Control of Laser Speckle Noise Using Liquid Crystals

Control of Laser Speckle Noise Using Liquid Crystals

Laser speckle noise occurs owing to the strong interference that originates in the high coherency of laser light and the surface topography of the screen. The suppression of the speckle noise is necessary for laser displays such as in an image projection system. In order to reduce speckle noise, we...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics Vol. 50; no. 9; pp. 09NE14 - 09NE14-3
Main Authors: Furue, Hirokazu, Terashima, Atsuo, Shirao, Masato, Koizumi, Yukio, Ono, Masatoshi
Format: Journal Article
Language:English
Published: The Japan Society of Applied Physics 01-09-2011
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Summary:Laser speckle noise occurs owing to the strong interference that originates in the high coherency of laser light and the surface topography of the screen. The suppression of the speckle noise is necessary for laser displays such as in an image projection system. In order to reduce speckle noise, we try to control the speckle pattern by using liquid crystals that have electrically controllable optical characteristics. The modulation of polarized light using the birefringence of liquid crystals is very effective. However, the ratio of noise reduction does not exceed 30%. This is because the polarized light transmitted through the liquid crystal medium is formed by only two optical eigenmodes. The wedge-type liquid crystal cell can control the position of the laser spot on the screen. The incident-angle modulation of laser light is also effective for noise reduction.
Bibliography:Optical measuring system used in this research. Photographs of speckle patterns after introducing SSFLC with cell gap of 1.8 μm. Microscopic textures and electrooptical effect of PSFLC with cell gap of 1.6 μm. Photographs of speckle patterns: cell gap was 1.6 μm in both FLC cells. Photographs and histograms of speckle patterns: SSFLC was used and the cell gap was 1.8 μm.
ISSN:0021-4922
1347-4065
DOI:10.1143/JJAP.50.09NE14