Synchrotron micro-XRF study of metal inclusions distribution in potassium dihydrogen phosphate (KDP) induced by ultraviolet laser pulses

Metal inclusions play critical roles in laser-induced damage in large potassium dihydrogen phosphate optics. In this paper, the distribution and variation of copper, zinc and iron were studied by synchrotron X-ray fluorescence spectrometry. The results showed that these metals were reduced quickly with the expansion of damage sites, which indicated that copper, zinc and iron played key roles in the damage procedure. And the distribution of potassium was used to describe the size of each crater which proved that an observable damage site was formed by some smaller pinpoints. The residual metal inclusions would be concentrated at the edge of pinpoints.