Optical sensor for detecting change in fluidic optical medium - has transmitting and receiving optical fibres directed to provide divergent beam through medium to totally reflecting prism

摘要

The appts. is provided with a metallic case (31) having a central cavity (32) with a plane convex lens (41) mounted on the front (34). A totally reflecting prism (42) is fixed to the plane face of the lens. A protective cap (43) covers and protects the exposed faces of the prism. The cavity extends to the rear where a support (44) receives the ends of two optical fibres (45,46) inside an optical cable (47). The optical fibres are mounted in two parallel bores of a sliding element (49) inside the support. This is moved laterally to place the ends of the fibres at the focal point for the lens. A bolt (50) provides positional locking. Light transmitted through one fibre is reflected by the prism to the other fibre to which measuring circuits are coupled.