HOLOGRAM LASER UNIT AND OPTICAL PICKUP DEVICE HAVING THE HOLOGRAM LASER UNIT

摘要

PURPOSE: A hologram laser unit mounted on an optical pickup device performs accurate record/reproducing operation about the optical disks having a different recording density. CONSTITUTION: A hologram laser unit(1) wherein a light source, a light detector(9), and a hologram element are integrated, is used to a record operation and a reproducing operation. The hologram element includes the first hologram and the second hologram. The first hologram(11) is provided to an area having an effective diameter corresponding to the number of apertures proper to an optical disk(5). The second hologram(12) is provided to an outer part of the first hologram, and compensates a permeability about a light facing an optical disk(5) from a light source. Thereby, the hologram laser unit embodies an optical pickup device which records or reproduces the information of the optical disks having a different thickness by using only one lens, and minimizes a light quantity variation focused on the optical disk.