Abstract: A method of adjusting the alignment of a sighting device (5) and a member (4) coupled therewith, said member being pivotable in at least one plane about a first pivot axis (3), and at least part (7) of said sighting device (5) being pivotable about a second pivot axis (6). On the pivotable member an apparatus is mounted which provides a parallel beam of radiation shining directly or indirectly on to the pivotable part (7) of the sighting device (5), and being productive of a point image at the viewing end of the sighting device. The pivotable member is moved into a plurality of different angular positions relative to the first pivot axis (3), and, if during these movements the point image is moved beyond a pre-determined tolerance range, the coupling (8) between the pivotable member and the sighting device is adjusted.

Abstract: The invention relates to a compact, high-aperture, catadioptric objective. Such an objective comprises a negative lens, a main mirror disposed on the peripheral area of a surface of this lens, a positive front lens, a counter mirror facing the main mirror and disposed on the central area of a surface of the front lens, and a field lens adjacent to the negative lens.It is an object of the invention to provide a light-weight, low-cost structure for an objective of the above kind, without detoriating the advantageous optical characteristics. This object is achieved by disposing the field lens in spaced relation to the negative lens, while dimensioning the composite objective in such a manner that ##STR1## and1.46<(n.sub.1, n.sub.2)<1.70wherein n.sub.1, n.sub.2 and n.sub.3 are the refractive indices of thefront lens, the negative lens and the field lens respectively; and r.sub.8 and r.sub.3 are the radii of curvature of the adjacent surfaces of the field lens and the negative lens respectively.

Abstract: A device for binocular viewing of residual light in the visible and the near infrared spectrum, comprising an optical input system, at least one singular image intensifier of the non-inverting type, a collimator, two ocular paths parallel with the axis of the device, and an optical output system associated with each ocular path, which is arranged so that a single image inversion is performed in each ocular path.