1 December 2004 Simultaneous and real-time measurement of slope and curvature fringes in thin structures using shearing interferometery
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Optical Engineering, 43(12), (2004). doi:10.1117/1.1809611
Abstract
A real-time lateral shearing interferometry that uses a pair of Ronchi gratings to perform wavefront shearing operations is described for measuring slope and curvature fringes simultaneously in thin structures. It involves simultaneous imaging of diffracted wavefronts using Fourier filtering. Two sets of fringe patterns, one representing slopes and the other curvatures, occur simultaneously at spatially distinct locations on the image plane, thereby eliminating the need for additional postprocessing of the recordings. In this work, the principles involved in the measurement of slopes and curvatures using this technique are explained. The method is then demonstrated on thin structures subjected to well-defined loading conditions, such as a clamped circular silicon wafer subjected to central displacement. Measurements have been successfully compared with analytical solutions.
Hareesh V. Tippur, "Simultaneous and real-time measurement of slope and curvature fringes in thin structures using shearing interferometery," Optical Engineering 43(12), (1 December 2004). http://dx.doi.org/10.1117/1.1809611
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KEYWORDS
Diffraction

Diffraction gratings

Wavefronts

Semiconducting wafers

Ronchi rulings

Silicon

Shearing interferometers

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