Speckle Reduction in Imaging Projection Systems


Diffractive diffusers (phase gratings) are routinely used for homogenizing and beam shaping for laser beam applications. Another use for diffractive diffusers is in the reduction of speckle for pico-projection systems. While diffusers are unable to completely eliminate speckle they can be utilized to decrease the resultant contrast to provide a more visually acceptable image. Research has been conducted to quantify and measure the diffusers overall ability in speckle reduction. A theoretical Fourier optics model is used to provide the diffuser’s stationary and in-motion performance in terms of the resultant contrast level. Contrast measurements of two diffractive diffusers are calculated theoretically and compared with experimental results. Having a working theoretical model to accurately predict the performance of the diffractive diffuser allows for the verification of new diffuser designs specifically for pico-projection system applications.

Share and Cite:

W. Thomas and C. Middlebrook, "Speckle Reduction in Imaging Projection Systems," Optics and Photonics Journal, Vol. 2 No. 4, 2012, pp. 338-343. doi: 10.4236/opj.2012.24042.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] J. W. Goodman, “Speckle Phenomena in Optics: Theory and Applications,” Roberts & Company, Englewood, 2007, p. 387.
[2] J. I. Trisnadi, “Hadamard Speckle Contrast Reduction,” Optics Letters, Vol. 29, No. 1, 2004, pp. 11-13. doi:10.1364/OL.29.000011
[3] W. Thomas, C. Middlebrook and J. Smith, “Laser Speckle Contrast Reduction Measurement Using Diffractive Diffusers,” Proceedings of SPIE, Emerging Liquid Crystal Technological IV, Vol. 7232, 2009, 11 p.
[4] D. D. Duncan, S. J. Kirkpatrick and R. K. Wang, “Statistics of Local Speckle Contrast,” Journal of the Optical Society of America, Vol. 25, No. 1, 2008, pp. 9-15. doi:10.1364/JOSAA.25.000009
[5] C. N. Kurtz, H. O. Hoadley and J. J. Depalma, “Design and Synthesis of Random Phase Diffuser,” Journal of the Optical Society of America, Vol. 63, No. 9, 1973, pp. 10801092. doi:10.1364/JOSA.63.001080
[6] C. N. Kurtz, “Transmittance Characteristics of Surface Diffusers and the Design of Nearly Band-Limited Binary Diffusers,” Journal of the Optical Society of America, Vol. 62, No. 8, 1972, pp. 982-989. doi:10.1364/JOSA.62.000982
[7] J. W. Goodman, “Statistical Optics,” Wiley Classics Library, John Wiley & Sons, Hoboken, 2000, p. 550.
[8] Y. Nakayama and M. Kato, “Diffuser with Pseudorandom Phase Sequence,” Journal of the Optical Society of America, Vol. 69, No. 10, 1979, pp. 1367-1372. doi:10.1364/JOSA.69.001367
[9] D. Voelz, “Computational Fourier Optics: A MATLAB Tutorial,” SPIE Tutorial Texts, SPIE Press, Bellingham, 2011, p. 250.
[10] D. A. Gremaux, “Limits of Scalar Diffraction Theory for Conducting Gratings,” Applied Optics, Vol. 32, No. 11, 1993, pp. 1948-1953. doi:10.1364/AO.32.001948
[11] J. E. Harvey, “Fourier Treatment of Near-Field Diffraction Theory,” American Journal of Physics, Vol. 47, No. 11, 1979, pp. 974-980. doi:10.1119/1.11600
[12] J. T. Verdeyen, “Laser Electronics,” In: J. Nick Holonyak, Ed., Prentice Hall Series in Solid State Physical Electronics, 3rd Edition, Prentice Hall, Saddle River, 2000, p. 778.
[13] H. Loui, “Fourier Propagation, in Numerical Methods in Photonics Project 2004,” University of Colorado, Boulder, pp. 1-5.
[14] J. W. Goodman, “Introduction to Fourier Optics,” 3rd Edition, Roberts & Company, Englewood, 2005.
[15] M. Livingstone, “Vision & Art: The Biology of Seeing,” Harry N. Abrams, New York, 2002.
[16] J. W. Tom, A. Ponticorvo and A. K. Dunn, “Efficient Processing of Laser Speckle Contrast Images,” IEEE Transactions on Medical Imaging, Vol. 27, No. 12, 2008, pp. 1728-1738. doi:10.1109/TMI.2008.925081

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.