A sensor supported by a head transducer has a temperature coefficient of resistance (TCR) and a sensor resistance. The sensor operates at a temperature above ambient and is responsive to changes in sensor-medium spacing. Conductive contacts connected to the sensor have a contact resistance and a cross-sectional area adjacent to the sensor larger than that of the sensor, such that the contact resistance is small relative to the sensor resistance and negligibly contributes to a signal generated by the sensor. A multiplicity of head transducers each support a TCR sensor and a power source can supply bias power to each sensor of each head to maintain each sensor at a fixed temperature above an ambient temperature in the presence of heat transfer changes impacting the sensors. A TCR sensor of a head transducer can include a track-oriented TCR sensor wire for sensing one or both of asperities of the medium.

An optical disc apparatus includes: a controller configured to acquire information of an access result and access positions on an optical disc when an optical disc drive unit configured to optically access an optical disc optically accesses the optical disc; and a storage configured to store the information acquired by the controller.

An optical disc apparatus includes: a controller configured to acquire information of an access result and access positions on an optical disc when an optical disc drive unit configured to optically access an optical disc optically accesses the optical disc; and a storage configured to store the information acquired by the controller.

An inspection method for a recordable optical disc includes focusing laser light on a recording layer and obtaining a data signal dependent on the laser light reflected by the recording layer. The inspection method also includes determining whether the optical disc includes a defect or not by identifying a first period every second period in the obtained data signal obtained, the first period being a period in which a signal level of the data signal is lower than a predetermined value, and each of the second periods corresponding to an ECC block, and outputting a result of the determination.

An inspection method for a recordable optical disc includes focusing laser light on a recording layer and obtaining a data signal dependent on the laser light reflected by the recording layer. The inspection method also includes determining whether the optical disc includes a defect or not by identifying a first period every second period in the obtained data signal obtained, the first period being a period in which a signal level of the data signal is lower than a predetermined value, and each of the second periods corresponding to an ECC block, and outputting a result of the determination.

An optical disc apparatus is disclosed. The optical disc apparatus includes: a driver configured to rotate an optical disc having a recording surface for data; an optical pick-up configured to emit a light beam to the optical disc rotated by the driver; and at least one processor configured to operate the optical pick-up to focus the light beam emitted from the pick-up unit to perform one of recording and reproducing the data on the recording surface and track curvature of the recording surface within a preset allowable range, and to process the light beam reflected from the recording surface, the at least one the processor further configured to increase the allowable range if it is determined that the focus of the light beam cannot track the curvature of the recording surface in a section of the recording surface.

Systems, methods, devices, circuits for data processing, and more particularly to systems and methods for data processing to identify a defect on a medium.