Patent ID: 8346032

Claim:
Optical fiber sensor for a temperature-compensated measurement of a deformation in a mechanical component, comprising: a first measurement fiber which is connected at at least two points to the mechanical component and is changed together with the mechanical component at least partially in its length and a second measurement fiber which either is attached loosely to the mechanical component or is connected at at least two points to the mechanical component and is changed together with the mechanical component at least partially in its length; a first optical transmitter fed by a signal generator to generate a modulation signal having a modulation frequency and generating an optical measurement signal coupled via a first Y-coupler into the first measurement fiber and into the second measurement fiber; a first optical receiver for receiving an optical measurement signal passed through the first measurement fiber; a second optical receiver for receiving an optical measurement signal passed through the second measurement fiber; means for generating an optical reference signal coupled via a second Y-coupler into a first reference fiber and into a second reference fiber, wherein the first reference fiber and the second reference fiber have different lengths and output signals of the first reference fiber are supplied to the first optical receiver and those of the second reference fiber are supplied to the second optical receiver; an optical changeover switch for switching the first optical transmitter to either the measurement fibers or the reference fibers; and an evaluation unit which determines a first phase difference from the signals of the first optical receiver and of the second optical receiver while feeding-in measurement signals from the measurement fibers and also a second phase difference while feeding-in reference signals from the reference fibers and outputs a measurement value determined from the first phase difference and the second phase difference.