Liquid Crystal Filter LCF
Pp. 96-113 (18)
Leszek R. Jaroszewicz,
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.
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.