Fiber optic laser texturing with optical probe feedback control

An apparatus for laser texturing a substrate for a magnetic recording medium, which apparatus comprises:

• a source for emitting a laser light beam;
• a spindle for rotating the substrate during laser texturing;
• a first microfocusing lens positioned proximate a first surface of the substrate through which a first laser light sub-beam is impinged on the first surface;
• a first fiber optic cable having a first end optically linked to the laser light beam source and a second end optically linked to the first microfocusing lens;
• a first optical probe positioned proximate the first surface for detecting a variation in the planarity of the first surface;
• a second microfocusing lens positioned proximate a second surface of the substrate, opposite the first surface, through which a second laser light sub-beam is impinged on the second surface;
• a second fiber optic cable having a first end optically linked to the laser light beam source and a second end optically linked to the second microfocusing lens;
• a second optical probe positioned proximate the second surface for detecting a variation in the planarity of the second surface;
• a third fiber optic cable having a first end optically linked to the laser light beam source;
• and
• a second end optically linked to a beam splitter;
• wherein, the first end of the first and second fiber optic cables are optically linked to the beam splitter, wherein:
• the first end of the first and second fiber optic cables are optically linked to the beam splitter;
• the first microfocusing lens and the second microfocusing lens have substantially the same depth of focus;
• and
• the first end of the third fiber optic cable is optically linked to the laser light source sequentially through an automatic attenuator and an electric shuttle.

A method of manufacturing a magnetic recording medium, which method comprises:

• passing a first laser light sub-beam through a first fiber optic cable and then through a first microfocusing lens to impinge on a first surface of a rotating substrate to texture the first surface of the substrate;
• detecting a variation in the planarity of the first surface during texturing;
• passing a second sub-laser light beam through a second fiber optic cable and then through a second microfocusing lens to impinge on a second surface of the rotating substrate opposite the first surface to texture the second surface of the substrate;
• detecting a variation in the planarity of the second surface during texturing;
• passing the laser light beam from the laser light beam source sequentially through an electrical shuttle and an automatic attenuator to a third fiber optic cable and the third fiber optic cable to a fiber optic beam splitter;
• and
• splitting the laser light beam into the first and second sub-laser light beam.

An apparatus comprising:

• a substrate comprising first and second untextured surfaces;
• a spindle for rotating the non-magnetic substrate;
• and
• means for laser texturing the untextured surfaces of the non-magnetic substrate in response to detecting a variation in the planarity of the untextured surfaces.