Abstract: A system for determining the deviation of an object from a reference line, in particular for determining the deviation of a guided missile from a sight line extending from the missile launcher to a target, comprises a transmitter assembly at the origin of the reference line and a receiver assembly in the object. The transmitter assembly includes a radiation beam projecting device emitting a radiation beam in the direction of the reference line, this radiation beam being such that in planes perpendicular to the reference line it produces a radiation pattern composed of two elongated narrow radiation strips, which are mutually perpendicular and sweep alternatingly and periodically with a predetermined sweeping frequency over the reference line in directions at right angles to their respective longitudinal directions.

Abstract: A discontinuous wide-angle optic for use in a light receiver or transmitter comprises a partial spherical element having a planar boundary surface superposed on the base surface of a pyramidal facet reflector provided with a plurality of inclined facet surfaces, one for each of a plurality of directions of incidence of light passing through the spherical surface of said spherical element. When used in a light receiver, the spherical surface functions as a positive lens to cause entering light rays to converge toward one of the facet surfaces of the reflector for reflection therefrom into an image plane located at a diaphragm formed on a surface of said partial spherical element spaced from its said planar boundary surface.