SPECKLE

Speckle reduction in laser projections with ultrasonic waves

[+] Author Affiliations
Lingli Wang

Philips Center for Manufacturing Technology, PO Box 218/SAQ-p, 5600?MD Eindhoven, The Netherlands

Theo Tschudi, Markus Boeddinghaus, Alexander Elbert

Institute of Applied Physics, Darmstadt University of Technology, Hochschulstr. 6, D-64289?Darmstadt, Germany

Thorsteinn Halldo´rsson

DaimlerChrysler AG, Research and Technology, FT2/ES, Postfach 800465, D-81663?Munich, Germany

Pa´lmi Pe´tursson

Riesbogen 14, D-85635?Ho¨henkirchen, Germany

Opt. Eng. 39(6), 1659-1664 (Jun 01, 2000). doi:10.1117/1.602543
History: Received July 29, 1999; Revised Nov. 29, 1999; Accepted Dec. 9, 1999
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Abstract

In laser front projection display, the observer in the far field of the image pixels on the screen will observe serious speckle noise. For the first time we show a way to eliminate speckles in the far field by modulating a laser beam with traveling ultrasonic waves in a liquid cell. The resulting running interference fringes in a pixel on the screen will produce a boiling speckle pattern, which will be time-averaged in the eye of the observer. By superposition of ultrasonic waves of different frequencies, the speckle contrast can be reduced even further. We optimized the modulation frequencies, as well as the scattering properties of different screen materials. The intensity modulation depth of the speckle pattern could be reduced to a few percent without noticeable influence on the beam quality. © 2000 Society of Photo-Optical Instrumentation Engineers.

© 2000 Society of Photo-Optical Instrumentation Engineers

Citation

Lingli Wang ; Theo Tschudi ; Markus Boeddinghaus ; Alexander Elbert ; Thorsteinn Halldo´rsson, et al.
"Speckle reduction in laser projections with ultrasonic waves", Opt. Eng. 39(6), 1659-1664 (Jun 01, 2000). ; http://dx.doi.org/10.1117/1.602543


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