Abstract: A system and apparatus is disclosed for retrieving analog or digital information stored on an optically sensed disc. In a preferred embodiment, a video disc is disposed between a flooding light source and a matrix array of photosensitive elements, there being provided optical focusing means so that the illuminated data tracks of the video disc are imaged onto the photosensitive array. Circuitry is provided for sensing output signals from selected elements of the array and in response thereto selecting those elements of the array onto which the selected track (or tracks) is best imaged. In this manner the apparatus of the present invention can provide data track following, conventional data retrieval and parallel simultaneous and sequential data retrieval. Alternative circuitry provides signal stream manipulation to compensate for fluctuations in rotational velocity of the data disc and to provide improved signal-to-noise ratios as well as frequency response enhancement.

Abstract: A system for sensing information located in tracks in various layers or depths of a recording medium. The desired information is electro-optically tracked in three dimensions to provide sensing of the information contained in the multi-layered recording medium.