DocumentCode :
1199216
Title :
Biquadratic surface fits for two-dimensional interferometric head/tape spacing
Author :
Baugh, Eric ; Talke, Frank E.
Author_Institution :
California Univ., San Diego, La Jolla, CA, USA
Volume :
30
Issue :
6
fYear :
1994
fDate :
11/1/1994 12:00:00 AM
Firstpage :
4188
Lastpage :
4190
Abstract :
A biquadratic surface-fit technique to provide the “calibration envelopes” for monochromatic interference fringe patterns is described. The fringe patterns are recorded using an analog camera and an 8 bit frame grabber. The least-squares method is used to fit biquadratic surfaces to selected intensity extrema. The surfaces then serve as the calibration envelopes needed to calculate the head/tape spacing over a two-dimensional area. The spacing is determined with a one standard deviation uncertainty of ±5 nm. The method is compared to the “unloading” technique on a linear drive using a cylindrical head with the result that the surface-fit spacing is on average 5 nm higher due to differences in the lower envelopes. Sample spacing results for a longitudinally slotted quarter-inch cartridge (QIC) tape head are given, showing tape spacing variations of approximately 15 nm amplitude between the slots at a tape speed of 3 m/s
Keywords :
calibration; least squares approximations; light interferometry; magnetic heads; magnetic tapes; spatial variables measurement; surface fitting; analog camera; biquadratic surface fits; calibration envelopes; cylindrical head; frame grabber; least-squares method; linear drive; longitudinally slotted quarter-inch cartridge tape head; monochromatic interference fringe patterns; two-dimensional interferometric head/tape spacing; unloading technique; Calibration; Cameras; Glass; Interference; Interferometry; Magnetic heads; Multilevel systems; Postal services; Surface fitting; Uncertainty;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/20.334031
Filename :
334031
Link To Document :
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