Investigation on tape-head contact in VTR

This paper describes the tape-head contact, especially the spacing between the tape and the head in video tape recorder (VTR) from the view point of tape surface roughness. The spacing was measured by optical interference method, and the surface roughness, by optical noncontact microsurface measurement system. As the result 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 0 level) value of the tape. Based on this result it is assured that the output voltage of so-called ME tape is larger than that of MP tape by only about +2 dB at the wavelength Lambda = 0.49 micrometer except for the spacing effect caused by the tape surface roughness.