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Optical Read and Write Devices Using Electro Optical Logic

IP.com Disclosure Number: IPCOM000095586D
Original Publication Date: 1964-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Kosanke, K: AUTHOR [+3]

Abstract

A beam of linearly polarized light 1 is shown in the top drawing passing through a birefringent crystal 2 in either one path or another under the control of electro-optic devices 3a and 3b. With switches 4 and 5 open, beam 1 passes as an ordinary ray over the path lo. If both switches are closed, the plane of polarization is rotated 90 degrees and the beam passes as an extraordinary ray over the path leo. When only one switch is closed, the plane of polarization is rotated 45 degrees so the light becomes circularly polarized. The beam then splits, half passing over the path lo and the other half passing over the path leo.

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Optical Read and Write Devices Using Electro Optical Logic

A beam of linearly polarized light 1 is shown in the top drawing passing through a birefringent crystal 2 in either one path or another under the control of electro-optic devices 3a and 3b. With switches 4 and 5 open, beam 1 passes as an ordinary ray over the path lo. If both switches are closed, the plane of polarization is rotated 90 degrees and the beam passes as an extraordinary ray over the path leo. When only one switch is closed, the plane of polarization is rotated 45 degrees so the light becomes circularly polarized. The beam then splits, half passing over the path lo and the other half passing over the path leo.

Several of these units are combined as shown in the middle drawing to direct light to any two out of five points on the surface of photosensitive material 8. Thus, a system for recording information is realized. With switches 4a and 5a closed, the plane of polarization becomes such that the light beam passes through crystals 2a, 2b and 2c as an extraordinary ray. If switch 4d is closed while switch 5d remains open, the light beam splits in crystal 2d, half passing as the ordinary ray to point 4. The other half passes as the extraordinary ray to point 5.

When the light produces transparent spots on material 8, then this can be arranged at the input side of several units, as shown in the bottom drawing, for reading out the stored information. Beams of polarized light are directed against material 8 at points where information can be stored. The setting of the switches to the electro-optic devices necessary to bring light from any two points back to the same path in which...