Method for enhancement of spatial resolution of eddy current imaging

Abstract

We propose a method for spatial resolution enhancement of eddy current images obtained by magnetic induction 2D scanning. A measurement technique based on a scanning differential source of an alternating magnetic field combined with a receiver is considered. A flat spiral coil is used as a receiver. The dimensions of the receiver and source coils are larger than or comparable with the dimensions of the objects under study. We represent an electrically conductive object as a set of small diameter conductive coils with a specific current induced by an external source. The method proposed solves the forward and inverse problems for linear coefficients describing the distribution of small coils representing a flat conductive object of arbitrary shape. This method was verified numerically and experimentally. The visualization of the object at a range of 15 mm with appropriate spatial resolution is shown experimentally at a frequency of 30 kHz. This method could be applied for the non-destructive testing and visualization of metallic objects.The novelty of the proposed method lies in the fact that it provides the ability to use probe coils with sizes much larger than inhomogeneities. We also proposed a method for calculating the hardware function of the system and solving the inverse problem. Detailed object visualization with sizes smaller than the probe system of the coils is provided. The possibility of increasing the resolution by seven times at a noise level of 0.1% is shown numerically.