PHOTOTHERMALLY MODULATED PLAYBACK FROM A MAGNETIC-TAPE

A novel method is presented which allows spatially resolved detection of magnetic signals from tapes. The PM-playback signal is generated in the head of a tape recorder by thermal modulation of the magnetizatio n of the stationary tape. The PM-playback has been observed from homog eneously magnetized Fe2O3, CrO2 and ferrochrome tapes and from a sinus oidal track recorded on a CrO2 tape. From the signals measured as a fu nction of laser spot position and of modulation frequency the depth an d lateral variation of the magnetisation has been determined.