WIDEBAND ANTIREFLECTION FILM FOR ACOUSTO-OPTICAL TUNABLE FILTER

摘要

PURPOSE: A wideband antireflection film for an AOTF(Acousto-Optical Tunable Filter) is provided to enable a laser incident surface and a light-emitting surface of a TeO2 crystal to have less than 1.0 percent of reflectivity over a wavelength range of 450-700nm while manufacturing the antireflection film, thereby preventing an acousto-optical conversion efficiency from deteriorating. CONSTITUTION: Wideband antireflection films(20) are accumulated on a light incident surface(13) and a light-emitting surface(14) of a TeO2 single crystal(10). On the antireflection films(20), an MgF2 layer having a 1.38 refractive index and a TiO2 layer having a 2.4 refractive index are alternatively accumulated. When a design center wavelength is 550nm, the antireflection films(20) have an optical thickness expressed as TeO2/0.51924L O. 18377H O. 01804L O. 28558H O. 25739L/air. "L" means the MgF2 layer, and "H" refers to the TiO2 layer.