SEDL / STP / STP1028-EB / STP18560S

Dependence of Damage Threshold of Anti-Reflection Coatings on Substrate Surface Roughness

Nose, Y
Institute of Laser Engineering, Osaka University Suita, Osaka,

Kato, Y
Institute of Laser Engineering, Osaka University Suita, Osaka,

Yoshida, K
Institute of Laser Engineering, Osaka University Suita, Osaka,

Yamanaka, C
Institute of Laser Engineering, Osaka University Suita, Osaka,

Pages: 11    Published: Jan 1988

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Abstract

Geometrical shapes of the damage sites in the 5-layer SiO²/ZrO² anti-reflection (AR) coatings generated by lμm laser irradiation have been accurately determined. The damages can be classified into two types; deep damage and shallow damage, the former having the lower threshold. Dependence of the damage threshold of the deep damages on substrate surface roughness is given. It is suggested that presence of absorption centers embedded in the substrate is responsible for determining the damage threshold. Possible approaches that will lead to stronger AR coatings are proposed.