Patent ID: 7969851

Claim:
A laser converging apparatus comprising: a nonpolarizing hologram element having a first area defined by a numerical aperture corresponding to a thickness of 0.075 to 0.1 mm of a first protective layer of a first disk medium and a second area inside the first area, the second area defined by a numerical aperture corresponding to a thickness of 0.6 mm of a second protective layer of a second disk medium, where the thickness of the second protective layer is greater than the thickness of the first protective layer, the second area having a hologram pattern for diffracting blue-violet laser light into zero order light and high-order diffracted light having the order of primary or higher; an objective lens having the numerical aperture corresponding to the thickness of the first protective layer, the objective lens converging the laser light having passed through a part of the first area other than the second area and the zero order light having passed through the second area onto an information surface on one side of the first protective layer, the objective lens converging the high-order diffracted light having passed through the second area onto an information surface on one side of the second protective layer; and a holder that holds the nonpolarizing hologram element and the objective lens.