Two methods of sharpening the interference fringes in lateral shear interferometry are described. One method exploits the non-linearity of the recording process, while the other is based on the characteristics of the multiply-recorded diffractive element. Both methods can be combined to obtain further fringe sharpening in the higher orders. © 1985.

R. K. Mohanty

Rajpal Singh Sirohi

Interferometry

optics

FRINGE SHARPENING

LATERAL SHEAR INTERFEROMETRY

MULTIPLE SHEAR LENS

Interferometers

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IIT Madras

Fringe sharpening in lateral shear interferometry

Optics and Laser Technology

Lateral shear interferometry is used to obtain the lateral aberrations of a lens. The zeroth-order fringe in an interferogram obtained from a wedge-plate lateral shear interferometer, however, directly displays the lateral aberration curve of a test lens. Nevertheless, the intensity distribution, is cosinusoidal. Multiple-beam interferometry results in sharpened fringes; hence the multiple-beam wedge-plate shear interferometer displays the lateral aberration curve of a lens sharply, provided the shear is small. For large shear, some new artifacts appear in the interferogram, which are also explained. © 1995 Optical Society of America.

Applied Optics

Multiple-beam lateral shear interferometry for optical testing

The advances in electronic speckle pattern interferometry (ESPI) have been rapid and are well documented. 1-3 The recent trend is to digitally store the speckle patterns in a host computer and process them.4-5 This technique is called digital speckle pattern interferometry (DSPI). As the data are available in digital form, there is more flexibility in handling the data. To automatically process the data available in the form of fringe patterns, the fringe centers have to be located. It has been pointed out that the process of fringe center determination is tedious and quite difficult in speckle interferometry. © 1988, Optical Society of America.

Sharpening of fringes in digital speckle pattern interferometry

A simple method for obtaining lateral shear using holo shear lenses (HSL) has been discussed. This simple device which produces lateral shears in the orthogonal directions has been used for lens testing. The holo shear lens is placed at or near the focus of the lens to be tested. It has also been shown that HSL can be used in speckle shear interferometry as it performs both the functions of shearing and imaging. © 1984.

Optics Communications

Lateral shear interferometry with holo shear lens

Fringe sharpening is required to obtain a higher accuracy of measurement. Nonlinear recording and consequently filtering at the higher-order halos for image formation give sharpened fringes in the image. Furthermore, if the apertures during recording are properly arranged, cross-frequency orders appear, which when used for filtering provide moiré fringes of higher contrast due to intercoupling. © 1984 Optical Society of America.

Journal	Optics and Laser Technology
ISSN	00303992
Open Access	No