Abstract: An optical system for deriving an output signal from a video disc record that is reflective to a reading beam includes means for directing a reading beam along a predetermined optical path to a reading plane and then to a light detector. A reading lens, having a back focal plane, is positioned in this optical path to focus the beam on the storage track of the record which is positioned in the reading plane. This lens also returns energy reflected from the record track along the optical path to the light detector. A mirror, which is displaceable about a reference axis, is disposed across the optical path with such reference axis effectively positioned in the back focal plane of the reading lens. A beam-splitter, also disposed across the optical path, is spaced from the mirror in the direction of the light source in order to deflect reflected energy out of the optical path and toward the light detector.

Abstract: In an optical video disc where the storage track is a succession of cavities or pits alternating with a like succession of lands, these elements ideally have a certain length, determined by the encoding method used. Experience shows, however, that they may in practice suffer unintended length variations giving rise to duty factor error. A compensating change is made to the duty factor of the signal developed in reading the disc in order to obviate spurious components attributable to duty factor error and otherwise the source of distortion in image reproduction.

Abstract: An optical video playback device having a self-compensating focus system Photographic one or more afocal relays for increasing the operating range of such a system.

Abstract: An optical video disc playback system includes a feedback or servo arrangement through which radial beam tracking is maintained by controlled displacement of a mirror about a reference axis. The optical system which controls the reading beam is unique in that displacement of the mirror for tracking registration occasions no motion of the light pattern projected onto a photoreceptor employed for the development of a tracking correction signal and/or the program signal. By maintaining the photoreceptor at a distance from the record medium determined by the parameters of the final lens of the optical system, spurious error signals caused by record eccentricities are obviated.Various optical systems are disclosed, both for achieving variations in the overall physical dimensions of the system and for accommodating displacement of the reading beam for timing corrections in addition to beam displacement for radial tracking correction.