GB704285A - Systems and apparatus for the formation of images by total reflection of incident radiation - Google Patents

Abstract

704,285. optical systems. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Nov. 23, 1951 [Nov. 30, 1950], No. 27549/51. Classes 97(1) and 98(1) [Also in Group XL(a)] A system for the formation of images by total external reflection of a beam of incident radiation, particularly for X-rays or neutrons, comprises four concave reflecting surfaces arranged in succession in the path of the beam and juxtaposed in pairs, the reflectors of each pair facing in directions which are mutually at right angles and at right angles to the beam, and the first mirror of the first pair and second mirror of the second pair, and likewise the second mirror of the first pair and first mirror of the second pair extending in. parallel planes but facing in opposite directions. Total external reflection occurs with either crystalline or amorphous surfaces when the glancing angle of the radiation is sufficiently small. The reflectors may be flexible and formed of tungsten carbide or of a layer of tungsten or platinium on a highly polished backing of crystalline quartz or fine tool steel. They may be parabolic cylinders circularly or elliptically cylindrical or if of fixed curvature may be spherical, ellipsoidal or cylindrical. Fig 4 illustrates the arrangement. X-rays from a source 100 and emerging from a collimator 101 impinge upon an object 102 and pass as a beam 32 to fall at glancing incidence on the first pair of reflectors 8, 9 which form a distorted image before the second pair of reflectors 10, 11 arranged as set out above with respect to the first pair. The beam, reflected at glancing incidence is focused by the mirrors 10, 11 to form a distortion-free image 103 on a suitable detector such as a photographic plate or fluorescent screen 104. The reflectors are mounted in the apparatus shown in Fig. 3. The first pair of mirrors 8, 9 are mounted in juxtaposed frames 14, 33 having trunnions 12, 40 respectively rotatable in slides movable for adjustment on a base plate 1. as described below. Sliding within channels 16, 17, in the frame 14 are blocks 18 and 19 separated by a spring 27 and moved together by a screw 22 to press the reflector 8 against a fixed block 20. The reflector is flexible and has a rod 30, Fig. 4, fixed centrally to its front surface and rods 28, 29 fixed to its rear surface, pressure of the block 19 on the rods 28, 29 causing the mirror to bend about the rod 30 to change its curvature. By suitable choice of cross-section the reflector 8 may assume one of the shapes mentioned above. The curvature of reflector 9 is similarly adjustable. The second pair of reflectors 10, 11, are similarly mounted in frames 41 and 65 respectively, mounted on the frame 1 by means of trunnions 43, 73 slidably mounted. As shown for the trunnion 73, the mounting comprises a slidable bearing block 74 moving in a notch 75 and maintained in the desired position by a spring 76 and thumb screw 77. Small rotatory adjustment of the frame 65 about the trunnion 73 is effected by a spring loaded plunger 81. Variation of the curvaure of the reflector 10 is effected by pressing it against a fixed block 52 by two sliding blocks 55, 56 the former connected by studs 60, 61 to a yolk 59 slidable on the frame 41 and having a micrometer adjustment member 62 bearing on the fixed block 52. The reflector 11 is similarly adjusted. Specification 672,816 is referred to.