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Magneto Optical Sensing

IP.com Disclosure Number: IPCOM000096702D
Original Publication Date: 1963-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Fan, GJY: AUTHOR

Abstract

This is a method of sensing digital data by utilizing a magneto optic effect and a frequency sensitive detector.

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Magneto Optical Sensing

This is a method of sensing digital data by utilizing a magneto optic effect and a frequency sensitive detector.

The data is inscribed magnetically on a magnetizable surface. This is effected either as a relatively long magnetic imprint or as a regular series of relatively short flux reversals. In this case, a binary 0 is a long inscription and a binary 1 is a regular series of short flux reversals.

The magnetic surface is rotated in the direction of the magnetic inscriptions. The drum rotates at a constant speed and carries the magnetic information. Polarized light is reflected from the magnetic surface. A polarizer is located in the collecting path and is termed the analyzer. Due to the Kerr magneto optic effect, the magnetization of the drum rotates the plane of polarization of the light in proportion to the direction of magnetization. The analyzer is positioned to pass light as a function of the polarization of the reflected light. Photoelectric devices transform the light into current variations.

By use of the frequency detector to screen signals from the photoelectric devices, digital information is sharply discriminated. The binary 1, which is a regular series of short flux reversals, appears as an alternating current substantially composed of a predetermined frequency. The frequency detector is tuned to pass this frequency. The binary 0, which is a relatively long magnetic inscription, appears substantially as a direct current, whi...