Patent attributes
An optical data processing apparatus reads and/or writes data from/on a data storage medium, in which first and second data storage layer are stacked. The apparatus includes: a light detector including at least one photodetector for generating a light quantity signal; a detecting optical system for guiding reflected light beams from a storage layer; and a signal processor for generating a layer sensing signal from the light quantity signal and determining, by the layer sensing signal, the type of data storage medium. The light detector includes a layer sensing photodetector arranged in view of an of an area of the light detector, and further includes a photodetector which is different from the layer sensing photodetector which receives the reflected light beam to generate a focus signal.
