Optical disk reader with means for correcting errors due to eccentricity and time axis variations

摘要

An optical reader for reading information recorded on a disk. The reader includes a mirror and a focussing lens. The mirror surface is alterable by feedback means to shift the point of incidence of a light beam passing through the lens onto the disk. The position of the surface is always selected to allow the light beam to pass through the image side focal point of the lens.