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Browse Prior Art Database

Disk Spacing Measurement

IP.com Disclosure Number: IPCOM000073667D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Lin, C: AUTHOR

Abstract

This is a technique for measuring dynamic slider to disk spacing for the low-flying heads. This technique uses the interference properties of monochromatic light rays. The setup is shown in Drawing A. The wave-length of the laser source is chosen to suit the flying height range to be measured.

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Disk Spacing Measurement

This is a technique for measuring dynamic slider to disk spacing for the low- flying heads. This technique uses the interference properties of monochromatic light rays. The setup is shown in Drawing A. The wave-length of the laser source is chosen to suit the flying height range to be measured.

Due to the interference properties of monochromatic light rays, fringes will be formed at the spacing between the slider and the disk. By monitoring the intensity variation of the fringe with a detector, the dynamic spacing can be interpreted. The intensity of the fringes varies sinusoidally as a function of spacing which is shown in Drawings B. In this technique the range of operation is between zero and Lambda/4. In the case of 3.39 mu'' laser source, the range is between zero and 33.4 mu as shown in Drawing C.

In the case where the nominal flying height is at 18mu'' a rather linear output can be obtained for small fluctuations in flying height. The calibration curve of intensity vs. spacing can be generated statically for the particular slider/disk system used.

The advantages of the technique are as follows: 1) Light detectors have a high frequency response; 2) Slider surface will not be disturbed since no probe has to be installed in the slider; and 3) Coating thickness will not have a significant effect on the signal.

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