Abstract: An optical data storage system comprises an optical data storage medium, a moveable optical head, and a fixed optical system. The fixed optical system comprises a focussing system and a fine tracking system. The fine tracking system achieves displacement of the beam spot on the optical medium without displacing the central axis of the beam from the aperture of the objective lens in the optical head. A low mass optical head is achieved without loss of light at the objective lens.

Abstract: A multiple beam optical system includes a housing which contains a pair of laser diodes and a pair of optical detectors. The lasers produce overlapping beams of light. The housing includes a beam directing and reflecting member which selectively focuses light from one of the lasers to a corresponding optical detector located in the housing and selectively focuses light from the other laser to its corresponding optical detector located within the housing. The individual power of each of the overlapping laser beams is thereby monitored by the separate detectors.

Abstract: The focal range of a focussed laser beam is enlarged with a simple optical stop where the beam has a Gaussian cross-sectional profile. The stop is arranged between the laser producing the beam, and a beam focussing lens system, and it is provided with an aperture of predetermined diameter with respect to that of the laser beam whereby the outer portion of the beam represented by the low intensity skirts of the profile curve is stopped. This arrangement can influence the focal range up to a 75 percent increase over that obtained with the unstopped beam.

Abstract: This optical system permits larger tolerances in mirror facet pitch angles for rotating mirror line scanning apparatus without the use of expensive lenses having toroidal and like complex surfaces or lenses employing elements that have one cylindrical surface whose center of curvature lies on or very near the axis of the scanned surface. A lens system having a negative cylindrical element with its axis perpendicular to the plane of deflection is employed in a rotating mirror scanning arrangement. The lens system images the rotating mirror surface on the scan line in an azimuth perpendicular to the plane of deflection of the beam while ringing the collimated rays of the light source in the plane of deflection of the beam to focus in the one scan line.