Electronically adjustable positionsensitive radiation detector, focus-error detection system comprising such a radiation detector, and optical read and/or write apparatus comprising such a focus-error detection system.

摘要

Electronically adjustable position-sensitive radiation detector, focus-error detection system comprising such a radiation detector, and optical read and/or write apparatus comprising such a focus-error detection sytem. A position-sensitive radiation detector (1), which on a plane surface comprises at least two adjacent reverse-biased radiation-sensitive diodes. comprises a bias circuit (20) for establishing differences in the reverse voltages across the diodes in order to adjust the boundary (15) between the radiation-sensitive areas of the diodes. To adjust the position of the boundary (15) relative to the locations where a radiation beam is incident on the detector (1) use can be made of the photoelectric currents generated in the radiation-sensitive diodes by the radiation beams (16;b) for comparing the actual position of the boundary with the desired position of the boundary. The position-sensitive radiation detector (1) is particularly suitable for use in the focus-error detection system of an optical read and/or write apparatus.