corresponding to the first-order partial derivatives of the out-of-plane displacement component, is reported in this note. In this method, two laterally sheared object points are viewed axially. The wave fields from these points are independently combined at the image plane of the imaging system. © 1998 Elsevier Science Ltd. All rights reserved.

Rajpal Singh Sirohi

Nandigana Krishna Mohan

Angle measurement

HOLOGRAPHIC INTERFEROMETRY

Imaging systems

LIGHT INTERFERENCE

Speckle

FRINGE PATTERNS

MULTIAPERTURE SPECKLE SHEAR INTERFEROMETRY

SLOPE MEASUREMENT

SPECKLE METROLOGY

Interferometers

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

An in-plane insensitive multiaperture speckle shear interferometer for slope measurement

Optics and Laser Technology

Digital speckle pattern interferometry (DSPI) and digital shearography (DS) are two independent useful whole-field noncontacting optical methods for nondestructive flaw detection and precision measurements. We describe a (1, N) spatial phase-shifting technique in DSPI and DS for nondestructive evaluation (NDE) of quasidynamic behavior of objects subject to slowly varying loads. The technique employs a double-aperture arrangement in front of the imaging system to introduce spatial carrier fringes within the speckle. The prominent advantage of the proposed technique is it requires only a single frame prior to the object deformation and a number N of frames during the object deformation for NDE. Quantitative measurement of a defect and its behavior in loading conditions are studied by recording spatially phase shifted frames before and during thermal stressing of the object for continuous deformation variation with time. Experimental results on a polymethyl methacrylate (PMMA) panel using an error-compensating five-phase-step algorithm for quantitative NDE using both DSPI and DS are demonstrated. © 2007 Society of Photo-Optical Instrumentation Engineers.

Optical Engineering

(1,N) spatial phase-shifting technique in digital speckle pattern interferometry and digital shearography for nondestructive evaluation

Digital speckle pattern interferometry (DSPI) and digital shearography (DS) are well known optical tools for qualitative as well as quantitative measurements of displacement components and its derivatives of engineering structures subjected either static or dynamic load. Spatial phase shifting (SPS) technique is useful for extracting quantitative displacement data from the system with only two frames. Optical configurations for DSPI and DS with a double aperture mask in front of the imaging lens for spatial phase shifting are proposed in this paper for the measurement of out-of-plane displacement and its first order derivative (slope) respectively. An error compensating four-phase step algorithm is used for quantitative fringe analysis. © 2006 Optical Society of America.

Fulltext

Optics Express

Use of spatial phase shifting technique in digital speckle pattern interferometry (DSPI) and digital shearography (DS)

Multiaperture speckle shear interferometry exhibits sensitivity to in–plane displacement components. The response of the interferometer to in–plane displacement, however, depends on the location of the shear element on an aperture in front of the imaging lens. Two configurations with three apertures, with the shear element positioned at two different locations, are examined theoretically and experimentally. © 1996 Optical Society of America.

Applied Optics

Fringe formation in multiaperture speckle shear interferometry

Speckle and speckle-shearing interferometer geometries have been combined into a single setup by the use of a small ground glass reference diffuser on the lens pupil. Sheared fields are obtained with a split lens arrangement. Judicious aperturing results in separated diffraction halos at the FT plane. Fringe patterns corresponding to out-of-plane displacement and slope are obtained by filtering via the appropriate halos. A four-aperture arrangement coupled with shearing elements extends the method to obtain the moiré curva ture pattern. © 1985 Optical Society of America.

Speckle and speckle-shearing interferometers combined for the simultaneous determination of out-of-plane displacement and slope

Split-lens speckle shear interferometry has been used to obtain slope data from loaded members. The information is usually recorded in the form of double-exposure records on a photographic plate, and only one set of data is recorded on a plate. A number of methods for storing multiple data on a single photographic plate and later retrieving them are discussed, and experimental results are presented. © 1984 Optica Acta All right reserved.

Optica Acta

Multiplexing in speckle shear interferometry

Laser Interferometry: Quantitative Analysis of Interferograms: Third in a Series

Sandwich Shearography: A Technique For The Cancellation Of Unknown Rigid Body Displacements In Shearography

Influence of in-plane displacement in single-aperture and double-aperture speckle shearing interferometry

Journal	Data powered by TypesetOptics and Laser Technology
Publisher	Data powered by TypesetElsevier Ltd
ISSN	00303992
Open Access	No