The Laser MégaJoule (LMJ) is a French high power laser that requires thousands of large optical components. For all those optics, scratches, digs and other defects are severely specified. Indeed, diffraction of the laser beam by such defects can lead to dangerous “hot spots” on downstream optics. With the help of a near-field measurement setup, we make quantitative comparison between simulated and measured near-fields of reference objects (such as circular phase steps). This leads to a better understanding which parameters impact the diffracted field. In this paper, we proposed to study two types of reference objects: phase disks and phase rings. We actually made these objects by CO2 laser ablation. The experimental setup to observe the diffracted intensity by these objects will be described and calibrated. Comparisons between simulations and measurements of the light propagation through these objects show that we are able to predict the light behavior based on complete phase measurement of these objects.

Date Published: 11 December 2017
PDF: 10 pages
Proc. SPIE 10447, Laser-Induced Damage in Optical Materials 2017, 104471Y (11 December 2017); doi: 10.1117/12.2287431

Published in SPIE Proceedings Vol. 10447:
Laser-Induced Damage in Optical Materials 2017
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; MJ Soileau, Editor(s)