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Magnetostrictive Readout of Magnetic Film

IP.com Disclosure Number: IPCOM000096415D
Original Publication Date: 1963-May-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Anderson, JL: AUTHOR

Abstract

Magnetostrictive dimensional changes of a magnetic film distort a diffraction grating on the film, according to a binary value stored in the film, for optical readout.

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Magnetostrictive Readout of Magnetic Film

Magnetostrictive dimensional changes of a magnetic film distort a diffraction grating on the film, according to a binary value stored in the film, for optical readout.

The magnetic film storage element has a diffraction grating ruled on its top surface. Magnetostrictive distortion of the film varies the pitch of the grating so that optical readout is possible.

With the grating at 45 degrees to the 0 bit value orientation of the film as shown, an interrogating field applied at 90 degrees to the 0 orientation rotates the film magnetization from the 0 bit value orientation to a value nearly parallel to the grating. The same interrogating field rotates film magnetization from the 1 bit value orientation to a value nearly perpendicular to the grating.

Magnetostrictive dimensional changes for the 1 readout are thus at 90 degrees to magnetostrictive dimensional changes for the 0 readout. Light continuously applied to the film thus is diffracted differently for the 0 and 1 bit values.

The arrangement of blocking bars and monochromatic light allows a close control of light direction so that small interrogating fields can provide measurable magnetrostrictive dimension changes. Non-destructive readout is possible with these small interrogating fields.

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