混合膜法による高出力レーザー用蒸着膜
1990 年 59 巻 7 号 p. 953-958
詳細
1990 年 59 巻 7 号 p. 953-958
Mixed films were produced by means of composite-multilayer method and co-evaporation method to obtain any specified refractive-index or stress of thin films. The refractive-index of mixed film with SiO2-ZrO2 was almost the same as the calculated value from Lorentz-Lorenz formula. Two-wavelength antireflection (AR) coatings with composite-multilayer method were produced for the first time by combining the mixed films with SiO2-ZrO2 and MgF2 on fused-silica and BK-7 glass substrates. The laser damage threshold of this AR coating was measured to be 10_??_12 J/cm2 at 1.064 μm (pulse-width τp=1 ns) and 10_??_11 J/cm2 at 0.532 μm (τp=1 ns), respectively. Also, the relation between laser damage threshold and stress of thin films were examined by using the SiO2-MgF2 mixed film and high reflectance mirror produced by mixed film with SiO2-MgF2 and ZrO2. As a result, it has become clear that the laser damage threshold with τp of less than 1 ns is not affected from stress of less than 3000 kgf/cm2 on thin films.
