Browse Prior Art Database

Method of Inspection of Magnetic Heads

IP.com Disclosure Number: IPCOM000102070D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Argyle, BE: AUTHOR [+4]

Abstract

Disclosed is a method of optical inspection of magnetic heads on a ceramic block before dicing and polishing operations.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 97% of the total text.

Method of Inspection of Magnetic Heads

       Disclosed is a method of optical inspection of magnetic
heads on a ceramic block before dicing and polishing operations.

      Magnetic heads are manufactured from blocks of ceramic a few
millimeters thick and about 2" square.  The magnetic material, wires,
etc., are deposited on the polished surface of the material.  The
pole piece of a head is shown in cross section in the figure.  The
magnetic material 1 lying in planes parallel to the polished surface
2 of the ceramic 3 can be optically inspected through the transparent
overlying alumina ceramic material 4, but the contoured material 5
lying in a plane roughly 45 degrees to the surface 2 is difficult to
inspect due to the small depth of field at the required
magnification.

      The optical set up shown in the figure would keep the plane 5
in focus at the expense of a variation in magnification across the
field.

      The focal plane of the ordinary objective lens 6 is shown as a
45- degree plane 7 when the inspected surface 5 is at 45 degrees to
the horizontal.  The light impinging on this plane 7 is changed in
direction by a holographic grating 8 so that the light 9 diffracted
in the first order travels approximately perpendicular to the plane
7.  A normal microscope eyepiece with an axis perpendicular to the
plane 7 can now capture this light and bring the plane 7 into focus.
As shown, the magnification of the surface features varies across the
su...