Real-time pattern recognition by means of incoherent optical space frequency analysis

It is known that a transition from object to spatial-frequency domain with the aid of the Fourier transform may be a suitable solution for the problem of real-time pattern recognition of objects whose features cannot be determined exactly. The paper discusses the method of incoherent space frequency analysis with the aid of liquid-crystal light modulators. The hardware based on this technique can be simple and economical, and it overcomes a number of disadvantages of coherent-optical set-up. The parameters of LC modulators are discussed. These may be used to derive operational conditions, processing spreads, etc. of the optical processors involved. Selected examples illustrate suitable applications.