Nanosecond Microscopic Measurement of Magnetic Film Switching by Kerr Magneto‐Optic Apparatus

With the use of a laser as the stable high‐intensity light source and a nanosecond‐response photomultiplier tube as a sensing device, nanosecond switching of 25 μm diameter spots in a NiFe film has been measured on a Kerr magneto‐optic apparatus. A sampling oscilloscope is used for examining the switching waveform obtained from the photomultiplier. Because the photon shot noise dominates the photomultiplier output, filtering techniques must be applied to the sampled output. The transient response of the whole system is limited by the anode pulse rise time of the photomultiplier which is a few nanoseconds. Examples of useful data obtained with this apparatus are given. Copyright © 1966 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim