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Browse Prior Art Database

Calibration Disc

IP.com Disclosure Number: IPCOM000121825D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Adley, J: AUTHOR [+3]

Abstract

Described is a calibration disc for use by disc flatness measurement techniques. In addition to providing a flat reference, it also provides a known axial acceleration reference on the same disc. Thus, any changes of the known axial acceleration (due to clamping, age, temperature, etc.) will become apparent when measuring the flat reference portion of the disc.

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This is the abbreviated version, containing approximately 100% of the total text.

Calibration Disc

      Described is a calibration disc for use by disc flatness
measurement techniques.  In addition to providing a flat reference,
it also provides a known axial acceleration reference on the same
disc.  Thus, any changes of the known axial acceleration (due to
clamping, age, temperature, etc.) will become apparent when measuring
the flat reference portion of the disc.

      A disc is fabricated as shown in the figure.  The disc has a
flat region and a region of known axial acceleration. Such a disc has
been fabricated by first distorting a thick disc with a raised
portion and then lapping the raised portion flat or by lapping a disc
cut from a known large radius of curvature mirror and then lapping a
portion flat. This disc is first measured in the flat region and the
zero reference of axial acceleration established.  Next, the known
axial acceleration region is measured and the difference is used to
calibrate the axial acceleration measurement.

      Disclosed anonymously.