DVD OPTICAL RECORDING/PICK-UP HEAD COMPATIBLE TO CD-RW USING PLATE LENS HAVING DIFFRACTION GRATING STRUCTURE FORMING STEP-TYPE

摘要

PURPOSE: A DVD optical recording/pick-up head compatible to CD-RW using plate lens having diffraction grating structure forming step-type is provided to enhance an optical efficiency by not reflecting a light with 790nm and diffracting a great portion of an optical amount centering around an object lens. CONSTITUTION: A first optical source(31) outputs a first light having a 660nm wavelength. A second optical source(41) outputs a second light having a 790nm wavelength. An optical detector(39) detects information from the first light and the second light reflected from optical disks(8, 90). An object lens(36) is collected to an information recording surface of optical disks(8, 90) corresponding to the first light and the second light. Optical devices(32, 33, 34, 38) transmit the first light and the second light to the optical detector(39).