Hologram recording and playback device and hologram playback method

A hologram playback method in 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, including

• 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, and comprising:
• a step that the medium rotation control unit controls the medium rotation unit to rotate the hologram recording medium;
• a step that the positioning control of the movement unit is performed by the eccentricity compensation unit;
• and
• a step that the orthogonal incident angle control unit controls the orthogonal incident angle change unit to change the orthogonal incident angle of the reference light on the basis of a calculation result of the orthogonal incident angle calculation unit.