Patent ID: 9653107
Date: 2017-05-16
CPC Classifications: G03H,G11B

Claim:
1. A hologram recording and playback device that emits signal light and reference light and records or plays back information to/from a hologram recording medium, the hologram recording and playback device comprising: a medium rotation unit that rotates the hologram recording medium around a predetermined rotational axis; a movement unit that is capable of moving a position of the medium rotation unit within a plane that is perpendicular to the rotational axis; an orthogonal incident angle change unit that is capable of changing an orthogonal incident angle, at which the reference light is made incident on the hologram recording medium, to a direction orthogonal to an incident surface that includes an optical axis of the signal light and a normal line of the hologram recording medium; a medium rotation control unit that controls the medium rotation unit so as to rotate the hologram recording medium; an eccentricity compensation unit that performs positioning control of the movement unit; an orthogonal incident angle control unit that controls the orthogonal incident angle change unit; and an orthogonal incident angle calculation unit that calculates the orthogonal incident angle, wherein, when the medium rotation control unit controls the medium rotation unit so as to rotate the hologram recording medium, subsequent to performing positioning control of the movement unit by the eccentricity compensation unit, the orthogonal incident angle control unit controls the orthogonal incident angle change unit so as to change the orthogonal incident angle of the reference light on the basis of a calculation result of the orthogonal incident angle calculation unit.