Investigation on tape-head contact in VTR

Describes the tape-head contact, especially the spacing between the tape and the head in video tape recorders (VTRs), from the viewpoint of tape surface roughness. The spacing was measured by the optical interference method, and the surface roughness by an optical noncontact microsurface measurement system. The spacing, obtained by the phase-shift correction of the reflected light, is found to be equal to the surface roughness P-O (peak to O level) value of the tape. This assures that the output voltage of metal evaporated (ME) tape is larger than that of metal powder (MP) tape by only about +2 dB at the wavelength w=0.49 μm except for the spacing effect caused by the tape surface roughness