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Optical Engineering

Measuring effective area of spots from pulsed laser beams
Author(s): Aurel Stratan; Alexandru Zorila; Laurentiu Rusen; George Nemes
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Paper Abstract

The effective area of a laser spot is an important quantity used to characterize the laser-induced damage threshold of optical materials according to ISO 21254-1:2011 standard. A method for measuring the effective area/diameter of spots from pulsed laser beams using charge-coupled device camera-based beam profilers is presented. Factors affecting the measurement’s accuracy, as the background noise and the size of the summation area, were evaluated using MATLAB®. To minimize the noise contribution, we use an iterative method similar to the one used to measure the second-moment-based spot sizes. We find that the two analyzed components of the background noise, its zero-mean noise and its offset, have an opposite effect on the measurements of the effective area/diameter as compared with the second-moment-based measurements. We prove that there is an upper limit of the relative error of such iterative measurements of effective area, the iteration limit parameter, and that it is a measurable quantity. We measure the effective area/diameter of laser spots with different sizes from a Nd:YAG laser at 1064 nm, 6 ns pulse duration, 10 Hz repetition frequency, and estimate the standard uncertainty of the measurements. Further, we generalize the effective area/diameter concept to include elongated (elliptical/rectangular) spots.

Paper Details

Date Published: 8 October 2014
PDF: 11 pages
Opt. Eng. 53(12) 122513 doi: 10.1117/1.OE.53.12.122513
Published in: Optical Engineering Volume 53, Issue 12
Show Author Affiliations
Aurel Stratan, National Institute for Laser, Plasma and Radiation Physics (Romania)
Alexandru Zorila, National Institute for Laser, Plasma and Radiation Physics (Romania)
Laurentiu Rusen, National Institute for Laser, Plasma and Radiation Physics (Romania)
George Nemes, ASTiGMAT (United States)

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