Photothermally modulated readback from a magnetic tape

The photothermally modulated (PM) readback technique is based on the thermal modulation of a recorded magnetic pattern. The PM-readback signal that is detected by a conventional tape recorder head comprises lateral and depth resolved information of the recorded signal. The PM-readback has been studied from homogeneously magnetized tapes and from a sinusoidal track recorded on a CrO/sub 2/ tape. From the signals measured as a function of laser spot position and of modulation frequency the depth and lateral variation of the magnetization has been determined.