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Proceedings Paper

Throughput vs. the M2 quality factor
Author(s): Javier Alda; Jose Alonso; Eusebio Bernabeu
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Paper Abstract

The quality parameter M2 has been accepted as an useful averaged magnitude for comparing and classify laser beams with respect to their behavior in their propagation. Its definition is based on the product of two magnitudes: (the spatial size of the laser beam) X (the angular size of the laser beam). This product resembles very much a characteristic magnitude used in radiometry: the throughput, or etendue. In this work we will relate both concepts in order to identify one to the other. From a radiometry point of view the laser beam propagation can be seen as the transportation of light flux from a given source plane to a receiving plane. In most of the cases the practical situation involving laser beam propagation requires this kind of radiometric calculation for safety and energy delivery purposes. On the other hand the radiance of a laser source has been formally related with the Wigner distribution what show up some close relations between moment parametrization of laser beams and radiometric magnitudes. The description of the laser beam in terms of the moments of its amplitude distribution works very well in the formalism but it finds some difficulties to be reached in an experimental setup. Otherwise, the measurement of the energy of the beam can be easily obtained by several methods, such as the knife edge technique and some other related procedures. Our goal is find out the intrinsic relations between the easy to measure radiometric quantities and the easy to calculate generalized parameters. We will focus our attention in the relation between quality factor and throughput.

Paper Details

Date Published: 9 October 1998
PDF: 12 pages
Proc. SPIE 3418, Advances in Optical Beam Characterization and Measurements, (9 October 1998); doi: 10.1117/12.326650
Show Author Affiliations
Javier Alda, Univ. Complutense de Madrid (Spain)
Jose Alonso, Univ. Complutense de Madrid (Spain)
Eusebio Bernabeu, Univ. Complutense de Madrid (Spain)

Published in SPIE Proceedings Vol. 3418:
Advances in Optical Beam Characterization and Measurements
Michel Piche, Editor(s)

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