Developers and users of EUV-optics need precise tools for the characterization of their products. Often a
measurement accuracy of 0.1% or better is desired to detect and study slow-acting aging effect or degradation by
organic contaminants. To achieve a measurement accuracy of 0.1% an EUV-source is required which provides an
excellent long-time stability, namely power stability, spatial stability and spectral stability. Naturally, it should
be free of debris. An EUV-source particularly suitable for this task is an advanced electron-based EUV-tube.
This EUV source provides an output of up to 300 μW at 13.5 nm. Reflectometers benefit from the excellent long-time stability of this tool. We design and set up different
reflectometers using EUV-tubes for the precise characterisation of EUV-optics, such as debris samples, filters,
multilayer mirrors, grazing incidence optics, collectors and masks. Reflectivity measurements from grazing
incidence to near normal incidence as well as transmission studies were realised at a precision of down to 0.1%.
The reflectometers are computer-controlled and allow varying and scanning all important parameters online.
The concepts of a sample reflectometer is discussed and results are presented. The devices can be purchased
from the Laser Zentrum Hannover e.V.