[OPTICAL REVIEW Vol. 21, No. 1 (2014) 83-89]
© 2014 The Japan Society of Applied Physics

Color Speckle

Kazuo KURODA1*, Tomoharu ISHIKAWA1, Miyoshi AYAMA1, and Shigeo KUBOTA2

1Center for Optical Research and Education, Utsunomiya University, Utsunomiya 321-8585, Japan
2Oxide Corporation, Yokohama Branch, Yokohama 223-8551, Japan

(Received June 27, 2013; Accepted October 1, 2013)

Speckle is a random distribution of a radiant power density or an irradiance on the observation plane (retina of observers in the laser display) due to the interference of randomly phase-modulated wavefronts. Since a color is synthesized by the superposition of red-green-blue (RGB) primary-color lasers in laser displays, if the speckle patterns of RGB lasers are uncorrelated with each other, then the fluctuation in radiant power density results in a change in color received by the observer. We name this random distribution of color “color speckle”. The distribution of color on the xy chromaticity diagram is investigated for speckle patterns of various speckle contrasts. We demonstrate a numerical simulation of color speckle. Then, we derive the theoretical expressions of the variance and covariance of the distribution of xy chromaticity under the assumption of low speckle contrast.

Key words: laser display, speckle, color

*E-mail address: kuroda@opt.utsunomiya-u.ac.jp