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Method and Apparatus for Electronically Scanning a Completed Disk File for Wear and Lubricant Depletion/Accumulation

IP.com Disclosure Number: IPCOM000117194D
Original Publication Date: 1996-Jan-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Meeks, SW: AUTHOR [+2]

Abstract

Disclosed is a simple method for measuring disk carbon wear and lubricant accumulation/depletion in a completed and fully operational disk file. This device uses a P polarized laser beam, incident at Brewster's angle, which is focused with a cylindrical lens into a line focus. The line-focused beam is directed onto a thin film disk, and the reflected beam falls onto an array photodetector. The array is scanned to read out each of the detector elements. As a magnetic slider repeatedly starts and stops on the disk, the lubricant depletion/buildup and/or carbon wear (under the slider rails) may be measured by contrast changes in the differential images. This device is simple and low cost since all scanning is done electronically. Scan speed is at video rates.

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This is the abbreviated version, containing approximately 52% of the total text.

Method and Apparatus for Electronically Scanning a Completed Disk
File for Wear and Lubricant Depletion/Accumulation

      Disclosed is a simple method for measuring disk carbon wear and
lubricant accumulation/depletion in a completed and fully operational
disk file.  This device uses a P polarized laser beam, incident at
Brewster's angle, which is focused with a cylindrical lens into a
line focus.  The line-focused beam is directed onto a thin film disk,
and the reflected beam falls onto an array photodetector.  The array
is scanned to read out each of the detector elements.  As a magnetic
slider repeatedly starts and stops on the disk, the lubricant
depletion/buildup and/or carbon wear (under the slider rails) may be
measured by contrast changes in the differential images.  This device
is simple and low cost since all scanning is done electronically.
Scan speed is at video rates.

      This device uses a low-power (less than 0.5 mW) collimated
laser diode at 780 nm directed through a glass window on top of an
operating disk file.  The laser beam is P polarized and is incident
at Brewster's angle so that the glass plate will have very little
effect upon the measurement.  The laser power output is very
carefully stabilized by means of a feedback loop so that very small
intensity changes may be measured.  The feedback loop consists of the
collimated laser with a linear polarizer.  The polarized beam is
directed onto a beamsplitter and a portion of the beam is used to
stabilize the laser.  The other half of the beam is focused into a 5
mm long line focus by a cylindrical lens, and this beam passes
through a glass window (which covers the disk file) and onto the thin
film disk.  The beam reflects from the surface and illuminates a 6.5
mm long by 2.5 mm wide scanning photodiode array.  As the array...