Simultaneous and real-time measurement of slope and curvature fringes in thin structures using shearing interferometery

Hareesh V. Tippur

doi:10.1117/1.1809611

1 December 2004 Simultaneous and real-time measurement of slope and curvature fringes in thin structures using shearing interferometery

Hareesh V. Tippur

Author Affiliations +

Optical Engineering, Vol. 43, Issue 12, (December 2004). https://doi.org/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.

©(2004) Society of Photo-Optical Instrumentation Engineers (SPIE)

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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). https://doi.org/10.1117/1.1809611

Published: 1 December 2004

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