OPTICAL INFORMATION RECORDING APPARATUS PROVIDED WITH MEANS FOR SAMPLING AND HOLDING A SERVO SIGNAL WHEN THE INTENSITY OF A LIGHT BEM IS VARIED

摘要

An optical information recording apparatus comprises a recording device for condensing into a spotlike shape a light beam intensity-modulated between at least two levels which are not zero, scanning the light beam on a recording medium and recording information thereon, a detector for detecting a signal indicative of the position error between the light beam spot and the medium in the focusing direction perpendicular to the surface of the medium or the tracking direction in a plane parallel to the surface of the medium which is perpendicular to tracks formed on the medium, a servo device for correcting the position error on the basis of the detected signal, means for varying the gain of the servo device in conformity with the intensity level of the light beam, and a device for sampling and holding the detected signal as long as at least the intensity of the light beam is halfway of the shift between different levels.