Browse Prior Art Database

Magneto Optical Readout Technique

IP.com Disclosure Number: IPCOM000092784D
Original Publication Date: 1967-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Mee, CD: AUTHOR

Abstract

For interrogating magnetic memory element 1, digital light deflector 2 scans polarized light beam 3 by the selective energization of electrooptic switches A and calcite crystals 13. With each deflection of beam 3, the direction of polarization of beam 3, originally polarized as indicated by arrows 4, changes until the beam polarization is that indicated by arrows 5 or 6 when passing through element 1 depending upon the number of deflections.

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Magneto Optical Readout Technique

For interrogating magnetic memory element 1, digital light deflector 2 scans polarized light beam 3 by the selective energization of electrooptic switches A and calcite crystals 13. With each deflection of beam 3, the direction of polarization of beam 3, originally polarized as indicated by arrows 4, changes until the beam polarization is that indicated by arrows 5 or 6 when passing through element 1 depending upon the number of deflections.

Data recorded on element 1 is detected by sensing the rotation or lack of rotation of the beam polarization by such element. To cancel out the effect of the rotation of beam 3 due to deflector 2, Wollaston prism 7 is employed to split the beam into two beams 8 and 9 polarized at 45 degrees in opposite directions relative to beam 3.

A readout signal at terminals 10 is generated by subtracting the outputs of the intensity detectors 11 and 12. Such signal is zero in the absence of rotation or a finite value if beam 3 is rotated by element 1. Switch 13 is controlled by the signals energizing deflector 2 for obtaining a unidirectional differential signal from detectors 1 1 and 12.

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