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Two-Dimensional Interferometric Phase Contrast Analysis

IP.com Disclosure Number: IPCOM000116662D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Wagner, D: AUTHOR

Abstract

Disclosed is a two-dimensional phase contrast analysis method measuring phase shifts in direct illumination and in transillumination with TV cameras with an accuracy of 5 A. This phase contrast analysis offers a broad variety of different applications for wafers, masks, specular surfaces and in biology to represent numerous very small and different phase shifts of high contrast.

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Two-Dimensional Interferometric Phase Contrast Analysis

      Disclosed is a two-dimensional phase contrast analysis method
measuring phase shifts in direct illumination and in
transillumination
with TV cameras with an accuracy of 5 A.  This phase contrast
analysis
offers a broad variety of different applications for wafers, masks,
specular surfaces and in biology to represent numerous very small
and different phase shifts of high contrast.

      In the arrangement for the phase contrast analysis a Nomarski
interferometer is used.  In this kind of interferometer measuring
beam and reference beam are closely spaced and it may easily be
integrated into each kind of microscope.  The monochromatic light
beam
from a lamp becomes linearly polarized with 45 degrees to the main
axis of the Wollaston prism by a polarizer.  In the Wollaston prism
the beam is split into two coherent partial beams being orthogonally
polarized with respect to each other.  Passing a condenser the
partial beams strike onto the object at different places and are
phase shifted.  The objective forms the image of both the partial
beams on the TV camera.  In the second Wollaston prism the two
partial beams are superposed and the quarter wave plate changes the
linearly polarized beams into a right side circularly polarized wave
and a left side circularly polarized wave.  The right side and left
side circularly polarized waves are superposed to a linearly
polarized oscillation which contains the information on the phase
shift of the object in the direction of the linearly polarized
oscillation.  The polarizer allows to pass only components of a
well-defined direction of oscillation.  Those components may
interfere.  With the ro...