Optical head and optical data recording and reproducing apparatus having the same

An optical data recording and reproducing apparatus comprising an optical head for reproducing data from first and second optical disks which are different from each other in at least one of a base material thickness and an available wavelength, disk discriminating means for discriminating between the first and second optical disks, and drive means for driving the optical head based on a result of the discrimination obtained by the disk discriminating means, the optical head including:

• a first light source for emitting a first light beam, the first light beam being used for reproducing data from the first optical disk;
• an optical system designed to converge the first light beam onto the first optical disk in accordance with a base material thickness and an available wavelength of the first optical disk;
• and
• a second light source for emitting a second light beam, the second light beam being used for reproducing data from the second optical disk,
• wherein an optical path length between the second light source and the optical system is different from an optical path length between the first light source and the optical system, the difference between the optical path length from the first light source to the optical system and the optical path length from the second light source to the optical system compensating a wave-front aberration due to the differences in the at least one of the base material thickness and the available wavelength of the first and the second optical disks, and the optical system is determined so that the second light beam is converged onto the second optical disk.