Robert A Freese

US Patent:

45698813, Feb 11, 1986

Filed:

Apr 12, 1984

Appl. No.:

6/599647

Inventors:

Robert P. Freese - Lake Elmo MN
Leslie H. Johnson - Hudson WI
Thomas A. Rinehart - St. Paul MN
Richard N. Gardner - Grant Township, Washington County both of MN

Assignee:

Minnesota Mining and Manufacturing Company - St. Paul MN

International Classification:

G11B 900

US Classification:

428213

Abstract:

A multi-layer magneto optical thin film recording medium is disclosed having very high carrier-to-noise ratios (at least 47 decibels) and high rotation angles. A transmission electron microscope photomicrograph (at 200,000 X) of one such medium is shown in FIG. 1. The magneto optic layer is a multi-phase amorphous material having magnetic anisotropy perpendicular to the plane of the thin film produced in a triode vacuum sputtering process at vacuums in the range of 4. times. 10. sup. -3 to 6. times. 10. sup. -4 Torr. Various transparent layers, such as dielectric intermediate and anti-reflective layers and a protective covering layer, are combined with the magneto optic layer and a reflective surface to yield media having enhanced carrier-to-noise ratio and magnetic optic angle of rotation.

US Patent:

45395721, Sep 3, 1985

Filed:

Feb 15, 1983

Appl. No.:

6/466436

Inventors:

William B. Robbins - Maplewood MN
Richard F. Willson - Hudson WI
Robert P. Freese - Lake Elmo MN

Assignee:

Minnesota Mining and Manufacturing Company - St. Paul MN

International Classification:

G01D 1534

US Classification:

3461351

Abstract:

An optical recording medium containing a light-absorbing film of refractory material less than 60 nm thick and selected from carbides of Al, Hf, Nb, Ta, Ti, V, W, and Zr and alloys herebetween, whereupon localized heating of the light-absorbing film enables information storage in the form of localized features in the heated areas which can subsequently be optically detected and can be used as a master information record for replication purposes.