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The variation in the ac output current in a coherent optical‐detection process as a function of orientation has previously been analyzed for point sources. The work is extended here to include finite sources, finite bandwidth, random‐phase sources, and rough surfaces. The general expression for two finite sources in the Fraunhofer region indicates that the directivity is the product of the radiation patterns of the individual sources multiplied by the directivity of the detector due to point sources. For typical lasers the bandwidths are so narrow that the directivity is not practically affected by the finite width. ``White'' surfaces are shown to be equivalent to uniform surfaces with a random phase which is statistically independent from point to point. These surfaces are shown to have effectively the same directivity as far‐field point sources.