Imaging of magnetic surfaces by detection of photothermally modulated stray fields

D. Hoppstädter; U. Netzelmann

doi:doi:10.1051/jp4:19947156

Issue		J. Phys. IV France Volume 04, Number C7, Juillet 1994 8th International Topical Meeting on Photoacoustic and Photothermal Phenomena 8 ITMP³ / 8éme conférence internationale de photoacoustique et photothermique


Page(s)		C7-659 - C7-662
DOI		https://doi.org/10.1051/jp4:19947156

8th International Topical Meeting on Photoacoustic and Photothermal Phenomena
8 ITMP³ / 8éme conférence internationale de photoacoustique et photothermique

J. Phys. IV France 04 (1994) C7-659-C7-662
DOI: 10.1051/jp4:19947156

Imaging of magnetic surfaces by detection of photothermally modulated stray fields

D. Hoppstädter and U. Netzelmann

Fraunhofer-Institute for Nondestructive Testing (IzfP), University, Bldg. 37, 66123 Saarbrücken, Germany

Abstract
Images from surfaces of ferro- and ferrimagnetic solids are obtained by photothermal modulation of magnetic properties by a focused laser beam and by measuring the surface stray fields using a sensor coil. The lateral resolution is about 10 µm. The method was applied to a sample consisting of cementite plates in an austenite matrix and to monocrystalline ferrite material for video recording heads. Amplitude and phase images are influenced strongly by external magnetic fields. The signal is increasing slightly as a function of the modulation frequency.