We demonstrate a compact source of ultraviolet single-frequency pulses with high average output power realized by subsequent single-pass frequency doubling and quadrupling of a diode-pumped passivelyQ-switched miniature Nd:YAG ring laser. Pulse widths of 2 ns (full width at half maximum), 20 &mgr;J single pulse energy, and 10 kW peak power are achieved at a wavelength of 266 nm with kilohertz repetition rates. A single-pass energy conversion efficiency of 22&percent; with respect to the fundamental light at 1064 nm and an overall efficiency of 2.8&percent; with respect to the diode pump power are obtained. ©1998 American Institute of Physics.