Inspection method and system using multifrequency phase analysis

A method for performing subsurface defect inspections using eddy currents, the method comprising:

• applying a plurality of multifrequency signals to an eddy current probe;
• generating a plurality of multifrequency response signals from the plurality of multifrequency signals, wherein the plurality of multifrequency response signals are included in a multifrequency response dataset;
• identifying a reference free dataset comprising at least two frequency response signals, wherein the reference free dataset is a subset of the multifrequency response dataset, and wherein the at least two frequency signals comprise distinct frequency ranges;
• mixing the at least two frequency response signals to determine a plurality of processing parameters;
• applying the plurality of processing parameters to the multifrequency response signal dataset to generate a noise-filtered image dataset;
• and
• performing a phase analysis on the noise-filtered dataset;

An inspection system comprising:

• an eddy current probe configured to induce eddy currents in a part, for performing an inspection of the part;
• an eddy current instrument coupled to the eddy current probe, wherein the eddy current instrument is configured to apply a plurality of multifrequency excitation signals to the eddy current probe to generate a plurality of multifrequency response signals;
• and
• a processor configured to analyze the multifrequency response signals from the eddy current instrument by performing a multifrequency phase analysis, to inspect a subsurface of the part.

A computer-readable medium storing computer instructions for instructing a computer system for performing subsurface defect inspections, the computer instructions comprising:

• applying a plurality of multifrequency signals to an eddy current probe;
• generating a plurality of multifrequency response signals from the plurality of multifrequency signals, wherein the plurality of multifrequency response signals are included in a multifrequency response dataset;
• identifying a reference dataset comprising at least two frequency response signals, wherein the reference dataset is a subset of the multifrequency response dataset, and wherein the at least two frequency signals comprise distinct frequency ranges;
• mixing the at least two frequency response signals to determine a plurality of processing parameters;
• applying the plurality of processing parameters to the multifrequency response signal dataset to generate a noise-filtered dataset;
• and
• performing a phase analysis on the noise-filtered image dataset.