ABSTRACT
Speckle is a random interference pattern resulting from the coherent addition of light waves from different points. Electro-optical engineers most often encounter speckle in laser-illuminated objects viewed through an imager. However, a random interference pattern can occur for any electromagnetic radiation with sufficient coherence by combining several phase-shifted versions of itself. Even the coherence of starlight can yield stellar speckle. Radar also exhibits the phenomenon, particularly from surfaces such as ocean waves. Cellular telephony suffers fading from multipath signals, a phenomenon analogous to speckle. The sections that follow treat laser speckle in the visible and infrared portions of the spectrum. Speckle in imagers is emphasized along with simulations of speckle phenomena.
