Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1664546 | Thin Solid Films | 2015 | 5 Pages |
Abstract
Laser durable multiband high reflective optics can be attained by depositing HfO2/SiO2 stacks on diamond-turned and optically polished aluminum alloy substrates. HfO2 and SiO2 single layers were prepared using modified plasma-ion assisted deposition. Ellipsometric measurements were performed using two types of variable angle spectroscopic ellipsometry with a combined spectral range of 150 nm to 14 μm. Optical constants were generated in the entire spectral range. Scatter loss as a function of surface roughness was calculated at 1064 nm, 1572 nm, and 4.1 μm, representing a primary wavelength, a secondary wavelength, and a middle wave infrared band selected for a dual-wavelength laser beam expander, respectively. The surface requirement of the aluminum alloy substrates was determined. Calculated and measured spectral reflectances were compared. Laser-induced damage threshold tests were performed at 1064 nm, 20 ns, and 20 Hz. A laser-induced damage threshold of 47 J/cm2 was determined. Post-damage analysis suggests that nodule defects are the limiting factor for the laser-induced damage threshold. Surface modification of the aluminum alloy was identified as a potential technical solution that may further increase the laser damage resistance of the dielectric enhanced dual-wavelength reflective optics.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Nanotechnology
Authors
Angela Q. Wang, Jue Wang, Michael J. D'lallo, Jim E. Platten, Joseph C. Crifasi, Brian P. Roy,