The theory of coherent image detection

The paper is concerned with the problem of the coherent detection of laser emission reflected from a rough surface. Formulas are obtained which relate the sensitivity of the photosensitive detection device to the lens diameter. It is shown that first the signal strength increases with the lens diameter, but later saturation occurs when the coherence zone of the received signal in the image plane becomes smaller than the size of an individual element of the photosensitive array.