The infrared emission from an external-cavity-tapered diode laser is frequency doubled in a 5-mm β-BaB<sub>2</sub>O<sub>4</sub> crystal that is placed in a resonant-enhancement cavity. For a coupled diode power of 535 mW, 100 mW of continuous-wave, second-harmonic power is generated at λ=392 nm. The ultraviolet (UV) beam is measured to have a nearly ideal beam-quality parameter, M<sup>2</sup>≃1, in both meridians even though substantial double refraction is present in the nonlinear crystal. Printing of an array of submicron dots on a phase-change film is demonstrated with this UV beam. Also, by printing on photochemical film we demonstrate that improved film sensitivity is possible when a UV source is used.
© 1999 Optical Society of America
Anish K. Goyal, Jayant D. Bhawalkar, Yves Conturie, Paul Gavrilovic, Yalan Mao, Hong Po, and John Guerra, "High beam quality of ultraviolet radiation generated through resonant enhanced frequency doubling of a diode laser," J. Opt. Soc. Am. B 16, 2207-2216 (1999)