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With a linear flying height measurement system, the ABS shape should not change as a function of flying height or pitch. To test MicroPhysics new FHT system, we measured a number of points along one rail of a two-rail glide head at a variety of spindle speeds. This type of head was chosen to provide linearity data over a large range: 4 to 175 nm.
Magnification of the low-flying height region is provided below:
We replot this data as flying height vs point location, effectively showing the slider shape in the flying height profile at various spindle RPM values.
This plot shows 1 HGA measured 1 time at each of 9 different spindle speeds. The 9 points are spaced 0.1 mm apart.
We remove the slope and offset by subtracting a simple linear fit to each set of 9 points
Data from 9 spindle speeds after subtracting linear fit
The above plot shows the maximum deviations from average of overlaid data. This is the envelope of the data after subtracting the average slider shape. Also shown below each point is the range of flying heights that correspond to each measurement point. For example, point Crn1 had flying heights from 4 to 19 nm while point Crn9 had flying heights from 57 to 191 nm.. The average deviation ( 9 points x 9 speeds) = 1.4 Angstroms which includes not only linearity, but also repeatability effects.
Above, the standard deviations of the data are plotted. The pooled standard deviation is 2.0 Angstroms. We believe that this level of linearity has never been previously demonstrated. Furthermore this was done at flying heights down to 4 nm with no retract calibration required. This new flying height tester may be the answer to your concerns about measurement accuracy and correlation for low-flying sliders. Please contact us for more information.
Specifications subject
to change without notice or obligation.
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Guzik Spinstand Helium/Altitude Chamber
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