Large capacity digital memory

Abstract

Abstract A METHOD AND APPARATUS ARE DISCLOSED FOR FORMING A PAGE-ORGANIZED OPTICAL MEMORY THAT CAN BE READ BY A SINGLE ARRAY OF PHOTODETECTORS. EACH PAGE OF THE MEMORY IS A HOLOGRAM. TO FORM EACH HOLOGRAM, A BEAM OF LIGHT IS DIRECTED THROUGH A CONVERGING LENS AND A PAGE OF DIGITAL DATA TO A PORTION OF A RECORDING MEDIUM LOCATED AT THE FOCAL POINT OF THE LENS. THERE THE CONVERGING BEAM OF LIGHT INTERFERENCES WITH A REFERENCE BEAM. AN APERTURE IN A MASK OVER THE RECORDING MEDIUM DEFINES THE PORTION OF THE RECORDING MEDIUM WHERE THE HOLOGRAM IS RECORDED. FOR EACH SUBSEQUENT HOLOGRAM THAT IS RECORDED. THE CONVERGING LENS AND THE MASK ARE FIRST MOVED AN EQUAL AMOUNT IN THE SAME DIRECTION PARALLEL TO THE SURFACE OF THE RECORDING MEDIUM AND THE ABOVE-DESCRIBED HOLOGRAM FORMING PROCEDURE IS REPEATED. AS A RESULT OF THIS RECORDING PROCESS, THE REAL IMAGE FROM EACH HOLOGRAM STORED IN THE MEMORY CAN BE RECONSTRUCTED AT THE SAME LOCATION AND THEREFORE READ BY ONE ARRAY AO PHOTODETECTORS. TO DISTRIBUTE THE LIGHT AMPLITUDE ON THE RECORDING MEDIUM MORE EVENLY THAN IT IS IN THE FOURIER TRANSFORM PLANE, EITHER THE LIGHT BEAM INCIDENT ON THE COVERGING LENS IS MADE SLIGHTLY DEVERGING OR CONVERGING OR FLY''S EYE LENS INSERTED INTO ITS PATH.

Inventors

• 👤 John Thomas La Macchia

Bibliographic Details