Polychromatic Wave-Optics Models for Image-Plane Speckle 2 Unresolved Objects
Polychromatic laser light can reduce speckle noise in many wavefront-sensing and imaging applications. To help quantify the achievable reduction in speckle noise, this study investigates the accuracy of three polychromatic wave-optics models under the specific conditions of an unresolved object. Because existing theory assumes a well-resolved object, laboratory experiments are used to evaluate model accuracy. The three models use Monte-Carlo averaging, depth slicing, and spectral slicing, respectively, to simulate the laser–object interaction. The experiments involve spoiling the temporal coherence of laser light via a fiber-based, electro-optic modulator. After the light scatters off of the rough object, speckle statistics are measured. The Monte-Carlo method is found to be highly inaccurate, while depth-slicing error peaks at 7.8% but is generally much lower in comparison. The spectral-slicing method is the most accurate, always producing results within the error bounds of the experiment.
Abstract © OSA.
Noah R. Van Zandt, Mark F. Spencer, Michael J. Steinbock, Brian M. Anderson, Milo W. Hyde, and Steven T. Fiorino, "Polychromatic wave-optics models for image-plane speckle. 2. Unresolved objects," Appl. Opt. 57, 4103-4110 (2018). doi:10.1364/AO.57.004103