Abstract

For multioutput logic systems, the polarization-encoded optical shadow-casting (POSC) algorithm¹ requires switching the source pattern² or switching of the decoding mask for a fixed input pattern. Recently, Rizvi et al.^2,3 proposed an extension of this algorithm to avoid this limitation. A careful observation of this algorithm² reveals that it may not always lead to a minimized design. However, a minimized design is often essential for logic circuits having large number of inputs and outputs, which is particularly important for POSC based logic circuits since the size of the input overlap pattern, source LED pattern, and the output overlap pattern are entirely dependent on the number of minterms and their proper spatial allocation. To achieve this objective, we propose an extremely efficient design algorithm that yields a minimized design and, at the same time, avoids the problems encountered with the algorithm of Refs. 1 and 2. To illustrate, we design an 8-to-3 line encoder using the proposed algorithm and compare it with that designed using the algorithm presented in Ref. 2. The proposed design is more efficient in terms of both the number of LEDs and spatial encoding size. Since the proposed algorithm requires less space for encoding the inputs, it is cost-effective as well as suitable for logic circuits having a large number of inputs and outputs.

© 1991 Optical Society of America