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Laser Readout for Magnetic Film Memory

IP.com Disclosure Number: IPCOM000093777D
Original Publication Date: 1966-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Kump, HJ: AUTHOR [+5]

Abstract

Readout of information into an image scanning device from a magnetic thin film is accomplished with a flooding laser beam using the Kerr effect. Addressing of blocks of 10/4/ to 10/6/ bits of information is accomplished with this apparatus.

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Laser Readout for Magnetic Film Memory

Readout of information into an image scanning device from a magnetic thin film is accomplished with a flooding laser beam using the Kerr effect. Addressing of blocks of 10/4/ to 10/6/ bits of information is accomplished with this apparatus.

An electron beam is used to accomplish the recording of the bits of information on thin-film memory device 1. The memory film of the device can be a uniaxial permalloy film having a magnetostriction of approximately 10/-5/ either evaporated or sputtered on a metal substrate. The film has an area of several square inches and a thickness of approximately 500 Angstroms. To provide an operating field bias for the film, device 1 is disposed between sets of Helmholtz coils. When the electron beam impinges on a particular spot of the film the heat from the beam induces a stress in the film.

Such stress causes rotation of the anisotropy which in coincidence with the bias field applied by the Helmholtz coils, results in a magnetization rotation.

Laser apparatus 2 provides a beam of approximately 50 milliwatts which is collimated at 3 into a 1 mm. spot. The collimated beam is passed through a conventional multistage digital light deflector 5. The latter is employed to select the given area of the memory device 1 for readout. Prior to striking device 1, the phase of the collimated beam is corrected by a one-half wave plate 6. The beam is also passed through polarizers 4 and 7 to assure that the pola...