Liquid Crystal Light Modulators: Revised Edition

Liquid Crystal Light Modulators: Revised Edition

This brief monograph provides reports on liquid crystal materials used for specific devices designed for industrial applications. The authors of each chapter present insights on the design and ...
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Liquid Crystal Filter LCF

Pp. 96-113 (18)

DOI: 10.2174/9789811470226120010009

Author(s): Leszek R. Jaroszewicz, Zbigniew Raszewski

Abstract

Multicomponent Nematic Liquid Crystalline mixtures (MNLC) containing isothiocyanato tolane and isothiocyanato terphenyl liquid crystals have been developed at the MUT. Some of them exhibit both; high optical (Δn ≤ 0,45) and high dielectric (Δε ≤ 20) anisotropies and are characterized by relatively low viscosity γ. Appling the mentioned above MNLC mixtures (W1791, See Chapter 2) in HG (HomoGeneously aligned) cells with thicknesses d about 1 μm, 3 μm and 5μm, one can obtain the possibilities to develop first-order electrically tunable liquid crystal filter and threestage ETLCF (Electrically Tunable Liquid Crystal Filter). Specific spectral filters can find some acceptance in astronomy and remote sensing for the pollution monitoring. Distinct advantages of ETLCF over conventional tunable filters are the possibility of construction of LCFs with an extremely large clear aperture, low power consumption, and low addressing voltage.

• Due to the relatively high and electrically controlled optical anisotropies Δn(U) of MNLC and by variation of cell gaps d (1 μm, 3 μm and 5 μm) used, the LCF can select the desired wavelength λ(U) from VIS and NIR ranges.

• Due to the high dielectric anisotropy Δε, low viscosity γ and small cell gap d of HG cells, the LCF can achieve the response time lower than 1 ms.

In this chapter, we describe our efforts in obtaining optimization of the LCFs.

Keywords:

Aperture, Dielectric anisotropy, Effective optical anisotropy, Homogeneous alignment, Liquid crystal cell, Liquid crystal filter, Nematic liquid crystalline mixture, Optical anisotropy, Ordinary refractive index, Rotational viscosity, Splay elastic constant, Switching on time.