Open AccessDetermining and scaling continuous-wave, laser-induced damage thresholds of thin reflectors
Author(s) -
Keith Slinker,
Jeremey Pitz,
Sangwook Sihn,
Jonathan P. Ver
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.004748
Subject(s) - optics , irradiance , materials science , laser , continuous wave , beam (structure) , optical coating , scaling , thin film , coating , optoelectronics , physics , composite material , geometry , mathematics , nanotechnology
Scalable and repeatable determinations of continuous wave (CW) laser-induced damage thresholds are required to develop materials for applications ranging from deformable mirrors to momentum transfer. Current standards assume sample geometries and beam conditions where CW damage thresholds are constant in linear power density, depend strongly on substrate thermal conductivity, and are insensitive to environmental conditions. In this work, the CW laser response of thin PET films with a reflective Al/MgF 2 coating are experimentally assessed over a range of beam diameters and irradiances. The laser-induced damage threshold decreases with increased exposure time down to a temporally-independent irradiance, decreases with increased beam diameter to an irradiance that is independent of spot size, and depends on radiative and convective cooling. Models are used to define the minimum spot size and exposure time required to achieve such constant damage threshold irradiances for thin reflectors.