HfO2/SiO2 enhanced diamond turned aluminum mirrors for IR laser optics

HfO 2 /SiO 2 multilayers were deposited on single point diamond turned aluminum substrates via modified reactive plasma ion assisted deposition to form a laser durable and environmentally stable dielectric enhanced IR mirror at a wavelength of 1064nm. The effect of the surface quality of the diamond turned aluminum on the optical performance of the dielectric enhanced mirror was assessed. A laser-induced damage threshold up to 11 J/cm 2 was obtained from the enhanced aluminum mirror tested in pulse mode at 1064nm with a pulse length of 20ns and a repetition rate of 20Hz. Laser damage morphology was revealed by a scanning electron microscopy. The damage mechanism was attributed to nodule defects generated by particle embedded on the aluminum substrate surface.