Compatible optical pickup device using a single light source

Abstract

A compatible optical pickup device includes a single light source to emit a light having a wavelength longer than 650 nm, an objective lens having a near axis area, a ring type annular lens area, and a far axis area to focus the light to form light spots suitable for a first relatively thin optical disk and a second relatively thick optical disk to form a first light spot having an FWHM (full width at half maximum) of 0.72 μm or less for the first optical disk and a second light spot having an FWHM of 0.8 μm or more for the second optical disk, an optical path changer to change a proceeding path of incident light, and a photodetector to receive light reflected by the optical disk and having passed through the objective lens and the optical path changer and to detect an information signal and/or an error signal.