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Proceedings Paper

Partially coherent imaging of semi-transparent edges: the effect of the phase part
Author(s): Andreas Glindemann
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Paper Abstract

Applying the extended linear approximation'' to defocused imaging of semitransparent edges with weak phase part allows to study the influence of modulus and phase on the ima ge characteristics. It is shown that the influence of the phase part on the defocused image depends on the sign of defocusing and is a purely linear effect of the imaging pro cess. Defocusing is one of the oldest methods to detect weak phase objects. In the image of semitransparent edges a weak phase part is visible only in the defocused image too. In microlithography one might be interested in the focused image of the waver structure only but in searching for the exact focus position the remaining phase part in the object may have some influence on the intensity distribution2. Imaging surface steps on a waver the exact focus position is furthermore difficult to defines. The change of spatial symmetry from the object into the image for both the amplitude and the intensity is caused by the nonlinear transfer of both quantities in partially coherent imaging. Therefore two transfer functions (one symmetrical and one nonsymmetri cal) are used within the extended linear approximation to describe this effect. Recently *e have given the formulae for the image intensity distribution of semitransparent edges +. If these are applied to defocused imaging of semitransparent edges with a weak phase part it turns out that the difference

Paper Details

Date Published: 1 July 1990
PDF: 1 pages
Proc. SPIE 1319, Optics in Complex Systems, (1 July 1990); doi: 10.1117/12.34751
Show Author Affiliations
Andreas Glindemann, Optisches Institute (Germany)

Published in SPIE Proceedings Vol. 1319:
Optics in Complex Systems
F. Lanzl; H.-J. Preuss; G. Weigelt, Editor(s)

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