Abstract
A coherent tunable vacuum ultraviolet picosecond source has been constructed by third‐order nonlinear mixing of a broadly tunable picosecond visible source and the fourth harmonic of a mode‐locked Nd : YAG laser in xenon. Tunable radiation in the VUV covering portions of the region from 1180 to 1470 Å and continuously from 1631 to 1946 Å is obtained.