Method for illuminating adjoining slants of an optical disk having a V-shaped groove

A method of reproducing or recording an optical disk which is provided with a groove having a V-shaped cross section in the radial direction and defining first and second slants and a groove bottom between the first and second slants, said method comprising the steps of:

• providing at least three laser sources creating first, second, and third laser beams independently, the third laser beam having a wavelength that is different from the wavelength of the first laser beam and the wavelength of the second laser beam;
• focusing said third laser beam along said bottom of said V-shaped groove;
• using said third laser beam, following reflection from said optical disk, for focusing control and tracking control;
• conducting said first and second laser beams to an objective lens for focusing said first and second laser beams onto said optical disk substantially parallel to the optical axis of said lens so that said first laser beam is focused on the first slant of said V-shaped groove and said second laser beam is focused on the second slant adjoining said first slant;
• preventing said first and second laser beams from returning to said laser sources after reflection from said optical disc;
• and
• subjecting said first and second laser beams to information reproduction or recording processes separately.