SPECKLE NOISE IN LASER BAR-CODE-SCANNER SYSTEMS

We present a theoretical model and its experimental verification for s peckle-induced noise in laser-based bar-code-scanner systems. We measu red the dependence of the signal-to-speckle-noise ratio on distance, s pot size, and detector size. Analyses of the power spectra of both the speckle noise and of the measured surface profiles of different subst rates suggest that the paper surface granularity can be approximated b y a white Gaussian noise process, thus confirming the assumption of th e theoretical model. (C) 1996 Optical Society of America