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Laser conditioning of LaF3/MgF2 dielectric coatings at 248 nm



Applied optics 35 (1996), pp.5613-5619
ISSN: 0003-6935
ISSN: 1539-4522
ISSN: 1559-128X
Journal Article
Fraunhofer IOF ()
Dünne optische Schicht; excimer laser optics; fluoride thin films; Fluoridschicht; laser induced damage threshold; Laserzerstörschwelle; optical coating; optical thin films; oxide thin films; Oxidschicht; ultraviolet spectral region; ultravioletter Spektralbereich; UV

Highly reflective LaF3/MgF2 systems for a wavelength of 248 nm on MgF2 and crystalline quartz substrates were investigated. The influence of laser conditioning on damage threshold and absorptance was remarkable in those coatings that had a high initial absorptance. Monitoring with a laser calorimeter revealed the conditioning effect to be a function of the irradiation dose rather than of energy density or pulse rate. Furthermore, x-ray photoelectron spectroscopy and transmission electron microscopy investigations showed that conditioning induces stoichiometric and structural changes in the multilayers, especially in near-surface sublayers, whereas scanning electron microscopy and atomic force microscopy investigated that the surface remains unchanged.