Multifrequency Phase-Encoded Position Patterns
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2005-Feb-18
Magnetic recording and optical storage systems employ position patterns and detection techniques useful for track-following systems. Each position pattern is generated by the superposition of two or more patterns of different spatial periodicity. The process of superposition is nonlinear (non-additive), e.g., overlapping of black or white regions on a photolithographic mask or the use of saturation magnetic recording to produce a magnetic pattern. Because the detection process is also nonlinear, involving the relative phase of the different spatial periods rather than relative amplitudes, the advantages are: the position patterns are not required to have extreme sharpness or resolution and the adverse effects of noise and distortion in the pattern are reduced.