Apparatus for recording/reproducing holographic information

An adjustment optical system of a holographic recording and/or reproducing apparatus, the adjustment optical system comprising:

• a first adjustment member to set focal positions of a signal beam and a reference beam emitted onto a holographic information storage medium;
• a second adjustment member to adjust a path difference between the signal beam and the reference beam so as to compensate for a path difference between the signal beam and the reference beam;
• and
• a polarization separation device to separate the signal beam and the reference beam into a first path for the signal beam and a second path for the reference beam based on a polarization of the signal beam and the reference beam, so as to direct the signal beam to the first adjustment member and the reference beam to the second adjustment member.

A polarized light forming optical system of a holographic recording and/or reproducing apparatus, the polarized light forming optical system comprising:

• a first polarization changing device to change light emitted from a light source into a first polarized beam and a second polarized beam orthogonal to the first polarized beam;
• a first optical path changer to separate the first polarized beam and the second polarized beam;
• a first mirror to bend a path of the first polarized beam and a second mirror to bend a path of the second polarized beam so as to cause the first polarized beam to intersect the second polarized beam at a second optical path changer;
• a first half wave plate and a second half wave plate arranged on one of the paths of the first polarized beam and the second polarized beam and arranged at different sides of the second optical path changer, to convert the first polarized beam or the second polarized beam into another polarized state so as to cause the first polarized beam and the second polarized beam to be transmitted from the second optical path changer in an identical polarization state;
• and
• an optical path combining unit to combine the paths of the first polarized beam and the second polarized beam after the first polarized beam and the second polarized beam are transmitted from the second optical path changer;
• wherein one of the first polarized beam and the second polarized beam is a signal beam and the other of the first polarized beam and the second polarized beam is a reference beam.

A holographic recording and/or reproducing apparatus, comprising:

• a first light source;
• a polarization forming optical system to form a polarized reference beam and a polarized signal beam having orthogonal polarizations from light emitted by the first light source;
• a focusing optical system to focus the polarized reference beam and the polarized signal beam on an identical surface of a holographic information storage medium so as to record information via an interference pattern;
• and
• an adjustment optical system to adjust a path difference between the polarized reference beam and the polarized signal beam so as to compensate for the path difference between the signal beam and the reference beam.