High Birefringence Liquid Crystals Mixtures and their Selected Applications

Abstract

High-Birefringence Nematic Liquid Crystals Mixtures (HBNLCM) recently developed in the Military University of Technology (Poland) are presented in this paper. Dielectric, refractometric, viscosimetric and elastomeric characteristic were determined. The properties are discussed in terms of their applicability to electro-optical devices. Applying HBNLCM of LCM to space mission (Phobos Ground) applications for a space-borne laser rangefinder was developed, manufactured and tested under cooperation between Military University of Technology (MUT) in Poland and Vavilov State Optical Institute (Vavilov SOI) in Russia. Transmission T of Liquid Crystal Cell (LCC) at λ=1.064 μm was not smaller than 95% at the aperture diameter not less than 15 mm. Switching on and switching off times in 2.5 μm thick LCC driven by voltage 10 V were not larger than 0.7 ms. Applying HBNLCM of LCM3 to refractive index matched twisted Nematic Liquid Crystal Cell of type LCNP4 for Thomson diagnostics of dense plasma was developed, manufactured and tested under cooperation between MUT in Poland and the National Research University of Information Technologies, Mechanics and Optics in Russia. Transmission T of LCNP4 at λ=1.064 μm was not smaller than 97% at the aperture diameter not less than 30 mm. Switching on time in 2.5 μm thick LCNP4 driven by voltage 200 V was not larger than 3 μs. LCNP4 can easily tolerate 0.42 J/cm2.

Refractive index matched half-wave plate with a nematic liquid crystal for three-dimensional laser metrology applications

“…If the LCHWP mentioned above, at 60°C has got the product d × Dn higher than 5, decreasing temperature below 60°C should increase d × Dn and the requirements as for: T max > 0.95, Q~90.0°and dQ = Q u -90.0°= ±1.5°should be satisfied. The above conclusion was verified by data pre− sented below, obtained from our experiments with HBLCM described at point 3 and temperature investigation on LCHWP described at point 4: [13][14][15]. By combining several compo− nents, one can control the properties of resulting liquid crys− talline mixtures, such as birefringence, viscosity, refractive indices, dielectric permittivities and elastic constants in ac− cordance with requirements for selected applications.…”

Transparent laser damage resistant nematic liquid crystal cell “LCNP3”

“…LCMs [8][9][10] developed at the MUT, containing isothiocya− nato tolane and isothiocyanato terphenyl liquid crystals, are distinguished by relatively high optical anisotropies. LCM (described in [2,4]) among the others consisted of fluoro− substituted alkyltolane and alkylphenyltolane isothiocyana− tes. A subsequent working mixture LCM3 in general com− prised nearly the same components as LCM does.…”

“…The sheet resistance of porous ITO (P−ITO) layers was r~1800 W/c and the refractive index was n~1.50 [2,10,20]. In order to electrically isolate a transparent P−ITO elec− trode from LCM3 (characterized by n o = 1.54 at l = 1.064 μm) a dielectric blocking film (BF) was evaporated on a P−ITO layer.…”

“…One knows that: LCCs operated in "positive TN mode" with rubbed Ny− lon (NL) 6/6 alignment layers and transparent Porous In− dium Tin Oxide (P−ITO) electrodes (with n~1.54 and sheet resistance r~1500 W/c) obtained by special depo− sition, Laser Damage Resistance is LDR~0.4 J/cm 2 for l = 1.064 μm in nanosecond range duration [2,3]. Taking the above into account the special refractive index matched twisted LCC was prepared by using of porous Indium Tin Oxide (P−ITO) and Nylon 6/6 polyamide (NL) orienting layers.…”

“…According to our experiences [1][2][3][4][5][6] the LCNP3 cell exhibiting both high transmission T > 97% and short swit− ching on time t ON < 3 μs was created by using a passive TN mode working at the first interference maximum. The LCNP3 cell with a clean aperture of 20 cm 2 was developed and manufactured under cooperation between Military Uni− versity of Technology (MUT), Poland and Vavilov State Optical Institute (VSOI), Russia.…”