Laser speckle poses an ongoing challenge to optical systems that utilize coherent light for active illumination, including applications in holography, free-space communications, remote sensing and target tracking. Speckle averaging offers one potential path forward by reducing the contrast, thereby boosting signal-to-noise ratios. This approach becomes limited, however, by the degree of correlation between successive frames. Wave-optics simulations help to characterize performance gains through speckle averaging, and so it is important that existing models properly account for decorrelation rates of dynamic speckle. With that goal in mind, this research seeks to build a suite of computational wave-optics experiments that verify speckle correlation statistics in the pupil and image planes of a black-box system. For an extended target surface that is rough compared to the wavelength of illumination, decorrelation arises from four different modes of simulated target motion; namely, in-plane and out-of-plane translation and rotation. Furthermore, test cases include uniform scattering spots and fundamental Gaussian beams, along with hard and soft apertures of different shapes. Relative to closed-form expressions for the correlation coefficient of irradiance, results demonstrate that the speckle is properly correlated from one frame to the next. This outcome bolsters simulation capabilities wherever speckle averaging is concerned, with the best-case scenario being total decorrelation at each time step. Studies of this kind are critical in the design process of coherent optical systems.
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Master of Science (M.S.)
College of Optics and Photonics
Optics and Photonics
Optics and Photonics
Length of Campus-only Access
Masters Thesis (Open Access)
Burrell, Derek, "Wave-optics Simulation of Correlated Speckle Fields" (2020). Electronic Theses and Dissertations, 2020-. 433.