Apparatus for recording/reproducing holographic data

A method of recording information in a holographic information storage medium using a holographic information recording and/or reproducing apparatus comprising a light source, a polarization conversion device, an optical path forming optical system, a focus adjustment optical system, an objective lens, and a 4f relay system disposed on an optical path between the focus adjustment optical system and the objective lens, the method comprising:

• emitting light from the light source;
• forming a signal beam and a reference beam that are orthogonal to each other from the light emitted from the light source using the polarization conversion device;
• separating the signal beam and the reference beam using the optical path forming optical system so that the signal beam and the reference beam proceed along respective paths, and then, to combine the optical paths thereof;
• focusing the signal beam and the reference beam within the holographic information storage medium using the objective lens, to thereby form an interference pattern thereof and to record information in the form of the interference pattern on the holographic information storage medium;
• varying a position of a focus of at least one of the signal beam and the reference beam in a depth direction of the holographic information storage medium using a focus adjustment optical system;
• and
• maintaining a predetermined optical distance between the focus adjustment optical system and the objective lens using the 4f relay system.

A holographic information recording and/or reproducing apparatus for use with a holographic information storage medium, the apparatus comprising:

• an optical system to generate a signal beam and a reference beam, and to separate optical paths of the signal beam and the reference beam to proceed along respective paths;
• a focus adjustment optical system disposed on an optical path of at least one of the signal beam and the reference beam, and to vary the position of a focus of at least one of the signal beam and the reference beam in a depth direction of the holographic information storage medium;
• an objective lens to focus the signal beam and the reference beam within the holographic information storage medium, to thereby form an interference pattern to record information on the holographic information storage medium;
• and
• a 4f relay system disposed on an optical path between the focus adjustment optical system and the objective lens to maintain a predetermined optical distance between the focus adjustment optical system and the objective lens.