GB865140A - Optical inspection device - Google Patents

Abstract

865,140. Optical apparatus; pyrometers. CANADIAN PATENTS & DEVELOPMENT Ltd. June 16,1959 [June 16, 1958], No. 20628/59. Classes 97(1) and 97(3) An inspection device includes a first tubular member which converges axially towards one end of the member to provide a pinhole inlet to the interior of the member for light, a second tubular member surrounding and spaced from the wall of the first tubular member and converging axially towards that end of the second tubular member which is adjacent the convergent end of the first tubular member for the first and second members in combination to define an annular space, means for supplying gaseous fluid under pressure to said annular space, and means constraining said fluid to flow from said annular space through an outlet provided by the convergent ends of the first and second members and surrounding the inlet provided by the first member. As shown in Fig. 2, the device comprises a tube 21 having a frusto-conical end cap 23 terminating in a pinhole 24 for the entry of light to a lens 35 and prism 36 which deflects the light down to an objective 37, the lens 35 being mounted in a ring 38 provided with axial grooves 39 (Fig. 3). Surrounding the tube 21 so as to define an annular space 30 is a second tube 26 also having a frusto-conical end cap 28. The two tubes are independently mounted by brackets 40 and 41 on a platform 42 and a resilient bellows 44 ensures that vibrations of the outer tube are not transmitted to the inner tube 21. A pipe 46 feeds compressed air through the tube 21 so as to maintain it cool and to keep the pinhole opening 24 clear. Compressed air is also fed by a pipe 45 into the annular space 30 so as to provide further cooling and to keep the outlet 31 clear. The cap 28 is sprayed with water from jets at the end of a pipe 33 and the outer part of tube 26 may be similarly sprayed by jets of water 33a. The device is intended for use in inspecting a body which is positioned in, or comprises a stream of hot gaseous fluid and is particularly adapted for use in enabling a flame in an afterburner structure of an aircraft gas turbine engine to be observed whilst the engine is operating in a test cell. The device may also be used in conjunction with measuring instruments to provide an optical pyrometer for remotely measuring the temperature of an incandescent or light emitting solid or gaseous mass.