Objective lens for a combination three wavelength disc drive including a blu-ray disc reader and a dvd/cd reader/writer, optical pickup incorporating said objective lens, and a disc drive incorporating said optical pickup

An objective lens to focus a first light beam having a first wavelength onto a first optical disc, a second light beam having a second wavelength shorter than the first light beam onto a second optical disc, and a third light beam having a third wavelength shorter than the second light beam onto a third optical disc, the first, second and third light beams emitted from a light source, the objective lens comprising:

• a first surface through which the first, second, and third light beams emitted from the light source enter the objective lens, the first surface including a first diffractive surface;
• and
• a second surface through which the first, second, and third light beams exit the objective lens and proceed toward the three corresponding optical discs,
• wherein the first diffractive surface provides focus control in accordance with (i) 0th order light of the first and second light beams which are respectively focused onto the first and second optical discs, and (ii) 1st order diffracted light of the third light beam which is focused onto the third optical disc.