Patent ID: 8310657

Claim:
A method for sensing strain in a component in a wind turbine comprising an optical sensor system with a first optical fiber, a second optical fiber, an optical switch, and a light detector operatively connected by the optical switch with the first and second optical fibers, the first and second optical fibers comprising one or more fiber Bragg grating sensors, the light detector located downstream relative to the one or more fiber Bragg grating sensors of the first optical fiber and downstream relative to the one or more fiber Bragg grating sensors of the second optical fiber, the method comprising: alternately inputting an input optical signal into the first and second optical fibers using the optical switch to provide time division; combining a first transmitted output optical signal from the first optical fiber influenced by the one or more fiber Bragg sensors of the first optical fiber and a second transmitted output optical signal influenced by the one or more fiber Bragg sensors of the second optical fiber from the second optical fiber into a single transmitted output optical; measuring a spectral intensity distribution of the single transmitted output optical signal with the light detector; and processing the measured spectral intensity distribution in a control unit in order to establish a value of a strain in the component.