Laser Lab A

Laser Lab A :

Instruments : He-Ne laser (15 mW Spectra-Physics), Photodiod, Storage digital

oscloscope (Tektronix 300 MHz, model TDS3032B), Optical

elements, Computer,…


Personal : H. Khoshsima, H. Tajalli, A. Ghanadzadeh

Project Title : Electro-optical characterization of some novel nematics

Abstract :
Liquid crystals (LC) are highly birefringent and non-linear optical materials due to their large molecular anisotropy and intermolecular ordering. Liquid crystal materials are unique in their properties and uses. Since most technical applications of nematic liquid crystals are based on their optical and electro-optical properties, the precise electro-optical data of new liquid crystalline materials are important and required. The wide range of electro-optical phenomena manifested by liquid crystals has inspired many investigations on these materials.
The values of the optical anisotropy can be obtained by electro-optical Kerr effect measurements, which depend both on polarity and polarizability of the molecules. The
electro-optical behavior is strongly related both to the chemical structure of a molecule
and to intermolecular interactions. The electro-optical effect may also be used to study pre-transitional behavior of liquid crystals in the isotropic phase.

Results :
Temperature dependence of B for (LC-I) and (LC-II) obtained using the a.c. field method (ƒ = 1kHz).
Temperature dependence of B-1 for (LC-I) and (LC-II) obtained using the a.c. field method.

Publications :

1- "Static Electro-optic kerr effect in a novel nematic liquid crystal".
(Proceeding of 11th Iranian Annual Conference on Optics & Photonics )
2- Electric birefringence of some nematic liquid crystals having a hexyl tail.
Proc. of SPIE Vol. 5947 59470P-1
Liquid Crystals: Optics and Applications, edited by Tomasz R. Wolinski, Marc
Warenghem, Shin-Tson Wu, Proc. of SPIE Vol. 5947, 59470P, (2005)
3-" Kerr effect investigations in liquid crystals contatinig the isothiocyanato and cyano groups with identical flexible tails " Mol. Cryst. Liq. Cryst . Vol. 460, pp.93-106 2006