The adoption of light emitting diodes by lighting industry is inevitable. They provide many advantages, but one of them is very interesting from the point of view of using liquid crystals: it is the small etendue of these sources. Rather well collimated and small diameter white light beams can be obtained. Here is where liquid crystal lenses can have an important application. We report the development of an optical element that can dynamically stretch broad band beams in one or in orthogonal or in both directions. Thus, we can start from a narrow circular beam and obtain a rectangular shaped beam to fit perfectly the size and the exposure requirements in home, office, architectural or automobile applications. The basics of its operation as well as of its optical performance data will be reported.
Recently, we have demonstrated a new approach to fabricate a variable focal lens using polymer-stabilized liquid crystals [1, 2]. The approach is based on curing of a polymer/liquid crystals mixture with a circularly symmetric (e.g. Gaussian) shaped laser beam to induce spatially inhomogeneous polymer network. Applying a uniform voltage to the non-pixilated cell leads to circular-symmetric (lens-like) distribution of refractive index in the cell with plane parallel substrates.
In this paper we study and optimize the electro-optical characteristics of such lens by varying the wavelength of the polymerizing laser, temperature regime of the process of polymerization as well as frequency of the lens driving voltage. Obtained results are applied to develop lenses that have no moving components and allow the electro-optical zooming.
REFERNCES
[1] V.V.Presnyakov, T.V.Galstian, K.E.Asatryan, A.Tork. "Polymer-Stabilized Liquid Crystal for Tunable Microlens Applications", Optics Express, 10, 17, 865-870, 2002.
[2] V.V.Presnyakov, T.V.Galstian. "Variable Focal Length Lens Based on Polymer-Stabilized Nematic Liquid Crystals", 19th International Liquid Crystal Conference, Edinburgh, UK, June 30 – July 5, 2002, Book of Abstracts, P754.
Nuclear pore membranes are polymer films with nano- or micro-metric size diameter pores, which are created through the film by irradiation with heavy ions and then chemical etching of the corresponding nuclear traces. The potential of creation of color filters with spectral characteristics controllable by an electric signal was recently demonstrated. To achieve this control it is necessary to obtain nuclear pore membranes with pores thar are oblique, rather than perpendicular to the polymer film. In this paper we present the methods of fabrication of such structures as well as the investigation of their morphological and spectral properties.
The IR-140 dye has a maximum of absorption in the near infrared spectral range. It can be used successfully for the initiation of photopolymerization in various organic complexes based on polymers and liquid crystals. In this paper we report the experimental observations of the strong influence of the nematic liquid crystal matrix on the spectral properties of this dye. The character of interaction between the dye and liquid crystalline host and its influence on the wavelength dependence of photopolymerization cross section are analyzed.
The transmission spectra of nuclear pore membranes filled with nematic liquid crystal have been measured depending upon the transversally applied voltage. It has been shown that spectral and electro-optical characteristics of membranes with ensemble of uniformly ordered oblique pores strongly depend on the direction of polarization of incident light. The transmission spectrum of the polarized light passed through such membrane has few maxima and minima with field-varied positions on the wavelength axis. Presented results can be used to develop polarizer-free tunable color filters.
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