Patent ID: 9470872
Filing Date: 2016-10-18
CPC Classification: G01N,G02B,G03F,G21K

Claim Text:
1. Reflective optical element having an optically effective surface and comprising: an element substrate; a reflection layer system; at least one deformation reduction layer which, upon the optically effective surface being irradiated with electromagnetic radiation, reduces a maximum deformation level of the reflection layer system in comparison with an analogous construction of a reflective optical element without the deformation reduction layer; and an intermediate layer arranged between the reflection layer system and the deformation reduction layer and configured to block transfer of surface roughnesses to the reflection layer system, wherein the reflection layer system comprises at least one layer composed of a first material having a first coefficient of thermal expansion, and the at least one deformation reduction layer comprises a second material having a second coefficient of thermal expansion, and wherein the first and the second coefficients of thermal expansions have mutually opposite signs.