A system and method of detecting damage to a wind turbine blade uses one or more fluorescent optical fibers comprising a fluorescent material having an excitation wavelength that is selected such that the material fluoresces upon exposure to ambient radiation at the wind turbine blade, wherein the one or more optical fibers are operatively mounted within the wind turbine blade such that upon damage to the wind turbine blade at least a part of the optical fiber is exposed at the surface of the blade causing the optical fiber to fluoresce; a light detector for receiving a light signal from one or from both ends of the one or more optical fibers upon excitation of the fluorescent material and outputting a signal based on the light signal; and a controller coupled to the light detector to receive the signal.