Head flying height measuring apparatus

Details Head flying height measuring apparatus Head flying height measuring apparatus

1993-11-05

1995-12-12

Rosenberger, Richard A.

Optics: measuring and testing

By dispersed light spectroscopy

Utilizing a spectrometer

356359, G01B 902

Patent

active

054754887

ABSTRACT:
A high-sensitivity apparatus having simple constitution that measures the flying height of a magnetic head. Light emitted from a white light source 25 is directed to the gap between a disk 23 and a head 21, and subjected to multiple reflection between the disk 23 and the head 21. Reflected light from an opaque object, which may be either the disk 23 or the head 21, is divided into at least three components having respective wavelength regions which are directed to different photodetectors 35, 36, and 37 for the respective wavelength regions. An estimation device 38 estimates the flying height of the head according to the least-square method from the outputs of the photodetectors using functions prepared in advance for the respective wavelength regions, and correlates the disk-head gap and the reflected light intensities detected by the respective photodetectors. Real-time calculation according to the least-square method is performed by means of a table look-up technique or a tracking servo technique.

REFERENCES:
patent: 4593368 (1986-06-01), Fridge et al.
patent: 4630926 (1986-12-01), Tanaka et al.
patent: 5280340 (1994-01-01), Lacey
Edwards, R. B.; "Three-Color Laser Interferometer" IBM Technical Disclosure Bulletin, vol. 16, No. 2 (Jul. 1973) pp. 595-596.
"Automatic Digital Flying Height Tester", Pacific Precision Laboratories, Inc., 1988.
Pochi Yeh, "Optical Waves in layered Media", Wiley-Interscience Publication, John Wiley and Sons, 1988, pp. 83-91.

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