Optical fiber sensor for distinguishing between the presence of liquid and vapor phases of a substance

摘要

An optical fiber sensor for inducing a microbend in an optical fiber in the presence of the liquid phase as distinguished from the vapor phase of a fluid such as water. The sensor includes a chamber with an expansible block located therein, and a thin band is provided about the block of a dimension and tensile strength such that any increase in outward expansive force in the block due to an increase in the presence of the fluid in its vapor phase only will not cause the band to rupture; however, when any liquid enters the chamber, the band will rupture to allow the block to expand in a particular direction to move a pusher bar which, in turn, moves a puller wire to bend the fiber at a location remote from the chamber.