On the basis of a lensless shadow-casting technique, a new, simple method of optically implementing digital logic gates has been developed. These gates are capable of performing a complete set of logical operations on a large array of binary variables in parallel, i.e., the pattern logics. A light-emitting diode (LED) array is used as an incoherent light source in the lensless shadow-casting system. Sixteen possible functions of two binary variables are simply realizable with these gates in parallel by controlling the switching modes of the LED’s. Experimental results demonstrate the feasibility of various gate arrays, such as AND, OR, NOR, XOR, and NAND. As an example of application of the proposed method, we construct an optical logic array processor that can implement parallel operations of addition or subtraction for two binary variables without considering the carry mechanism. Use of the light-modulated LED array means that the proposed method can be applied to combinational circuits.
© 1983 Optical Society of AmericaPDF Article