Characterization

Test Method	Wavelength and Operation Parameters
ISO 11254 Laser-induced Damage Threshold	157 nm, 193 nm (13ns), 780 nm (150fs), 1064 nm (10ps-50ns, cw), 10.6 µm 355nm, 532nm, 1064nm, 10.6µm
ISO 11551 Absorptance	157 nm, 193 nm, 355nm, 532nm, 780 nm (150fs), 1064nm, 10.6µm
Laser-induced Fluorescence	157nm od. 193nm (excitation), 200 – 850nm (fluorescence measurement)
ISO 13696 Total Scattering	157nm, 193nm, 633nm, 1064nm
ASTM E1392 Angle-resolved Scattering	115 – 300 nm (vacuum, purging), 350 – 850nm, 1064nm
ISO/FDIS 13697 High-precise R/T-Measurement	532nm, 633nm, 1064nm, 10.6µm
ISO 15368 Spectrophotometry	115 – 300 nm (vacuum, purging) 190 – 3200 nm, 2.5 – 25 µm
ISO/DIS 24013 Phase Retardation of Guiding Mirrors (AOI 45°)	10.6µm

In the field of optics characterization, the LZH is involved in the measurement and testing of the optical and mechanical properties by applying specially adapted methods. The measurement techniques described below can be offered as a service to interested companies and institutes.

Laser components are basically characterized by the spectral transmittance and reflectance (T&R) and the optical losses, i.e. absorptance and scattering. For the T&R measurement, several spectrophotometers are available capable for testing in the range of 180nm to 25µm according to ISO 15368. Furthermore, a spectrophotometer for the UV/VUV-spectral range has been developed for in-vacuum T&R measurements down to 115nm. Enhanced measurement accuracy is achievable by special laser-based set-ups according to ISO 13697.

For the high-sensitive determination of absorption losses, measurement set-ups according to ISO 11551 were developed and qualified for several important laser wavelengths. The characterization of the total scattering (TS) basing on ISO 13696 is determined by test benches using an Ulbricht-sphere (NIR/VIS spectral range) and a Coblentz-hemisphere (DUV/VUV spectral range), respectively. For the measurement of the absorptance and scatter losses, sensitivity limits in the ppm and sub-ppm can be reached.

The damage handling capability of optical components is of crucial importance for the application of high power lasers. At the LZH, several damage test equipments are available for determining the laser-induced damage threshold (LIDT) for the most prominent laser wavelengths in science and industry. Beside the single pulse damage threshold testing (1-on-1 LIDT, ISO 11254-1), which is mostly applied for basic studies, the more practically important multiple-pulse damage threshold test (S-on-1-LIDT, ISO 11254-2) is typically investigated. From the S-on-1 damage threshold, it is possible to accomplish an extrapolation of the long-term lifetime of optical components. The test standard for assurance of the power handling capability (ISO/FDIS 11254-3), which is presently in the final stage for publication, is intended for a non-destructive proof of a defined intensity level.

For the determination of the non-optical properties of laser components, measurement set-ups are available e.g. for the quantification of particle contamination on optical surfaces (ISO 10110-7). Furthermore, the stability of optical components and especially optical coatings in respect of the extreme environmental conditions (temperature, humidity, mechanical treatment etc.) according to ISO 9211-3 and MIL-C-48497 can be studied.

In the framework of international comparison campaigns (Round-Robin-Tests), the existing test set-ups are regularly evaluated. These investigations are also indispensable for the extension and optimization of the actual measurement standards.