Abstract: 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.

Abstract: A rigid cylinder is provided with small perforations to permit the entry of hydrocarbon containing liquids, gases or vapors, and the interior of the cylinder is lined with a sensor material which expands in the presence of hydrocarbons. The interior chamber enclosed by the sensor material is completely filled with an incompressible liquid, and one end of the chamber is sealed by a conventional pressure sensor so that the presence of hydrocarbons causes the sensor material to exert a pressure upon the incompressible liquid to create an output signal in the pressure sensor. A double-chambered device, with only one chamber being perforated and thereby exposed to the hydrocarbons, can be used to compensate the pressure sensor signal for ambient pressure or temperature changes.

Abstract: An optical fiber sensor for inducing a microbend in an optical fiber in the presence of a detectable fluid such as water includes a chamber with an expansible block located therein. When water enters the chamber, the block expands 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. A gap may initially be provided between the expansible block and the pusher bar so that the presence of water vapor within the chamber will not move the pusher bar but the presence of liquid water will.