Substrate Alignment Through Detection of Rotating Timing Pattern

A recording system for recording data to a rotatable substrate, the recording system comprising:

• a support mechanism configured to rotate the substrate about a central axis;
• a write element configured to write features to the substrate during said rotation;
• a detector adjacent an outermost perimeter of the substrate configured to detect a circumferentially extending timing pattern on the substrate which extends at a fixed radius from a center point of the substrate;
• and
• a control circuit configured to determine an offset value indicative of a displacement distance between the central axis of the support mechanism and the center point of the substrate responsive to two opposing cross-over transitions of the timing pattern detected by the detector over a full revolution, the control circuit further configured to adjust a position of the write element to write a feature to the rotating substrate responsive to the offset value.

A substrate comprising:

• a planar recording surface having a center point;
• an optically detectable, circumferentially extending timing pattern which extends at a constant radius from the center point along an outer periphery of the planar recording surface;
• and
• a plurality of features written to the planar recording surface within the timing pattern during rotation of the substrate about a central axis offset from the center point, at least one of the features from the plurality of features comprising a composite feature written by combining sub-features written to the planar recording surface over multiple passes in which the substrate is separately mounted for rotation about the central axis.