Development Of An Optical Parallel Logic Device And A Half-Adder Circuit For Digital Optical Processing

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Abstract
An Optical Parallel Logic (OPAL) device which performs Boolean algebraic operations on two binary images has been developed. This device consists of a photoconductor and an electro-optic light modulating material appropriately arranged to bring about an in-teraction between the input signals. Two such OPAL devices have been interconnected to form a half-adder circuit (one of the essential components in the CPU of a futuristic digital optical processor). Operation of an 8 x 8 OPAL device containing CdS (photoconductor) and twisted nematic liquid crystal (electro-optic light modulating material) is reported. A contrast ratio of 20:1 was obtained. A circuit composed of two such devices is shown to perform addition of two 8 x 8 binary images generating SUM and CARRY images.