OPTICAL INFORMATION RECORDER/REPRODUCER, OPTICAL INFORMATION RECORDING/REPRODUCING METHOD AND CONTROL CIRCUIT

摘要

Constitution A distance control circuit (23) keeps constant the distance between a condensing member (11) and the surface of an optical disk (1) using return light from a region where near field light is generated. Under that state, a focus control circuit (27) focus-controls the focus position of the near field light to sustain it at the position of an information layer using reflection light from the information layer. Consequently, information can be recorded and reproduced stably with the near field light without causing erroneous erasure or destruction of information recorded on the information layer (2) even if locally varying irregularities occur on the surface of the optical disk (1) or uneven thickness exists in the protective layer (3).