To allow us to fly at close spacing
to the disk we need to control the disk
micro-waviness because it excites slider
spacing modulation. The images below
are the images of the micro-waviness
measures in a bandpass from 50um - 1mm
that we think is relevant to the slider
spacing modulation. The micro-waviness
has been measured for the entire disk
surface and shows that the disk can
have local micro-waviness significantly
higher than average across the disk
surface. The data is top to bottom from
OD to ID ~31mm to ~14 mm and for the
full 360 degrees around the disk.
[The
images are generated from by scanning
a laser beam (~ 15 um diameter) from
a laser heterodyne interferometer across
the disk surface. The data is averaged
over 25 disk rotations for each radial
scan.] |
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| Here
is a image of the entire disk
with a small section bounded by
the cursors at the upper left
of the image. |
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| This
image has the box reduced to one
track so that the averaging of
the heights within the box doesn't
reduce the peak amplitude of the
local micro-waviness on the disk. |
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