Abstract: A high accuracy periscope assembly is provided. The high accuracy periscope assembly of the invention is comprised of a hollow tubular member and two mirror panels. The tubular member has slanting surfaces at ends thereof and openings to allow light beams to enter, pass through and exit the tubular member. The mirror panels have reflective surfaces for reflecting the light beams and mounting pads for adhering the mirror panels to the tubular member. Alignment pads are also provided which have contact pads and a reinforcement member. The reflective surfaces of the mirror panels are aligned and then the alignment pads secure the mirror panels in their aligned positions without disrupting the kinematic mounting of the structure.

Abstract: A light-weighted optical assembly is provided. The light-weighted optical assembly of the invention is comprised of two members. Each member is constructed of a section and a plurality of ribs extending from the section and comprises one-half of the total thickness of the optical assembly. The members are fused at second ends of the plurality of ribs in a crossing, abutting manner. It is the crossing, abutting fusion of the two members which maintains the rigidity and stiffness of the optical assembly so as to insure against deflection of any reflective surface.

Abstract: This invention relates to lateral transfer retroreflectors having a tubular member comprised of a material having dimensions which are relatively stable with respect to temperature. The retroreflector is further comprised of a roof mirror having two reflective surfaces mounted to one end of the tubular member at three coplanar mounting surfaces of the roof mirror. Mounted on the opposite end of the tubular member is a mirror panel having a reflective surface which is perpendicular to both of the reflective surfaces of the roof mirror. The tubular member has openings for light to pass through and thereby reflect off of the roof mirror and the mirror panel. One of the openings increases the effective aperture of the lateral transfer retroreflector.

Abstract: Pentareflectors have optically flat reflecting plates joined to a base plate so that the reflecting surfaces are at 45.degree. to each other and at right angles to a common reference plane. In the disclosed pentareflector, high accuracy is realized at comparatively low cost through use of an additional unifying plate for holding each reflecting plate in precisely determined adjustment. Bonding material joins the parts together but distortion of the reflecting surfaces commonly caused by the bonding material is here avoided. An error-multiplying adjustment method promotes high accuracy.

Abstract: The disclosed hollow retroflector has three front optically flat reflecting surfaces arranged essentially in orthogonal reference planes, each surface being on a plate having a pivotal axis perpendicular to one of the reference planes and having an adjusting device remote from its pivotal axis for fixing the plate in position that is adjustable about its respective axis. The adjusting device and the means that establishes the pivotal axis cooperate with portions of the plates that are outside the aperture of the retroflector.

Abstract: The disclosed lateral transfer retroreflectors include three flat reflectors, two of them being united at right angles to form a hollow roof reflector, and a third being carried on a central member at the required offset distance from the roof reflector and in a plane perpendicular to each of the first two reflectors. The parts are related to each other in two embodiments which enable adjustment of the planes of the flat reflectors relative to each other without exacting requirements as to right-angled edges of any of the flat reflectors or as to parallelism of end faces of the central member.

Abstract: Known hollow retroreflectors comprise three plates united along joints where the plates abut one another and have reflecting faces oriented to define a hollow reflecting right-angled corner. Yieldable support means for the hollow retroreflector extends from the joints to a supporting structure, and ideally the engagement of the yieldable support means with the hollow retroreflector is confined to said joints.

Abstract: Very large retroreflectors, especially retroreflectors designed for laterally transferring and reversely directing the incoming beam along a parallel but offset outgoing path, are checked for accurate perpendicularity of their reflecting faces. First and second flat, laterally displaced and opposite-facing test reflectors are disposed between an error detector and the retroreflector. To special advantage, the test reflectors are coplanar parts of two pates that are united face-to-face. One test reflector is used to determine its own perpendicularity to the error detector and thereby to determine the perpendicularity of the plane of the second test reflector to the axis of an autocollimator or other error detector. The autocollimator directs its beam toward one end of the retroreflector for lateral transfer and redirection along a reverse path offset from the incoming beam. The second test reflector returns the outgoing beam along what should be an identical but reverse path, to the autocollimator.