Abstract: In apparatus for optically reproducing information signals from a record carrier, such as a video disc, and in which a light beam from a source, such as a laser is incident through an objective lens onto the surface of the record carrier and a tracking servo control is provided for adjusting the position of the incident light beam on the record carrier; a time base correction mirror operates on the light beams both incident onto, and reflected from the record carrier, and a tracking servo mirror operates only on the light beam incident onto the record carrier. A beam splitter and quarter wave plate are preferably positioned in the optical path between the tracking control mirror and the time base correction mirror. The apparatus may also include a lens with opposed spherical and cylindrical surfaces in the path of the reflected beam between the objective lens and a signal detection photodiode.

Abstract: Information which is recorded on a record medium is read therefrom by a main beam of radiant energy, such as a main light beam, which impinges and scans the record medium so as to be modulated with the recorded information. An additional beam of radiant energy also impinges upon the record medium, and both the main and additional beams pass through a common objective lens which focusses the beams. The main beam, after impinging upon the record medium and being modulated with the recorded information, is detected. The transmission path of the main beam, and particularly its impinging location on the record medium, is controlled in accordance with the detection thereof. Also, the additional beam is detected after it impinges upon the record medium. The effective focussing position of the objective lens is adjusted in accordance with the detected additional beam.

Abstract: An apparatus for optically reading or playing-back video or other signal information recorded as pits or other variations in a record track on a reflective record medium surface employs a polarized beam splitter by which a laser light beam is split into first and second polarized light beams which are respectively polarized in different polarization directions. The first polarized light beam is directed in a respective optical path so as to be projected against the record track on the record medium surface and reflected from the latter to a photo-detector or -sensor developing an output representing the recorded signal information, while the second polarized light beam is directed, in an optical path spaced from that of the first polarized light beam, so as to be projected against the record medium surface and reflected from the latter to control a servo-mechanism by which, for example, proper focusing or positioning of the first polarized light beam in respect to the record track is maintained.