FLAW INSPECTION IN NONFERROUS CONDUCTORS USING MAGNETO- OPTIC DETECTION METHODS

A NEW METHOD FOR ACHIEVING VISUALIZATION OF FLAWS IN NONFERROUS CONDUCTORS SUCH AS ALUMINUM IS PROPOSED. LESS DIRECT VISUALIZATION TECHNIQUES, INCLUDING EDDY CURRENT AND DYE PENETRANT TECHNIQUES, ALREADY EXIT. HOWEVER, THESE METHODS ARE TIME CONSUMING AND REQUIRE CONSIDERABLE SUPPORT AND PREPARATION. THE NEW METHOD PROPOSES TO ACCOMPLISH DIRECT VISUALIZATION OF FLAWS IN NONFERROUS MATERIALS USING MAGNETIC GARNET FILMSDETECTORS OF MAGNETIC FIELDS ASSOCIATED WITH EDDY CURRENTS. BY ILLUMINATINF SUCH FILMS WITH PLANE POLARIZED LIGHT AND USING A POLARIZING ANALYZER, THE MAGNETIC DOMAIN SSTRUCTURE OF THE FILM CAN BE MADE DIRECTLY VISIBLE. THAT IS,THE COMPONENT OF THEMAGNETIC FLUX PERPENDICULAR TO THE FILMSURFACE PRODUCES EITHER A DARK AREA, A LIGHT GREEN AREA OR AN INTERMEDIATE "GRAY" VALUE. SINCE THE DOMAINS ARE ALTERED MAGNETIC FIELDS ASSOCIATED WITH EDDY CURRENTS PERTURBED BY FLAWS, A METHOD OF DIRECT VISUALIZATION OF FLAWS MAY BE ACHIEVED.