A rasterscan test procedure [L. Lamaignère et al, Rev. Sci. Instrumen. 78, 103105 (2007)] has been
implemented in order to determine low laser damage density of large aperture UV fused silica optics. This
procedure was improved in terms of accuracy and repeatability. Tests have been carried on several facilities
using several pulse durations and spatial distributions. We describe the equipment, test procedure and data
analysis to perform this damage test with small beams (Gaussian beams, about 1mm @ 1/e, and top hat beams).
Then, beam overlap and beam shape are the two key parameters which are taken into account in order to
determine damage density. After data analysis and treatment, a repeatable metrology has been obtained.
Moreover, the consideration of error bars on defects distributions permits to compare data between these
installations. This allows us to reach reproducibility, a necessary condition in order to share results and to make
reliable predictions of laser damage resistance.