Eastman-Kodak Company

Ronald E Gerber

David B Kay

Timothy S Gardner

John Charles Brazas, Jr

Edward C Gage

An apparatus for providing a focus error signal, a push-pull tracking error signal, and a differential phase tracking error signal for controlling an application of a radiation beam from an optical source to a data track of an optical storage medium is disclosed. The apparatus includes a transparent substrate arranged between said optical source and said optical storage medium such that said radiation beam passes through said substrate; a grating beam splitter supported by said transparent substrate and having at least six grating elements. The arrangement of the grating elements being selected to produce signals which are particularly adapted to produce signals which are received by a detector array. The detector array responds to these signals to produce the focus error signal and responsive to signals from the first, second, fifth, and sixth detectors to produce the push-pull tracking error signal, and a differential phase tracking error signal.

Laser detector grating unit (LDGU) for producing focus error, a

An apparatus for producing a tilt error signal representative of the tilt of an optical disk is disclosed. The apparatus includes a source of laser light for focusing a laser beam onto the disk and reflecting such beam from the disk, a beamsplitter positioned to receive the reflected light beam and to direct the light beam in a first direction, and a structure for separating the reflected light beam from the beamsplitter into at least four portions and for producing detection signals for each portion. The apparatus further includes circuitry responsive to the detection signals for producing first and second tracking error signals, the first and second tracking error signals being produced by different combinations of the detection signals and both being sensitive to cross-track diffraction, and circuitry responsive to the first and second tracking error signals for producing the tilt error signal.

Tilt error signal producing apparatus using multiple tracking error

An apparatus for providing focus and tracking error signals for controlling an application of a radiation beam to a data track of an optical storage medium is disclosed. The present invention describes a multi-element optical prism used in the optical head, which permits for a single return path, a reduced cross talk between focus and tracking error signals, and a reduced track offset.

Multi-element prism for optical heads

An apparatus for providing focus and tracking error signals for controlling an application of a radiation beam to a data track of an optical storage medium is disclosed. The present invention describes a multi-element optical prism having at least four separator elements with each separator element engaging at least three other separator elements and at least two separator elements surrounding two inner separator elements and engaging each other at spaced apart positions. This apparatus permits a single return path, a reduced cross talk between focus and tracking error signals, and a reduced track offset.

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Rochester, NY, United States of America

Ronald E Gerber