GB901027A - Improvements in or relating to the internal illumination of opaque pressure vessels - Google Patents

Abstract

901,027. Illuminating devices. GENERAL ELECTRIC CO. Ltd. Feb. 23, 1960 [March 18, 1959], No. 9393/59. Classes 75 (2) and 75 (4). [Also in Group XL (a)] A pressure vessel such as a high vacuum apparatus or a vessel enclosing the cores of nuclear reactors having opaque walls 1 is illuminated through a window comprising a cylinder 2 of fused silica, having plane end faces 3, 4 perpendicular to its axis, the cylinder having a length such that (by internal reflection from its polished curved surface) a cone of light incident on the outer end face 4 emerges from the polished inner end face 3 with a vertex angle the same as the incident cone, the cylinder being supported in an aperture in the wall 1 against the pressure forces by contacting bevel portions 5, 7 on the outer end surface 4 and a steel flange 6 held by studs to the wall 1 or being integral therewith. Both end faces 3 and 4 may be polished. The window is used in combination with a linear light-source, e.g. a high-pressure mercury vapour discharge tube, lying along the axis of an ellipsoidal reflector 13 about the position of one focus, the reflector and source being so positioned that the outer end face 4 of the cylinder 2 lies at the second focus of the reflector 13. Within the pressure vessel a prismatic lens 11 is supported at a distance from the end face 3 and has a focal length rather greater than this distance to modify the conicity of the light beam. The cylinder 2 may be long compared with its diameter to project within the vessel and its axis curved with a radius of curvature greater than the diameter of the cylinder so as to modify by internal reflection by the cylinder the direction of the axis of the emergent cone of light so as to illuminate a desired spot within the vessel.