We investigate the possibility of improving the beam quality and obtaining high conversion efficiency in nonlinear sum-frequency generation. A 765 nm beam from an external cavity tapered diode laser is single-passed through a nonlinear crystal situated in the high intracavity field of a 1342 nm Nd:YVO 4 laser, generating a SFG beam at 488 nm. The ECDL have M H 2 =1.9 and M V 2 =2.4 and the solid-state laser has M 2 <1.05. Varying the focusing of the 765 nm beam, the conversion efficiency and the beam quality of the generated 488 nm beam change correspondingly. We show that it is possible to improve the M 2 of the 488 nm beam to less than 1.3 while preserving a high conversion efficiency of the SFG process.