DEFECT VISUALIZING METHOD, DEVICE INTENDED FOR ITS REALIZATION AND MAGNETIC FIELD CONVERTER Russian patent published in 1997 - IPC

FIELD: applied magnetooptics; nondestructive tests. SUBSTANCE: problem of visualizing the defects (including latent ones) in articles made of nonmagnetic conducting materials is solved herein. Magnetooptic unit of visualizing of spatially nonhomogeneous magnetic fields is positioned near surface of specimen 13 under test made of conducting material with defect 14. Visualizing unit has pulsed illumination source 1, polarizer 4, magnetic field converter (visualizing member) in the form of film 5 of iron garnet on transparent substrate 6, and analyzer 7. Eddy current are excited in specimen 13 under test with the aid test coil 12 connected to source 10 of alternating or pulse current or means of rotary permanent magnets. Visualizing member is illuminated in synchronism with excitation of eddy current. Magnetic leakage fields are visualized. If defect is available these fields are higher than in case of specimen 13 which has no defect. Visualizing of defect configuration may be based on recording of any parameter of dynamic domain structure and distribution of magnetization in film 5 which is coupled in one-to-one manner with magnetic field acting upon it or has clear threshold. magnetic field converter is made as iron garnet with reduced effective value of gyromagnetic relation. EFFECT: improved visualizing process. 45 cl, 2 dwg