Apparatus for sensing temperature and/or strain in an object

摘要

Apparatus for sensing temperature and/or strain in an object includes a broadband light source (1), connector means (2) in the form of an optical circulator or an optical coupler to which at least two substantially identical optical fiber Bragg gratings (4, 5) are connected. Grating (4) receives the broadband light from the connector means (2) and functions as a sensor of temperature and/or strain in an object. Light is reflected back from the grating (4) to the connector means (2) and then passed to the grating (5) which acts as a reference grating through which a light output signal is transmitted to a detector (8) which is conveniently a photodetector. Means are provided for chirping the two gratings (4, 5) at the same bandwidth and the detector (8) measures the intensity of the received light output signal, with the intensity being monotonically related to the change in temperature and/or strain sensed by the grating (4) in the object.