The properties of the image of a nonuniform transparency degraded by speckle noise are studied. Attention is focused on the spatial details of an object that cannot be resolved by a coherent system. Analysis of the power spectrum of the noisy spatial-intensity distribution in the image plane confirms that the bandwidth for coherent diffuse illumination corresponds to the incoherent transfer function of the system. Experimental verification is presented using a Ronchi ruling as a test object.
© 1984 Optical Society of America
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