Abstract: The present invention relates in general to an optical video detection system for retrieving recorded information. More particularly, the invention relates to an optical detection system whereby optical means focus a laser beam into a reading spot of an area sufficient to interrogate, simultaneously, a plurality of the light scattering elements in at least two adjacent segments of the spiral track. The reading spot further has a dimension in the longitudinal direction of the track such that the spot is incapable of resolving the recorded carrier. Since the information content of adjacent tracks is substantially the same, averaging of the nonscattered light by a photodetector will provide a useful replica of the baseband signal, that is the video signal, modulated upon the carrier.

Abstract: The invention concerns an optical detection system for retrieving information stored in a record track which effectively constitutes a sequence of light scattering or light deflecting elements. An objective lens, disposed above the record track, forms a reading spot for interrogating the track as it is moved past the spot. A photodetector, also disposed above the track, is located in the far field of the reading spot and outside the cone of focused light established by the lens in forming that spot to monitor the time-varying diffraction pattern of the spot reflected from the interrogated portion of the track. Upon receipt of scattered or reflected light rays, the photodetector derives an electrical signal representative of the stored information.

Abstract: A focus correction system exhibits an enhanced acquisition range by responding to a focus-servo pilot signal recorded on a video disc with the same spatial phase distribution in each turn of a multi-turn information storage track.

Abstract: Processing optical video discs may result in modulation of the duty factor of the pits and lands which constitute a spatial representation of a stored carrier signal frequency modulated with program information. Such modulation of duty factor introduces spurious components that are detrimental to image reproduction if the frequency of the stored carrier signal is not at least twice the highest video frequency component to be reproduced. A correction signal is developed and used to at least partially cancel the effect of such spurious components.

Abstract: A video disc for an optical image reproducing system has a storage track formed of pits alternating with lands along a spiral path. The pit depth introduces a phase change of approximately .pi./2 radians between portions of a reading beam that impinge upon pits and portions that impinge upon lands adjacent the pits.