762,804. Anamorphotic optical systems. NAAMLOOZE VENNOOTSCHAP OPTISCHE INDUSTRIE DE OUDE DELFT. June 10, 1954 [June 10, 1953; June 29, 1953; July 11, 1953; Sept. 23, 1953; Sept. 29, 1953; May 6, 1954], No. 17156/54. Class 97(1) An anamorphotic system for use before a camera or projector objective comprises a concave and a convex cylindrical or toncil reflecting surface so arranged that an incident beam is reflected from one to the other and with their focal lines approximately in coincidence and axes of generation parallel. The surfaces may be formed on a single prism or two separate prisms and the system may be combined with two plane reflectors, or with another similar system, to avoid lateral displacement of the beam. As showh Fig. 9a the concave and convex , cylindrical reflectors 35, 36 with their axes of generation in the plane of the Figure, are supported in a housing 37, the reflector 35 being mounted on a plate 38 which carries a tube 39 having an external screw thread engaging an internal thread on a knob 40. The latter is provided with an external screw thread screwed into the housing 37 so that on rotation of the knob 40 the mirror 35 is moved axially, means being provided to prevent its rotation. In the system shown the size of the beam is unchanged by the system in the plane of the figure but is reduced in the plane perpendicular thereto. A negative lens may be placed in the emergent beam to enlarge it as a whole. The system 35 and 36 may be rotatable as a whole about an axis perpendicular to the figure or one of the prisms only may be so rotatable. Further means may be provided for rotation about an axis in the plane of the figure. To correct spherical aberration the concave mirror 33, Fig. 8, may be formed on the rear surface of a meniscus lens 32 traversed twice by the beam before it reaches the convex reflector 34. The lens 32 may also extend in to the beam leaving reflector 34. Alternatively the reflector 34 maybe formed on the rear surface of a meniscus lens, which may similarly extend into the beam incident on the reflector 33. Fig. 12 shows a system in which the concave and convex reflecting surfaces 52, 53 are respectively formed on separate glass prisms, carried respectively on mountings 58 and 57 so that adjacent face thereof abut along a plane 56. The mountings 57 and 58 can be moved simultaneously in opposite directions along the plane 56 by a member 59 pivoted at 60 and engaging both mountings the latter being guided by movement of blocks 63, carried thereby, in a slide 64 and the member 59 being rotated by an eccentric 62 operated by an external knob. Thereby the relative position of the re-. flectors 52 and 53 may be adjusted. The system is shown combined with a similar system comprising a concave reflector 54 and convex reflector 55. Alternatively these reflectors may be plane or may be formed on the outer surfaces of a single prism, as may be surfaces 52 and 53. In the modification shown in Fig. 14 the concave surface BC and the convex surface FE are formed on two prisms arranged so that their adjacent surfaces AC, FD are slightly separated by an airspace. A beam incident on the plane entrance face AB is totally internally reflected at the surface AC, is reflected by the concave surface BC, passes through the surfaces AC, FD, is reflected by the convex surface FE, totally internally reflected by the surface FD and emerges through the surface DE. Specifications 354,843 and 356,955 are referred to.