Patent ID: 8634282

Claim:
An optical information reproducing apparatus comprising: a reference beam providing unit configured to input a reference beam to a reproduction recording area and a peripheral recording area around the reproduction recording area on an optical information recording medium that rotates; a peripheral beam detecting unit configured to pass a reproduction beam reproduced from the reproduction recording area in response to the reference beam and to detect a peripheral beam which is reproduced from an interference pattern by inputting the reference beam to the peripheral recording area; a tracking servo unit configured to analyze optical information of the detected peripheral beam and to maintain a normal tracking position; and a reproduction beam detecting unit configured to detect the reproduction beam which passed through the peripheral beam detecting unit, wherein the peripheral beam detecting unit is configured to separate the peripheral beam from the reproduction beam and the peripheral beam reproduced from the optical information recording medium and comprises: a peripheral beam detector configured to detect the peripheral beam using a beam intensity detection area comprising a first detection area and a second detection area, wherein at the normal tracking position, the beam intensity detected from the first detection area and the beam intensity detected from the second detection area repeatedly increase and decrease with the rotations of the optical information recording medium such that the beam intensity detected from the first detection area is equal to the beam intensity detected from the second detection area regardless of the rotation of the optical information recording medium, wherein the beam intensity detected from the first detection area and the beam intensity detected from the second detection area are monitored by the tracking servo unit at a current tracking position to determine a current tracking state; wherein the current tracking position is adjusted by the tracking servo unit based on the beam intensities as well as a difference in beam intensities of states before and after the current tracking state, and wherein the peripheral beam detecting unit further comprises: a polarizer beam splitter disposed between the optical information recording medium and another beam splitter; a wave plate disposed between the polarizer beam splitter and said other beam splitter; and a reflecting film which reflects the peripheral beam to said polarizer beam splitter, wherein the peripheral beam detector is disposed in an optical path of the peripheral beam which is separated from the reproduction beam by said other beam splitter and then is reflected by said polarizer beam splitter.