Patent ID: 6201391
Filing Date: 2001-03-13
Classification: G01N

Abstract:
A system for nondestructive testing utilizing nonlinear harmonics techniques to determine degradation within metallic protective coatings affixed to a surface of a workpiece comprising:a. means for supplying a time varying current at a fundamental frequency to a nonlinear harmonic sensor and for outputting a phase reference signal;b. the nonlinear harmonic sensor comprising:i. an excitation coil, positioned in close proximity to a surface of a workpiece having a metallic coating, for generating a magnetic field when supplied with the time varying current;ii. a sensing coil, positioned in close proximity to the surface of the workpiece, for detecting a signal caused by an induced magnetic field in the metallic coating;c. means for amplifying and selecting a portion of the detected signal that represents a harmonic frequency component of the signal and generating an output signal using the phase reference signal; andd. means for displaying the output signal.