Fig. 1.

Photographs and scanning electron micrographs (SEM) of uric acid (UA) and calcium oxalate monohydrate (COM) stones before and after laser ablation with Thulium fiber laser in air and water mediums. Direct absorption of IR laser energy by stone in air results in a change from native state to more amorphous state with fusion of stone material, while absorption of IR energy by water contained in pores along stone surface may result in thermal expansion and production of cracks (shown by arrows), contributing to ablation.