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Optical Engineering

Step height determination by a focused Gaussian beam
Author(s): Danny Levy; Liviu Singher; Joseph Shamir; Yehuda Leviatan
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Paper Abstract

The interaction of a focused laser beam with a step on a conducting surface is investigated by a vector method. The 2-D problem is solved by using a model of fictitious current filaments, while 3-D problems are treated by using a model of fictitious dipoles as the sources of the scattered field. Computer simulations indicate a difference between the two polarization components (TE and TM), but with the samples investigated in this work, these differences are too small for practical measurements. The scattered field distribution is found to be strongly dependent on the step height relative to the observation plane and on its position relative to the beam waist. Thus, measurements of the intensity distribution in the observation plane can provide information about these parameters with high sensitivity. Experimental investigation confirms that the height of a step in the range λ/10 to λ/4 can be measured with an accuracy of 5%, including its sign (up or down). The position of the step with respect to the beam can be estimated with an accuracy of about 1/100 of spot size.

Paper Details

Date Published: 1 November 1995
PDF: 11 pages
Opt. Eng. 34(11) doi: 10.1117/12.212912
Published in: Optical Engineering Volume 34, Issue 11
Show Author Affiliations
Danny Levy, Technion--Israel Institute of Technology (Israel)
Liviu Singher, Technion-Israel Institute of Technology (Israel)
Joseph Shamir, Technion-Israel Institute of Technology (Israel)
Yehuda Leviatan, Technion--Israel Institute of Technology (Israel)

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