Detection Of Surface Irregularities On Magnetic Recording Media
Original Publication Date: 1979-Sep-01
Included in the Prior Art Database: 2005-Feb-20
The information density achievable in magnetic recording depends in part on the surface smoothness of the recording medium. Protrusions of magnetic or other material embedded in the surface coating prevent or reduce contact between the surface and the recording head and thereby cause loss of signal or introduce low frequency modulation noise over an area of several bit periods. Such surface flaws can be monitored or detected and evaluated by means of light diffusely reflected from the recording medium, as shown in the figure. This is a noncontact system which can scan large quantities of recording media under dynamic conditions.