An algorithm for the characterization of surface crack by use of dipole model and magneto-optical non-destructive inspection system

Leakage magnetic flux(LMF) is widely used for non-contact detection of crac ks. The combination of optics and LMF offers advantages such as real time i nspection, elimination of electrical noise, high spatial resolution, etc. T his paper describes a new nondestructive evaluation method based on an orig inal magneto-optical inspection system, which uses a magneto-optical sensor , LMF, and an improved magnetization method The improved magnetization meth od has the following characteristics: high observation sensitivity, indepen dence of the crack orientation, and precise transcription of the geometry o f a complex crack. The use of vertical magnetization enables the visualizat ion of the length and width of a crack. The inspection system provides the images of the crack, and shows a possibility for the computation of its dep th.