Electron mirror measurements of magnetic fields over audio and video heads and tapes

The measurement of magnetic fields over audio and video magnetic recording heads and tapes was achieved with a stroboscopic electron mirror microscope which had some attachments for image scanning and readout of current density distribution at the final screen. The curves obtained were processed on a digital computer. This made it possible to calculate the distribution of magnetic fields at any height over the surface of the specimen. The frequency response curves of audio and video recording heads were measured in the range of 0-10 MHz. The magnetic field distribution of sinusoidal and video recorded signals on the tape was also measured at various heights over the tape.