Hologram reproducing apparatus and hologram reproducing method

A hologram reproducing apparatus which reproduces an information signal by radiating a reference light to a hologram in an optical information recording medium and generating a reproduced light that includes the information signal when the reference light is radiated to the hologram in the optical information recording medium, comprising:

• a division wavelength plate having at least two transmission regions including a first transmission region that surrounds a second transmission region, wherein the reproduced light passing through the first transmission region is polarized by the first transmission region in a direction substantially orthogonal a direction of the reproduced light passing through the second transmission region;
• a prism which reflects the polarization-converted reproduced light that passes through the first transmission region to separate the polarization-converted reproduced light from the reproduced light that passes through the second transmission region;
• a light detector that is disposed to receive the polarization-converted reproduced light which passes through the first transmission region and that is reflected by the prism;
• an imaging element that is disposed to receive the reproduced light which passes through the second transmission region and through the prism to generate the reproduced information signal;
• a servo control circuit that drives movement of the division wavelength plate;
• and
• a servo signal generating circuit that generates a signal based on the polarization-converted reproduced light received by the light detector that is output to the servo control circuit to drive a position of the division wavelength plate so that the entire reproduced light is incident on the second transmission region.