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Glide Testing using a Laser-Doppler Vibrometer/Interferometer

IP.com Disclosure Number: IPCOM000113898D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Meyer, DW: AUTHOR [+3]

Abstract

A method and apparatus is described that allows conventional sliders to be used for single-disk glide testing without the need for attaching piezoelectric or other sensors to the slider, suspension, or mount block. A benefit of combining a vibrometer and interferometer is the ability to sense head-disk contact while monitoring the head-to-disk spacing.

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This is the abbreviated version, containing approximately 81% of the total text.

Glide Testing using a Laser-Doppler Vibrometer/Interferometer

      A method and apparatus is described that allows conventional
sliders to be used for single-disk glide testing without the need for
attaching piezoelectric or other sensors to the slider, suspension,
or mount block.  A benefit of combining a vibrometer and
interferometer is the ability to sense head-disk contact while
monitoring the head-to-disk spacing.

      The method proposed for single disk glide testing is to use a
Laser-Doppler Vibrometer (LDV) to measure the slider body ringing
frequencies as is currently done with sliders equipped with
piezoelectric heads.  These slider modes are higher than the
air-bearing modes which are typically in the 10-200 kHz range.  The
slider body frequencies are typically above 200 kHz.  By monitoring
the slider body modulations, actual contact situations can be
discriminated from non-contact excitation of the air-bearing.

      The laser-doppler vibrometer uses the doppler principle in
conjunction with interferometry to measure the normal velocity
difference between two moving surfaces as well as the physical
spacing.  The Figure illustrates a typical Direct Access Storage
Device (DASD) application, where two laser probes are placed at
different locations (one on the slider and one on the disk).  The
light from each of the probes is then recombined and the intensity is
measured using a photomultiplier.  The electrical signal from the
photomultiplier...