Patent ID: 7859953

Claim:
An optical pickup comprising: a light source to emit a linearly polarized optical beam; an objective lens to collect and irradiate the optical beam to an optical disc and to receive a reflection optical beam reflected from the optical disc, the objective lens being fixed within an optical path of the optical beam and reflection optical beam; a beam splitter to divide the optical beam and the reflection optical beam; a quarter wave plate to transform the optical beam from the beam splitter into a circularly polarized optical beam and to transform the reflected circularly polarized optical beam into an optical beam perpendicularly polarized with respect to the reflection optical beam; a light detector to receive the divided reflection optical beam; a tunable filter to direct the optical beam to the objective lens and to irradiate the reflection optical beam to the light detector, the tunable filter including a high transmission section to maintain the intensity of both the optical beam and the reflection optical beam through entire surface areas of each of at least two sides of the high transmission section, and a neutral density filter section to reduce the intensity of the optical beam using a difference of polarization directions between the optical beam and the reflection optical beam while maintaining the intensity of the reflection optical beam; and a filter drive section to position the high transmission section or the neutral density filter section of the tunable filter inside the optical path of the optical beam and reflection optical beam, wherein the intensity of the optical beam from the light source and the filter drive section are controlled to emit a predetermined level of the optical beam to the optical disc.