Kaman SMU9200 - Manual (Page 16)

SMU-9000 User Manual 13
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Part III: Calibration
Laser Calibration for Small Ranges
The SMU-9000 can be used to measure ranges as small as 0.001
inches with precision and accuracy. For small measurements such
as this, Kaman uses a laser measuring system for final calibration.
Calibration using this degree of precision is recommended for
ranges less than 0.004 inches.
Bipolar Calibration
When performing this type of calibration procedure, the output
voltage will range from a negative voltage for the first half of the
measuring range to a positive output for the second half of the
range. The “Zero” and “Gain” controls will interact with each
other more than normal with this type of calibration.
Consequently, the calibration process will be more iterative.
There are two methods that can be utilized to perform a bipolar
calibration. A basic calibration with both end points being equal
(absolute values) or an alternate calibration that produces a “Zero”
output voltage reading at the mid point of the measuring range.
Either method may be used depending on the user’s preference.
Sample calibration record plots of output voltage versus
displacement for each method of calibration is shown in Figure11.
Note that the plot of the data points in the basic bipolar calibration
chart do not intersect the x-y axis exactly at zero as it does in the
alternate bipolar calibration chart.