Compatible optic pick-up device

One kind of compatible optical pickup comprising an optical means for emitting a short wavelength light beam suitable for high density optical disc and at least one long wavelength light beam suitable for at least one low-density optical disk, and for receiving and detecting density low-density optical disc and a light beam reflected by the optical disc, an objective lens for forming a light spot on the high density optical disk and the low density optical disc by a short and long wavelength incident beam focusing, a diffraction means for short output from the optical member by the diffraction wavelength beam according to the wavelength of the short wavelength light beam changes to correct chromatic aberration, and a diverging lens, a long-wavelength beam emitted from the optical member toward the objective lens by refraction, relative to the at least one low-density optical disk to increase the working distance. Accordingly diffraction apparatus capable of reducing a short wavelength beam defocus is generated due to mode hopping. Further, since the objective lens provided in the compatible optical pickup, it is possible to ensure a sufficient working distance, the objective lens with respect to the long wavelength light beam emitted from the light source do not collide with the low-density optical disk.