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Shearing Interferometer

IP.com Disclosure Number: IPCOM000092752D
Original Publication Date: 1967-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Lohmann, AW: AUTHOR

Abstract

The shearing interferometer allows a variable shift between two images and provides for interference between these images of equal amplitudes. The radiation from source S is collimated by lens L1. Lens L2 performs a Fourier trasformation on the light diffracted by object 0. Grating G1, rotated by an angle +phi in the Fraunhofer diffraction plane, provides the usual diffraction orders which are imaged by lens L3 at mask M.

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Shearing Interferometer

The shearing interferometer allows a variable shift between two images and provides for interference between these images of equal amplitudes. The radiation from source S is collimated by lens L1. Lens L2 performs a Fourier trasformation on the light diffracted by object 0. Grating G1, rotated by an angle +phi in the Fraunhofer diffraction plane, provides the usual diffraction orders which are imaged by lens L3 at mask M.

The windows in mask M permit passage of the +1st and -1st order images. L4 performs a Fourier transformation of the +1st and -1st order images. A second grating G2, oriented at -phi, provides the diffraction orders shown which are imaged in the image plane 1 by lens L5. As shown, the -1st order of the +1st order image at M, interferes with the +1st order of the -1st order image at M.

The shift delta x is lateral and is determined by the angle between gratings G1 and G2. Any desired shift can be obtained according to delta x = 2 lambda fsin theta/d, where theta=wavelength, f = focal length, and d = grating constant.

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