Thermal mechanism of laser-induced damages in KDP crystals

In this paper, the nature of the crystalline phases observed at the surface damage sites resulting from laser irradiation is investigated by X-ray diffraction. The results are compared against new data on thermal decomposition of KDP salt. The damage sites consist of polycrystalline KDP and partially dehydrated phases. The comparison with the thermal decomposition study allows to assign a temperature range to the overall temperature reached by the surface during the damaging process. Finally, the difference between surface damage and bulk damage is discussed.