Optical information recording/reproducing method and apparatus in which a first optical spot performs focusing, tracking, erasing and recording and a second optical spot performs two reproducing modes

摘要

An optical information recording and/or reproducing apparatus includes an optical system for letting first and second optical beams pass through substantially the same optical path to form first and second optical spots on the same information track on a surface of an information recording medium and for guiding reflected light from the surface of the information recording medium to photo sensors to detect recorded information in the information recording medium. The first optical spot is used for focusing error detection, tracking error detection, erasing of old information, and recording of new information. The second optical spot is used both for reproduction-while-recording of newly recorded information and for normal reproduction of recorded information. The first optical spot advances and the second optical spot follows on a moving information track.