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 disk reproducing device includes a division element that divides a reflected light reflected and diffracted by an optical disk into a light flux in a central region and light fluxes in end regions; a photodetector that has a central light receiver that receives the light flux in the central region and at least two end light receivers that receive the light fluxes in the end regions, and outputs a light amount signal corresponding to a light amount of each of the received light fluxes; a non-linear processor that receives each of the light amount signals from the central light receiver and the end light receivers, and outputs linear signals and non-linear signals obtained by processing the light amount signals by linear and non-linear arithmetic operations; an equalization processor that receives the linear signals and the non-linear signals and outputs signals each amplified with a predetermined gain; an adder that adds the amplified signals and outputs an equalization signal; a reproduction signal processor that processes the equalization signal and outputs a reproduction signal and an equalization error signal; and a gain controller that receives the equalization error signal and controls an amplification gain of the non-linear signals.

An optical disk reproducing device includes a division element that divides a reflected light reflected and diffracted by an optical disk into a light flux in a central region and light fluxes in end regions; a photodetector that has a central light receiver that receives the light flux in the central region and at least two end light receivers that receive the light fluxes in the end regions, and outputs a light amount signal corresponding to a light amount of each of the received light fluxes; a non-linear processor that receives each of the light amount signals from the central light receiver and the end light receivers, and outputs linear signals and non-linear signals obtained by processing the light amount signals by linear and non-linear arithmetic operations; an equalization processor that receives the linear signals and the non-linear signals and outputs signals each amplified with a predetermined gain; an adder that adds the amplified signals and outputs an equalization signal; a reproduction signal processor that processes the equalization signal and outputs a reproduction signal and an equalization error signal; and a gain controller that receives the equalization error signal and controls an amplification gain of the non-linear signals.

An apparatus comprises a photodetector (PD) that irradiates a disk with laser light and outputs a signal based on a reflected light from the disk, a front monitor that outputs a reference signal based on an emitted light of a laser diode, and a data detection processing unit to which an output signal of the PD is input to generate a reproduction signal. The data detection processing unit includes a reproduction signal adaptive equalizer that outputs an equalization signal by adaptive equalization processing based on the PD output signal, and a laser noise adaptive equalizer that outputs the equalization signal by the adaptive equalization processing based on a laser noise signal, and generates the reproduction signal in which the laser noise is reduced on the basis of an arithmetic operation result of the output of the reproduction signal adaptive equalizer and the output of the laser noise adaptive equalizer.

Provided are an apparatus and a method for generating a reproduction signal with reduced laser noise. There are provided a photodetector (PD) that irradiates a disk with laser light and outputs a signal based on a reflected light from the disk, a front monitor that outputs a reference signal based on an emitted light of a laser diode, and a data detection processing unit to which an output signal of the PD is input to generate a reproduction signal. The data detection processing unit includes a reproduction signal adaptive equalizer that outputs an equalization signal by adaptive equalization processing based on the PD output signal, and a laser noise adaptive equalizer that outputs the equalization signal by the adaptive equalization processing based on a laser noise signal, and generates the reproduction signal in which the laser noise is reduced on the basis of an arithmetic operation result of the output of the reproduction signal adaptive equalizer and the output of the laser noise adaptive equalizer.

Provided are a device and a method which are capable of performing crosstalk-removed high-quality data reproduction from a high-density recording type optical disc. The device includes a photo detector that outputs a readout signal from a reproduction track of an information recording disc, an adjacent track reproduction binary signal supply unit that outputs a binary signal (binary data) which is a reproduction signal of an adjacent track of the reproduction track, a multi-input adaptive equalizer that includes an equalizer unit that receives the readout signal from the reproduction track and an adjacent track reproduction binary signal and outputs an equalization signal by an adaptive equalization process based on an input signal, and a binarization processing unit that executes a binarization process based on the equalization signal and generates a reproduction signal of the reproduction track.

Provided are a device and a method which are capable of performing crosstalk-removed high-quality data reproduction from a high-density recording type optical disc. The device includes a photo detector that outputs a readout signal from a reproduction track of an information recording disc, an adjacent track reproduction binary signal supply unit that outputs a binary signal (binary data) which is a reproduction signal of an adjacent track of the reproduction track, a multi-input adaptive equalizer that includes an equalizer unit that receives the readout signal from the reproduction track and an adjacent track reproduction binary signal and outputs an equalization signal by an adaptive equalization process based on an input signal, and a binarization processing unit that executes a binarization process based on the equalization signal and generates a reproduction signal of the reproduction track.

Provided are a device and a method which are capable of performing crosstalk-removed high-quality data reproduction from a high-density recording type optical disc. The device includes a photo detector that outputs a readout signal from a reproduction track of an information recording disc, an adjacent track reproduction binary signal supply unit that outputs a binary signal (binary data) which is a reproduction signal of an adjacent track of the reproduction track, a multi-input adaptive equalizer that includes an equalizer unit that receives the readout signal from the reproduction track and an adjacent track reproduction binary signal and outputs an equalization signal by an adaptive equalization process based on an input signal, and a binarization processing unit that executes a binarization process based on the equalization signal and generates a reproduction signal of the reproduction track.

Provided are a device and a method which are capable of performing crosstalk-removed high-quality data reproduction from a high-density recording type optical disc. The device includes a photo detector that outputs a readout signal from a reproduction track of an information recording disc, an adjacent track reproduction binary signal supply unit that outputs a binary signal (binary data) which is a reproduction signal of an adjacent track of the reproduction track, a multi-input adaptive equalizer that includes an equalizer unit that receives the readout signal from the reproduction track and an adjacent track reproduction binary signal and outputs an equalization signal by an adaptive equalization process based on an input signal, and a binarization processing unit that executes a binarization process based on the equalization signal and generates a reproduction signal of the reproduction track.

A cross section of a luminous flux of returning light from a disc is split into a plurality of regions, and an operation is performed so that a weighting of a light amount of a region which has favorable symmetry in a radial direction and is formed on a circumference of an ellipse among the split regions is increased. Further, a lens shift detection signal is formed, and a lens shift detection signal is canceled from a push-pull signal.