Generation of random arrays using clipped laser speckle.

A technique for generating 2-D arrays of random numbers using clipped laser speckle is presented. A 2-D detector array is exposed to a fully developed laser speckle pattern. When the output of the array is clipped, the elements with value above threshold are set to unity while the others are set to zero. The result is an array of randomly positioned elements of unit value. The spatial coordinates of the elements above threshold are taken as the random deviates. By controlling the clipping threshold for each element, one can dictate the probability that the clipped output from each element will be above threshold. Any distribution can be produced by varying the probability that the output from each element is above threshold. We present experiments performed on a 256 × 256-element detector array for which the elements were individually addressable. The integration time for each detector can be adjusted to obtain various distributions. Applications of random arrays include Monte Carlo calculations and coherent pattern recognition.