Reduction of false correlations with binary phase-only filters

Binary phase-only filters have considerable potential for use in optical correlation systems. However, simple correlation systems using these filters can give false correlation peaks and suffer from inherent noise. We describe a method by which these problems can be overcome by combining the results of sine and cosine binary phase-only correlations and demonstrate it by numerical simulation. Some problems of realizing the method in practice are also discussed.The authors are with Mechanical Engineering Laboratory, Namiki 1-2, Tsukuba-shi, Ibaraki 305, Japan.