Laser damage testing of silica windows with hydrophobic antireflective surfaces (Conference Presentation)

Antireflective surface structures (ARSS) are nano-patterned structures etched into the optical surface that simulate behavior like that of a moth’s eye, which has cone-like structures that reduce reflections in the visible. We have previously reported record high laser induced damage thresholds (LIDT) up to 100 J/cm2 at 1 µm (10 nsec pulsewidth) for silica glass windows with random ARSS. However, these windows with ARSS are hydrophilic, leading to practical problems for their use in fielded laser systems. Recently, we developed and reported a new process for treating the surface of silica windows with ARSS such that it becomes hydrophobic. In this paper we will report results for the LIDT for samples with these antireflective, hydrophobic surfaces, and compare to results for samples that are untreated but have ARSS, samples with hydrophobic treatment but no ARSS, and finally those having neither ARSS or hydrophobic treatment. The morphology of the laser damage observed and potential mechanisms will be discussed.