Holograms synthesized by computer are used for constructing optical wavefronts from numerically specified objects. Elimination of the need for a physical object has made new applications possible, for example, three-dimensional computer output displays, synthetic prototypes for interferometric testing, and filters for various optical data processing operations. Our computer holograms differ from a normal hologram in that the transmittance is binary, yet they are able to construct general

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... nts and images efficiently and have several practical advantages over holograms with a continuous range of transmittance. Recent improvements that simplify the production of binary holograms and improve their performance are described and experimental work showing reconstruction of two-and three-dimensional images is presented. B. R. Brown is located at the * This paper was presented at a symposium on holography at the University minor revisions from Symposium on the Engineering Uses of Holography, of Strathclyde, Glasgow, Scotland in September 1968 and is reprinted with Hologram synthesis by computer The process of synthesizing a hologram generally consists of four steps. First the propagation of the complex amplitude from the object to the hologram plane is computed. Actually, because of computer limitations, it is possible to compute the amplitude only at a finite number of IBM J. RES. DEVELOP.