Patent ID: 8520488

Claim:
An optical pickup device comprising: an optical system comprising a light source; a light-receiving system configured to receive light reflected from a disc to generate an electrical signal; and a light-transmitting system comprising an objective lens facing the disc and a collimating lens disposed behind the objective lens, and is configured to guide light emitted from the light source to the disc and guide light reflected from the disc to the light-receiving system, wherein: the light source forms a beam spot having an oval shape with a long axis and a short axis on an information recording track of the disc, and the light source is disposed such that the long axis is maintained at an angle ranging from 0° to 30° with respect to a radial direction passing through a rotation center of the disc, and when a magnification ratio Mr of light transmission is defined as: Mr=fc/fo, where fc is a focal length of the collimating lens and fo is a focal length of the objective lens, the magnification ratio Mr of light transmission corresponding to a digital versatile disc (DVD) ranges from 5.5 to 6.5 and the magnification ratio Mr of light transmission corresponding to a Blu-ray disc (BD) ranges from 9 to 12.