Patent ID: 7830140

Claim:
A method of inspecting a test part, comprising: positioning an eddy current probe on a surface of the test part; scanning the test part using the eddy current probe to generate a first signal corresponding to a no lift-off condition of the test part; positioning the eddy current probe at a pre-determined distance from the surface of the test part; scanning the test part using the eddy current probe positioned at the pre-determined distance from the test part to generate a second signal corresponding to a lift-off condition of the test part; processing the first and second signals to estimate an electrical conductivity of the test part; scanning the part using the eddy current probe at a plurality of frequencies to obtain first and second signals corresponding to the no lift-off and lift-off conditions of the part at each of the plurality of frequencies; and obtaining a conductivity depth profile using the first and second signals obtained at the plurality of frequencies.