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1

Influence of chirality on two-dimensional deformations in twisted flexoelectric nematic layers

Buczkowska Mariola

Scientific Bulletin. Physics / Lodz University of Technology

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2019

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Vol. 40

5--12

EN

Two-dimensional deformations induced by electric field in twisted nematic cells filled with liquid crystal possessing flexoelectric properties were simulated numerically. The influence of chiral dopants on the occurrence and structure of the spatially periodic patterns was investigated. It was found that the chirality influences mainly the direction of the periodic patterns whereas the threshold voltage for deformation and the width of the stripes are weakly affected

PL

Dwuwymiarowe deformacje indukowane polem elektrycznym w warstwach ciekłych kryształów nematycznych posiadających właściwości fleksoelektryczne były symulowane numerycznie. Zbadano wpływ chiralnych domieszek na strukturę tych odkształceń i ich rozwój pod wpływem pola elektrycznego. Stwierdzono, że chiralność wpływa głównie na kierunek odkształceń, podczas gdy napięcie progowe na odkształcenie i przestrzenny okres odkształceń słabo zależą od chiralności nematyka. Stwierdzono, że chiralność wpływa głównie na kierunek odkształceń, podczas gdy jej wpływ na napięcie progowe i na przestrzenny okres odkształceń jest nieznaczny.

2

Two-dimensional deformations in twisted flexoelectric nematic cells

Derfel G., Buczkowska M.

Scientific Bulletin. Physics / Lodz University of Technology

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2016

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Vol. 37

21--30

EN

Electric field induced deformations occurring in twisted nematic cells filled with liquid crystalline material possessing flexoelectric properties were simulated numerically. The aim of computations was to compare the two-dimensional periodic deformations with one-dimensional distortions reported in our earlier paper occurring in the same cells. It was found that the periodically deformed structures have lower free energy counted per unit area of the layer than the one-dimensional deformations.

PL

Przeprowadzono symulacje wywołanych polem elektrycznym odkształceń występujących w skręconych warstwach nematyków posiadających właściwości fleksoelektryczne. Ich celem było porównanie deformacji dwuwymiarowych z deformacjami jednowymiarowymi tych samych warstw, opisanymi we wcześniejszym artykule. Stwierdzono, że struktury przestrzennie okresowe mają niższą energię niż deformacje jednowymiarowe.

3

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

Piecek W., Jaroszewicz L. R., Miszczyk E., Raszewski Z., Mrukiewicz M., Perkowski P., Nowinowski-Kruszelnicki E., Zieliński J., Olifierczuk M., Kędzierski J., Sun X. W., Garbat K., Kowiorski K., Morawiak P., Mazur R., Tkaczyk J.

Opto-Electronics Review

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2016

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Vol. 24, No. 4

169--182

EN

There exists a need in a quality and accuracy of a three-dimensional laser metrology operating in numerically controlled automatic machines. For this purpose, one sends three laser beams mutually perpendicular. These three beams of the wavelength λ = 0.6328 μm are generated by the same laser and are directed along three independent, orthogonal, mutually perpendicular, optical paths with a given light polarization plain. Using these beams, constituting the frame of coordinates, three independent laser rangefinders are able to determine spatial coordinates of a working tool or a work piece. To form these optical pulses, a special refractive index matched Half-Wave Plate with nematic Liquid Crystal (LCHWP) was applied. The presented half-wave plate is based on a single Twisted Nematic (TN) cell (with the twist angle φ = π/2) of a rather high cell gap d ~15 μm filled with a newly developed High-Birefringence Nematic Liquid Crystal Mixture (HBLCM) of optical anisotropy as high as ∆n ~0.40 at λ = 0.6328 μm, where the Mauguin limit above 5.00 ~ ∆nd >> λ/2 = 0.32 is fulfilled.

4

Liquid crystal cell for space-borne laser rangefinder to space mission applications

Nowinowski-Kruszelnicki E., Jaroszewicz L., Raszewski Z., Soms L., Piecek W., Perkowski P., Kędzierski J., Dąbrowski R., Olifierczuk M., Garbat K., Miszczyk E.

Opto-Electronics Review

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2012

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Vol. 20, No. 4

315-322

EN

Liquid crystal cell (LCC) for space-borne laser rangefinder to space mission applications was developed, manufactured and tested under cooperation between Military University of Technology (MUT) in Poland and Vavilov State Optical Institute (Vavilov SOI) in Russia. LCC operates in twisted nematic mode, commutating the polarization plane of a laser beam working at 1.064 µm and the energy density not smaller than 0,15 J/cm² at the pulse duration about 8 ns. The transmission of LCC is not smaller than 95% at the aperture diameter not less than 15 mm. Switching on and switching off times in a 2.5-µm thick LCC driven by voltage of 10 V are not larger than 0.7 ms and 7 ms, respectively, in the operating temperature range from 20°C to 40°C. The LCCs developed in MUT were positively tested under space requirements in Vavilov SOI.

5

Significante of reflection reduction in a TN display for colour visualisation

Olifierczuk M., Zieliński J.

Opto-Electronics Review

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2002

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Vol. 10, No. 1

35-37

EN

This paper contains the results of theoretical considerations about light propagation through the real TN display working in reflective and negative mode. This mode provides us with a possibility to obtain a colour image. We have done mathematical and numerical analyses of a propagation of light wave through liquid crystal (LC) displays with antireflective layer, glass planes, conductive layers, LC layer and polarisers. We have taken into account real conditions of a display operation, i. e., spectral properties of all components, optical anisotropic and dichroic properties of LC layer, reflections from all phase borders and also spectral characteristics of light source and sensitivity of human eye.