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Electron Laser Beam Addressable Memory

IP.com Disclosure Number: IPCOM000077585D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Smith, AW: AUTHOR

Abstract

Electron beam pumped lasing can be obtained in a thin plate of II-VI semiconductors, with the electron and light beams both perpendicular to the semiconductor plate. Thus a two-dimensional raster of lasing spots can easily be generated by scanning and modulating the electron beam. By using CdS, for example, lasing occurs in the visible which is desirable for writing and reading certain types of optical storage media. Power densities of 10/5/W/cm/2/ have been demonstrated in CdS with a 20 mu spot, using an electron beam with a 4 Amp/cm/2/ accelerated to 40Kev. Such a raster of lasing spots can serve as a digital memory with fast, random access.

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Electron Laser Beam Addressable Memory

Electron beam pumped lasing can be obtained in a thin plate of II-VI semiconductors, with the electron and light beams both perpendicular to the semiconductor plate. Thus a two-dimensional raster of lasing spots can easily be generated by scanning and modulating the electron beam. By using CdS, for example, lasing occurs in the visible which is desirable for writing and reading certain types of optical storage media. Power densities of 10/5/W/cm/2/ have been demonstrated in CdS with a 20 mu spot, using an electron beam with a 4 Amp/cm/2/ accelerated to 40Kev. Such a raster of lasing spots can serve as a digital memory with fast, random access.

The essential features of the system are shown in the figure. On the left is a cathode-ray tube (CRT) with a screen of semiconducting material such as CdS. Directly in front of this is a light-sensitive storage film such as a chalcogenide amorphous film or a magnetic film such as a garnet or MnBi. Writing is accomplished on the storage plate using the maximum laser output power. Reading is done at a lower power, using the vidicon on the right to detect the signal transmitted through the storage plate. In the case of the chalcogenide films, writing changes the transmission of the film (amorphous to crystalline transition). In the case of the magnetic films, writing changes the direction of magnetization in the illuminated spots, and this causes a change in the Faraday rotation of the li...