The optical second-harmonic (SH) wave generated from a crystal-cored fiber under Cerenkov- radiation-type phase matching can be collimated by an axicon and then can be focused by a spherical lens to a diffraction-limited spot. The deviation of the radiation angle of the SH wave or the angle mismatch between the radiation angle and apex angle of the axicon causes spherical aberration. However, because the focusing system using the axicon is sensitive, such a system is not practical enough. A new optical system is proposed that consists of three spherical lenses: biconvex, biconcave, and meniscus lenses. The system can collimate the SH light radiated from the fiber. The new lens system is over corrected for spherical aberration in certain zones. When the radiation angle of the SH wave deviates from the desired angle, the aberration can be compensated by adjusting the spacing between the biconcave lens and the meniscus lens.