Apparatus for measuring the flying height and orientation of a m

Details Apparatus for measuring the flying height and orientation of a m Apparatus for measuring the flying height and orientation of a m

1996-10-24

1998-08-04

Le, Que

Radiant energy

Photocells; circuits and apparatus

With circuit for evaluating a web, strand, strip, or sheet

25055928, 356375, G01N 2186

Patent

active

057897565

ABSTRACT:
The invention provides an apparatus for measuring the flying height and orientation of a magnetic head (54) relative to a transparent disk (20) based on frustrated total internal reflection. The apparatus comprises a housing (10) that mounts an electric motor (12) which rotationally supports the aforementioned disk. The disk (20) has a tapered lateral surface (20c) with light emitting means (22) such as a laser(24) installed on one side of the disk lateral surface and a light detecting means (30) on a side of the disk diametrically opposite to the laser. The light is emitted from the laser (24) and is directed to the disk (20) perpendicular to the tapered lateral surface (20c) of the disk (20). The latter has a tapering angle of 45.degree. so that the light is propagated through the body of the disk (20) in the channel region (49) with total internal reflection from two parallel surfaces (20a and 20b) of the disk into the body of the disk. As a result, when the magnetic head (44) to be tested is absent, the light detecting means (30) shows an area of homogeneous intensity of the reflected light. When, however, the magnetic head (44) approaches to the surface (20a) of the disk and is supported during rotation of the disk at a flying height, i.e., on an air cushion, the proximity of the head frustrates the total internal reflection. As a result, the intensity of the reflected light sensed by the detector (38) is reduced. The degree of this reduction can be translated through appropriate electronic means and computer (40) into the value of the flying height.

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