Wedo the mapping of disks
using "glide" sliders with PZT sensors
that give a signal from both the rigid body motion
of the slider, i.e. for asperities that have sufficient
stiffness to "move" the slider, and by
using much more sensitive signal from the slider
bending modes. The PZT sensor covers the entire
top surface of the slider and the top electrode
is defined into sections to select particular bending
modes. We choose particular bending modes because
the contact response of some of the lower order
bending modes is not optimal (too low signal to
noise because of low damping, non-monotonic contact
amplitude response with increasing interference.).
To characterize the PZT/slider structure for bending
mode vibrations to improve the fabrication of the
glide sliders, we have used a laser heterodyne interferometer
to image the mode shape of the PZT/slider when we
excite the sensor with a signal at the resonant
frequency of that mode. The image of the mode shape
of a 100% slider with a quadrant PZT sensor is included
below along with the modeled displacement mode shape
and the measured mode shape. We can also characterize
the damping of that bending mode by exciting that
mode using a tone current and measuring the decay
of the displacement. There is also an additional
measurement of the same mode excited by a tone burst
at the resonant frequency to characterize the damping
of that bending mode.
The
PZT/slider configuration
The
quadrant PZT layout
The
modeled displacement for the mode
that represents the 2nd twist about
the width at 710-750 kHz
The
measurement of the mode shape using
the laser heterodyne interferometer
scanning across the slider in 100
um steps across the slider from leading
edge to trailing edge. The measurement
was made to also capture the phase
of the motion relative to the signal
exciting the PZT at the resonance
frequency (709 kHz) so we can tell
the parts of the slider that are moving
up (red) and the parts that are moving
down (blue).
