Abstract

In this paper a general method is presented for calculating the theoretical speckle contrast of a sum of correlated speckle patterns, motivated by the need to suppress the presence of speckle in laser projection displays. The method is applied to a specific example, where correlated speckle patterns are created by sequentially passing light through partially overlapping areas on a diffuser, before being projected onto a screen. This design makes it possible to find a simple expression for the correlation between speckle patterns. When the set of correlations involves symmetry, it is shown that the expression for the speckle contrast becomes simpler. The difference in performance between discretely and continuously varying speckle patterns is also investigated. In an example with speckle reduction by a rotating sinusoidal grating, it is found that continuous variation gives a speckle contrast that is 0.61 times the contrast obtained by discretely summing the maximum number of independent patterns.

©2012 Optical Society of America

Speckle contrast for superposed speckle patterns created by rotating the orientation of laser polarization

Zhaomin Tong and Xuyuan Chen
J. Opt. Soc. Am. A 29(10) 2074-2079 (2012)

Two-point joint probability-density function for the intensities of the sum of partially developed speckle patterns

V. S. Rao Gudimetla
J. Opt. Soc. Am. A 9(7) 1119-1123 (1992)

Spectral correlation of partially or fully developed speckle patterns generated by rough surfaces

Bernd Ruffing and Jürgen Fleischer
J. Opt. Soc. Am. A 2(10) 1637-1643 (1985)

Speckle suppression in projection displays by using a motionless changing diffuser

Vladimir Kartashov and Muhammad Nadeem Akram
J. Opt. Soc. Am. A 27(12) 2593-2601 (2010)

Surface-roughness dependence of the intensity correlation function under speckle-pattern illumination

Takeaki Yoshimura, Kazuo Kato, and Kiyoshi Nakagawa
J. Opt. Soc. Am. A 7(12) 2254-2259 (1990)