Paper
6 October 2005 Polarisation sensitive liquid crystal filter for polarization difference imaging
Andrzej Walczak, Edward Nowinowski-Kruszelnicki
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Abstract
The liquid crystal (lc) filter, which produces distributed form of light transmission, has been described. Distribution of the transmitted intensity may be altered in filter window by means of an incident light polarization. To obtain such polarization sensitive transmission the special alignment of a liquid crystal layer is arranged in such a way, that on the one side, inside the filter, the lc layer has been aligned as planar or homeotropic, while on the opposite side of the filter it stay aligned in form of circles. Such liquid crystal cell may be called circular - homogeneous or circular homeotropic (CH LC). The filter transmission basis is adiabatic following in a twisted nematic lc layer (Mauguin regime). As Mauguin regime is fulfilled then CH alignment causes polarization sensitive transmission. Such filter provides new possibilities in a polarisation difference image analysis so may be convenient tool for a polarimetric image processing. Numerical simulation of the transmission has been presented as well as the experimental results. Even if Maugin regime is fulfil the examined filter transmission depends on the transmitted spectrum to some extent. It has been analyzed and potential application of this property of the filter has been discussed too.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Andrzej Walczak and Edward Nowinowski-Kruszelnicki "Polarisation sensitive liquid crystal filter for polarization difference imaging", Proc. SPIE 5947, Liquid Crystals: Optics and Applications, 594708 (6 October 2005); https://doi.org/10.1117/12.622801
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KEYWORDS
Liquid crystals

Polarization

Image filtering

Optical filters

Birefringence

Polarizers

Image processing

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