A detection apparatus determines whether a recording layer of an optical disc is at a focal point of an objective lens. The detection apparatus includes an objective lens, a beam splitter, a reflector, a detector, and a servo controller. The reflector and the detector are disposed opposite to each other on two sides of an optical axis of the objective lens, and a normal line of the reflector is perpendicular to the optical axis. The beam splitter is disposed between the reflector and the detector and is located on the optical axis. The servo controller is connected to the detector.

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.

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.

Techniques for performing precise tracking in optical tapes are provided. The techniques include providing and using a servo pattern on an optical tape. The servo pattern includes a first set of parallel physical grooves slanted in a first direction across a width of the optical tape and a second set of parallel physical grooves slanted in a second direction that is different from the first direction across the width of the optical tape. Subsets of the first set of parallel physical grooves alternate with subsets of the second set of parallel physical grooves along a length of the optical tape. Two subsets of the first set of parallel physical grooves separated by one subset of the second set of parallel physical grooves form a servo frame in the optical tape.

Digital optical tape archival storage systems and methods are disclosed. A digital optical tape recorder simultaneously writes data and two or more guide tracks onto an unformatted digital optical tape recording medium. A digital optical tape reader includes a camera and an image processor. The camera captures a two-dimensional image of the digital optical tape recording medium including the data and the two or more guide tracks. The image processor extracts the data from the two-dimensional image based, at least in part, on the guide tracks.

There are provided an optical disk and an optical disk recording method which are capable of stable data reading in a case where a recording linear density is increased. According to an optical disk of the present disclosure, a run-in pattern recorded in a groove track and a run-in pattern recorded in a land track are made different patterns so that no great change is caused in the amplitude of an acquired signal due to interference between adjacent recording patterns, and thus, data may be stably read.

Digital optical tape archival storage systems and methods are disclosed. A digital optical tape recorder may simultaneously write data and two or more guide tracks onto a digital optical tape recording medium. A digital optical taper reader may include a camera comprising an array of detectors to capture a two-dimensional image of the digital optical tape recording medium, and an image processor to extract the data from the two-dimensional image. The camera may capture the two-dimensional image of the digital optical tape recording medium without aligning individual data bits recorded on the digital optical tape recording medium to individual detectors within the camera.

There are provided an optical disk and an optical disk recording method which are capable of stable data reading in a case where a recording linear density is increased. According to an optical disk of the present disclosure, a run-in pattern recorded in a groove track and a run-in pattern recorded in a land track are made different patterns so that no great change is caused in the amplitude of an acquired signal due to interference between adjacent recording patterns, and thus, data may be stably read.

Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: write a plurality of test servo patterns using a plurality of different write settings; select one of the plurality of different write settings based on analyzing the plurality of test servo patterns for mode hop; and write a plurality of final servo patterns using the selected one of the plurality of different write settings.

Digital optical tape archival storage systems and methods are disclosed. A digital optical tape recorder simultaneously writes data and two or more guide tracks onto an unformatted digital optical tape recording medium. A digital optical tape reader includes a camera and an image processor. The camera captures a two-dimensional image of the digital optical tape recording medium including the data and the two or more guide tracks. The image processor extracts the data from the two-dimensional image based, at least in part, on the guide tracks.