Speckle decorrelation effects on motion-compensated, multi-wavelength 3D digital holography: theory and simulations

Abstract

.Digital holography enables 3D imagery after processing frequency-diverse stacks of 2D coherent images obtained from a chirped-frequency illuminator. To compensate for object motion or vibration, which is a common occurrence for long-range imaging, a constant temporal frequency or “pilot-tone” illuminator can act as a reference for each chirped frequency. We examine speckle decorrelation between the chirped and pilot-tone illuminators and its effect on the resultant range images. We show that speckle decorrelation between the two illuminators is more severe for facets of the object’s surface that are more highly sloped, relative to the optical axis, and that this decorrelation results in noise in the range images in the areas of the object that are highly sloped. We develop a theoretical framework along with wave-optics simulations for 3D imaging with a pilot tone, and we examine the severity of this noise as a function of several imaging parameters, including the illumination bandwidth, pulse frequency spacing, and atmospheric turbulence strength; we show that 3D sharpness metric maximization can mitigate some of the noise induced by turbulence, all in a simulated framework.