Speckle formation through an optically thick diffuser: A wave propagation-based model

Abstract

Speckle effect arises from coherent light interacting with rough surfaces or randomly scattered media, offering useful parameters for metrology. Inspired by the phase-screen method used to simulate atmospheric turbulence effects on optical systems, this study investigates speckle generated from a numerical model that simulates wave propagation through multiple apertured phase screens imposed with diffuse illumination as a thick diffuser. It is observed that as the number of phase screens increases, the diffraction intensity increases as well, yet its width scan eventually gets narrower until it matches the dimensions of the aperture. Additionally, when the wave propagates through a single phase screen, the speckle size is relatively larger compared to the propagation involving multiple screens. Speckle size is quantified by obtaining the full width at half maximum (FWHM) of the autocorrelation profiles of the speckle frames.