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In this paper we describe an acousto-optic morphological image processor used to implement a morphological hit-or-miss transform. Morphology is an image algebra technique whereby the shape and structure of an input object is transformed by a smaller object referred to as a structuring element. The two most fundamental morphological operations, erosion and dilation, can be implemented as a convolution followed by a threshold. We perform the convolution optically and the threshold digitally. The input to the system is displayed on an Epson 1020 LCTV, and the system utilizes an acousto-optic Bragg cell in the Fourier plane of a coherent optical correlator to generate the desired structuring element. The hit-or-miss transform is the intersection of two eroded images. One image is the input object eroded by the desired structuring element, and the second image is the erosion of the complement of the input by the complement of the structuring element. This transform is useful for extracting specified features from images, as is necessary in automatic target recognition. Experimental results are presented.

The development of free-space optical interconnect systems has created a need for efficient algorithms for the design of multiple beam splitting optical elements commonly referred to as array generators. A technique for the design of continuous phase gratings is presented that is based on the representation of the array generator in terms of complex poles and zeroes. Infinite impulse response filter design theory is then applied to array generator design; an all-pass IIR filter insures that the phase-only constraint is always satisfied. A stochastic optimization algorithm is presented that is based on the specification of complex poles and zeroes. Preliminary results indicate the efficacy of using IIR filter design techniques, but grating performance to date is only moderate. Phase gratings have been designed that generate spot arrays at ~90% diffraction efficiency with 7% uniformity.

Morphology is an image algebra technique whereby the shape and structure of an input object is transformed by a smaller object called the structuring element. The two most fundamental morphological operations, erosion and dilation, are usually defined in terms of set operations. Alternatively they can be understood in terms of a convolution followed by a threshold. In this paper we describe an iterative acoustooptic (AO) morphological image processor. The input to the system is displayed on a 128 × 128 magnetooptic spatial light modulator, and the system utilizes an AO Bragg cell in the Fourier plane of a coherent optical correlator to generate the desired structuring element. Thresholding is performed electronically in an image processing system. The feedback necessary for multiple erosions and dilations is provided electronically via a single computer that controls both an image processing system in the output image plane and the MOSLM.