Composite organic-inorganic coatings are realized by ion beam sputtering (IBS) from a zone target consisting of PTFE and Al2O3. The composition of the sputtered coatings is measured by Energy-Dispersive X-ray spectroscopy and the molecular structure is analyzed by Fourier Transform Infrared spectroscopy. The variation of the refractive index and the optical quality in dependence of the carbon-fluorine content for different material compositions is investigated. Furthermore, the intrinsic stress of the coatings is analyzed and a change from compressive to tensile stress in dependence of the composition is observed. The production of ion beam sputtered composite coatings with low refractive index and tensile stress is demonstrated.
Contamination plays a major role in lifetime of vacuum optics. Several efforts have been made to derive suitable models
for lifetime prediction in laser-induced contamination related optical breakdown. But the broad spectrum of potential
contaminants present in the various applications with their very specific contamination mechanisms complicates the
derivation of universal optics degradation models.
As one possible contamination initiation process, the impact of optical absorption on the laser-induced contamination
and resulting optical breakdown is studied in this work. A set of specifically prepared samples using nanometer sized
gold particles embedded in dense IBS anti-reflecting coatings is exposed to radiation of 355nm in low pressure
naphthalene atmosphere. Even though the artificial defects are not in direct contact with the contaminant, their influence
on the long-term optics performance in dependence on the particle concentration in the coating is evident. In the
presence of naphthalene, the artificial nano-defects cause a significantly accelerated degradation compared to reference
samples without those defects or in absence of the contaminant. For this specific type of contaminant, a correlation of the
optical absorption and long-term durability is derived.