Optics and photonics — Lasers and laser-related equipment — Laser-induced molecular contamination testing

ISO/TR 20811:2017 describes the setup, test procedure and analysis of measured data for investigation of laser-induced molecular contamination (LIMC) for space and vacuum applications.

LIMC is the formation of depositions on optical surfaces due to interaction of intense light radiation with outgassing molecules especially from organic materials. It is a phenomenon of molecular contamination and it is distinguished from particle contamination, which can occur during manufacturing, assembly, integration or test of the optical components.

Formation of laser-induced depositions can lead to deterioration of the performance of an optical system. Phase distortion, scattering and absorption can be increased by LIMC. LIMC is of particular relevance, if a laser system is operated in vacuum at short wavelength and short pulse duration. In such a case, even small partial pressure of contamination material in the range of 10 5 hPa could have strong negative impact on optical performance. It was also shown that the laser-induced damage threshold could be reduced by a factor of 10 and more if laser-induced depositions are involved.

Laser-induced molecular contamination and laser-induced damag