Abstract: A laser retroreflector array is provided having an array of cat-eye retroreflectors each with an image forming objective through which the laser beam passes and a partial mirror at the focal plane of the image forming objective. By using the cat-eye retroreflectors to reflect the laser beam, the field of view can be angularly limited so that only one retroreflector in the array at a time reflects the laser beam.

Abstract: A dual aperture, off-axis catadioptic Schmidt objective (40) is formed by symmetrically aligning two pairs of Schmidt objectives (12, 14) on opposite sides of a common plane (x, z). Each objective has a spherical primary mirror (16/18) with a spherical focal plane (44/46) and center of curvature (20/22) aligned along an optic axis (36/38) laterally spaced apart from the common plane. A multiprism beamsplitter (44/46) with buried dichroic layers (81-83) and a convex entrance (48) and concave exit (52a-52f) surfaces optically concentric to the center of curvature may be positioned at the focal plane. The primary mirrors of each objective may be connected rigidly together and may have equal or unequal focal lengths.

Abstract: Apparatus for eliminating beamsplitter generated optical aberrations in a pupil concentric optical system providing a plurality of spatially separated images on different focal planes or surfaces (30, 56). The system employs a buried surface beamsplitter (40, 40') having spherically curved entrance (42) and exit faces (44, 54, 74, 76) which are concentric to a system aperture stop (10) with the entrance face being located in the path of a converging light beam (34) directed thereto from an image forming objective element (12) which is also concentric to the aperture stop.

Abstract: Two mutually coherent light beams (50, 58) formed, for example, from a single monochromatic light source (32) are directed to a reflecting surface (20) of a rotatable object (18), such as a mirror, where they are reflected into imaging optical lens (10) having a focal plane optically at infinity whereby a series of interference fringes (14) will be formed in the focal plane (12) which will translate linearly thereacross in response to angular rotation of the object. Photodetectors (22, 24) are located adjacent the focal plane to detect the fringe translation and outputs a signal in response thereto which is fed to a signal processor (30) which is adapted to count the number of fringes detected and develop therefrom a measure of the angular rotation and direction of the object.

Abstract: A special purpose optical collimator system which generates multiple collimated light beams, with precisely related angular separation of the beams. The system is comprised of a stack of relatively flat plate-like refracted prisms (10.sub.1, 10.sub.2 . . . 10.sub.15) in the form of wedges, each having a specified angular deviation, mounted on top of one another in a fixture (44) which holds the wedges so that they are adapted to operate at minimum angular deviation and thus are relatively insensitive to rotational and angular charges. A collimated source of monochromatic light generated for example by a helium-neon laser (20) and a collimated beam expander (24, 30 and 54) provides a common incident beam (14) to the wedges whereupon a plurality of, for example, equally spaced emergent beams (12.sub.1, 12.sub.2 . . . 12.sub.15) are provided.