Reduction of image speckle noise with the use of an integrative synthetic aperture imaging technique is studied. It is found that the Fourier inversion of the mutual intensity estimate [Appl. Opt. 30, 206–213 (1991)] yields an image intensity that corresponds exactly to the illumination of the object with partially coherent light from source optics imaging a delta-function incoherent source. An expression for the signal-to-noise ratio at an image point is derived for a large rough object with delta-function correlated amplitude reflection. A synthetic aperture system receiver of sufficiently small diameter yields image speckle with a signal-to-noise ratio (SNR) equal to 1. When the receiver and the transmitter diameters are equal, the SNR is 2 for linearly polarized speckle. The SNR continues to increase with receiver size and is linear in the diameter for large receiver-to-transmitter diameter ratios.
© 1992 Optical Society of America
Louis Sica, "Image speckle contrast reduction resulting from integrative synthetic aperture imaging," Appl. Opt. 31, 120-125 (1992)