Magnetic recording disk having a laser-textured surface

A Direct Access Storage Device (DASD) for reading and storing data, said DASD comprising:

• a magnetic recording disk having a substrate with a substrate surface and a magnetizable film layer on the substrate surface, the film layer having a nominal surface plane for storing magnetically-readable data;
• a magnetic head and means for supporting said head in a selected orientation for generally radial controlled movement relative to said disk;
• said outer substrate surface including an annular data region and an adjacent annular second region including a plurality of spaced-apart bumps each having a largest diametral dimension D.sub.r about a center thereof, said each bump including a depression extending toward said substrate surface to a depth d.sub.p below said nominal surface plane, a central protrusion in each said depression extending to a height h.sub.p above said nominal surface plane, and a peripheral elevation substantially surrounding said each depression and extending to a height h.sub.r above said nominal surface plane;
• said plurality of spaced-apart bumps having their centers separated from one another by a minimum separation distance D.sub.s ;
• and
• the height h.sub.p of each central protrusion being greater than the height h.sub.r of each respective peripheral elevation.

A magnetic recording medium comprising:

• a disk which has a substrate layer with a substrate surface, the substrate surface having a nominal surface plane;
• said disk having a plurality of asperities on the substrate surface;
• each asperity comprising a central protrusion, an annulus-shaped depression circumscribing the central protrusion and a circular rim circumscribing the annulus-shaped depression;
• the central protrusions having a substantially common height h.sub.p above the nominal surface plane, each central protrusion having a center with respect to the nominal surface plane;
• the common height h.sub.p being the highest elevation of the substrate layer above the nominal surface plane;
• each central protrusion being non-annular and uniformly shaped;
• the centers of the central protrusions being substantially uniformly spaced at a distance D.sub.s from one another;
• each annulus-shaped depression having a depth d.sub.p below said nominal surface plane and each respective circular rim having a height h.sub.r above the nominal surface plane;
• and
• each central protrusion having a height h.sub.p which is greater than the height h.sub.r of each respective circular rim.

A magnetic recording medium comprising:

• a disk which has a substrate layer with a substrate surface, the substrate surface having a nominal surface plane;
• said disk having a plurality of asperities on the substrate surface;
• each asperity comprising a dome-shaped protrusion so as to provide the substrate surface of the disk with a plurality of dome-shaped protrusions;
• said dome-shaped protrusions having a substantially common height h.sub.p above the nominal surface plane, each dome-shaped protrusion having a center with respect to said nominal surfice plane;
• the common height h.sub.p being the highest elevation of the stibstrate layer above the nominal surface plane;
• each dome-shaped protrusion being non-annular and uniformly shaped;
• the centers of the dome-shaped protrusions being substantially uniformly spaced at a distance D.sub.s from one another;
• and
• each dome-shaped protrusion being centrally located in and projecting from a substantially annulus-shaped depression in said substrate surface wherein the annulus-shaped depression has a depth d.sub.p below said nominal surface plane and each annulus-shaped depression being circumscribed by a substantially circular rim which has a height which is located between a bottom of the annulus-shaped depression and a top of the dome-shaped protrusion.