Patent ID: 8174699

Claim:
A system for detecting the presence of one or more fluids in a rotating component of a gas turbine engine, the system comprising: a light source that emits light; a first reflector structure coupled to the rotating component, said first reflector structure having a first face and a second face, said first face receiving light from said light source, wherein said first reflector structure: reflects at least a substantial portion of the received light from said light source if said second face is in the presence of a first fluid; and does not reflect a substantial portion of the received light from said light source if said second face is in the presence of a second fluid, the second fluid having an index of refraction that is greater than an index of refraction of the first fluid; and a reflection receiver structure that receives light reflected by said first reflector structure, wherein if said reflection receiver structure receives a first predetermined amount of light reflected by said first reflector structure it can be determined that said second face of said first reflector structure is not in the presence of the second fluid.