Patent ID: 8125215

Claim:
A method of measuring vibrations of turbo-machine rotary turbin blades using an induction sensor in a high temperature environment, the method comprising: placing the induction sensor which comprises a coil winding around a set of magnets in an engine housing such that a face of the induction sensor is positioned in the turbo-machine rotary turbine blade's rotation plane; producing a magnetic field in front of the sensor's face through the set of magnets; generating a measurement signal through the sensor's coil winding as a result of the turbo-machine rotary turbine blade's movement in the magnetic field; amplifying the signal and sending such signal to a computer; and wherein a substantially stable and substantially repeatable magnetic field is created in front of the sensor's face through the set of magnets, the magnets having different magnetic fields and different Curie temperatures, the Curie temperatures of the set of magnets being higher than the high temperature environment and the different between the Curie temperatures of at least two of the magnets being sufficiently different to effect a magnetic field sufficiently stable to induce eddy currents in the turbine blades.