Method for sensing temperature, pressure and liquid level, and variable ratio fiber optic coupler sensors therefor.

摘要

Method of sensing a parameter in a hazardous environment uses a fiber optic coupler sensor having a plurality of input optical fibers (13,16) and a plurality of output optical fibers (14), the cores of the fibres being fused in a waist region which is encapsulated in a material (11) having a refractive index variable with stress. The method may be used for sensing temperature, pressure or liquid level. An array of such sensors may be employed. The method is applicable in particular to fuel tanks.