Contrast Reversal of a Binary Periodic Object

The optical properties of periodic objects are used to obtain contrast reversal, i.e. the negative is obtained in a simple optical arrangement, in real-time, without chemical processing. Two methods of contrast reversal are presented. Method I makes use of the self-imaging phenomenon and Method II, the discrete form of the Fourier spectrum of periodic signals. Experimental results are included, illustrating the effectiveness of the methods.