Browse Prior Art Database

Semi Automatic Flight Height Measuring for Magnetic Heads

IP.com Disclosure Number: IPCOM000089120D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Heinrich, V: AUTHOR

Abstract

The head assembly is loaded onto a rotating glass disk and is illuminated through a transparent disk by light of a known wavelength lambda from a variable-frequency monochromatic light source.

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Semi Automatic Flight Height Measuring for Magnetic Heads

The head assembly is loaded onto a rotating glass disk and is illuminated through a transparent disk by light of a known wavelength lambda from a variable-frequency monochromatic light source.

As shown on a CRT display controlled by a camera observing a head and a disk, lambda is manually changed until an interference fringe line appears at the edge of the sliding head. The light intensity then detected at sample points along the edge of the sliding head has a minimum amplitude M and a wavelength lambda(M), as shown in the figure. However, measuring lambda(M) by manually positioning the fringe line to the edge is not sufficiently accurate, since minimum light intensity M cannot be readily determined by the operator.

The semi-automatic apparatus proceeds from the manual adjustment described above, varying lambda, for example, to lower values until the light intensity, i.e., the video signal of the camera, at the edge of the head, has reached a predetermined amplitude A. Wavelength lambda(1) at this amplitude is stored. Then wavelength lambda is again varied, passing through lambda(M) and finally reaching a at the predetermined video signal amplitude A. Subsequently, lambda(2) is also stored and lambda(M) is calculated in accordance with lambda(1) lambda(2) over 2. The flight height d is equal to n . lambda M over 2 (n = 1, 2, 3 ...).

When visible monochromatic light is employed for measuring flight heights ...