In an optical disc apparatus for reproducing information recorded on a track of an optical disc, an optical head irradiates a light beam onto the track, detects a reflected light reflected by the track, and generates a reproduction signal based on the reflected light. A decoder circuit decodes the reproduction signal, and generates a decoded signal including information recorded on the track. A correlation detector circuit calculates a cross-correlation value between the reproduction signal and the decoded signal. A servo circuit detects a deviation amount of an irradiation position of the light beam onto the track, from the reproduction signal, and controls the irradiation position of the optical head based on the cross-correlation value and the deviation amount.

An optical information recording/reproduction device is capable of appropriately correcting the angle of a reference beam during data reproduction even when a wavelength deviation or an angle deviation in multiplexing and vertical directions of the reference beam occurs in a holographic memory recording medium. The optical information reproduction device has a laser light source that generates a reference beam; an image-capturing unit that detects a diffraction ray to be reproduced from the optical information recoding medium; and an optical detection unit that has at least two light-receiving surfaces and is used for detecting a diffraction ray reproduced by irradiating the reference beam on the optical information recording medium. The device also has a light-shielding unit that shields part of the diffraction ray detected by the optical detection unit; and an error signal calculation unit that generates an error signal from a detection signal outputted by the optical detection unit.

The first, third, fourth, and seventh photosensors are disposed on one side with respect to the centerline, and the second, fifth, sixth, and eighth photosensors are disposed on another side with respect to the centerline. The first and seventh photosensors are positioned between the third and fourth photosensors in the direction parallel to the centerline. The second and eighth photosensors are positioned between the fifth and sixth photosensors in the direction parallel to the centerline. The first photosensor receives overlapped light of the 0th-order light with the +1st-order diffracted light, the second photosensor receives overlapped light of the 0th-order light with the −1st-order diffracted light, each of the third to sixth photosensors receives the 0th-order light, and does not receive the +1st-order diffracted light and the −1st-order diffracted light, and each of the seventh and eighth photosensors receives at least the 0th-order light.

An optical medium reproduction apparatus for optically reproducing an optical medium, including: a detection unit for splitting a cross section of a beam returned from the optical medium into a plurality of regions and for forming respective detection signals; a multiple input adaptive equalizer having a plurality of adaptive equalizer units, wherein the respective detection signals are inputted into the adaptive equalizer units, and the outputs of the adaptive equalizer units are computed to form equalization signals; a binarization unit for binarizing the equalization signals to provide binary data; and an equalization error computing unit for determining an equalization error from equalization target signals provided based on the binary data from the binarization unit and the equalization signals, and providing the adaptive equalizer units with the equalization error as control signals for adaptive equalization.

There is provided an optical medium reproducing device configured to optically reproduce an optical medium including a plurality of tracks formed, the optical medium reproducing device including: an optical filter configured to receive an incident returned light beam from the optical medium, and to spatially and optically form a plurality of signals having different bands in a tangential direction and a radial direction; an arithmetic unit configured to operate the plurality of first signals formed by the optical filter so as to form a plurality of channels of second signals; and an electrical filter configured to individually receive the second signals, and to perform processing to the second signals so as to acquire a reproduced signal.

There is provided an optical medium reproducing device configured to optically reproduce an optical medium including a plurality of tracks formed, the optical medium reproducing device including: an optical filter configured to receive an incident returned light beam from the optical medium, and to spatially and optically form a plurality of signals having different bands in a tangential direction and a radial direction; an arithmetic unit configured to operate the plurality of first signals formed by the optical filter so as to form a plurality of channels of second signals; and an electrical filter configured to individually receive the second signals, and to perform processing to the second signals so as to acquire a reproduced signal.

The first, third, fourth, and seventh photosensors are disposed on one side with respect to the centerline, and the second, fifth, sixth, and eighth photosensors are disposed on another side with respect to the centerline. The first and seventh photosensors are positioned between the third and fourth photosensors in the direction parallel to the centerline. The second and eighth photosensors are positioned between the fifth and sixth photosensors in the direction parallel to the centerline. The first photosensor receives overlapped light of the 0th-order light with the +1st-order diffracted light, the second photosensor receives overlapped light of the 0th-order light with the 1st-order diffracted light, each of the third to sixth photosensors receives the 0th-order light, and does not receive the +1st-order diffracted light and the 1st-order diffracted light, and each of the seventh and eighth photosensors receives at least the 0th-order light.

In an optical disc apparatus for reproducing information recorded on a track of an optical disc, an optical head irradiates a light beam onto the track, detects a reflected light reflected by the track, and generates a reproduction signal based on the reflected light. A decoder circuit decodes the reproduction signal, and generates a decoded signal including information recorded on the track. A correlation detector circuit calculates a cross-correlation value between the reproduction signal and the decoded signal. A servo circuit detects a deviation amount of an irradiation position of the light beam onto the track, from the reproduction signal, and controls the irradiation position of the optical head based on the cross-correlation value and the deviation amount.