GB571567A - Improvements relating to optical condenser systems - Google Patents

Abstract

571,567. Optical-projection apparatus. WRAY (OPTICAL WORKS), Ltd., and WYNNE, C. G. Oct. 14, 1943, No. 16889. [Class 97 (i)] [Also in Group XI] In an optical system comprising a reflector and condenser, the reflector has the form, of parts of one or more conicoids of revolution, as shown an ellipsoid, with the light source 5 at one of the foci F1, the major axis F1, F2 being both the axis of revolution and the optical axis of the condenser 9 which receives light through an aperture 6 located about that axis ; the aperture 6 is placed on the opposite side of the focus F1 at which the light source is placed to a line 10, 11 on the reflecting surfaces forming the boundary between two regions 10, 1, 11 and 10, 17, 18, 11 such that rays originating from the light source 5 incident on either of the two regions is reflected to the other region and thence back through the focus at which the light source is placed, the ray after such double reflection making a greater or lesser angle with the optical axis than does the original ray according to whether the latter is incident on one or other of the two regions of the reflecting surfaces. Such rays are shown by the full line F1, 14, F2, 15, F1, 16, the angle 15, F1, F2 after double reflection being less than the angle 14, F1, F2 made by the original ray with the axis, and by the dotted line F1, 19, F2, 20, F1, 21, F2, 22, F1, 23, the angle 20, F1, F2 after the first two reflections being greater than the angle 19, F1, F2 made by the original ray. Modifications comprise the use of other conicoids of revolution ; in Fig. 2 (not shown) part of the ellipsoid is replaced by a hyperboloid convex to the source of light; in Fig. 3 (not shown) the hyperboloid becomes a plain surface containing the minor axis of the ellipse ; in Fig. 4 (not shown) part of the ellipsoid is replaced by a hyperboloid concave to the source of light; in Fig. 5 (not shown) the common chord of a hyperboloid and an ellipse cuts the optical axis outside the line joining the foci ; in Fig. 6 (not shown) the reflector is made up of sections of paraboloids, such that focus F2 is removed to infinity. Light reflected from the zone 17, 18 at the rear of the reflector is ineffective if the distance between Fl and F2 is great, in which case the reflecting surface is replaced by a spherical mirror having its centre of curvature at F1.