Wyniki wyszukiwania - BazTech

1

Mid-wave infrared liquid crystal shutter for breathalyzer applications

Piecek W., Jaroszewicz L., Miszczyk E., Raszewski Z., Mrukiewicz M., Kula P., Jasek K., Perkowski P., Nowinowski-Kruszelnicki E., Zieliński J., Kędzierski J., Olifierczuk M., Chodorow U., Morawiak P., Mazur R., Kowiorski K., Harmata P., Herman J.

Opto-Electronics Review

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2017

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Vol. 25, No. 2

103--109

EN

There exists a problem with an in situ diagnostics of contamination of ethyl alcohol in a human being exhaled air. When ethyl alcohol in a mouth blowing (in a gaseous state) exists, the characteristic C-H stretch absorption bands in CH3 and CH2 functional groups in ethanol (CH3CH2OH) appear at a wave length of λ = 3.42 µm. To investigate the presence of ethyl alcohol in exhaled human air, the light beam of λ = 3.42 µm is passing through an air sample. If one alternately measures the intensity of the investigated beam and the reference, a percentage of ethanol in the air sample can be estimated using a sensitive nondispersive infrared (NDIR) system with a stable operating flow mass detector. To eliminate a mechanical chopper and noise generating stepper motors, a photonic chopper as a liquid crystal shutter for λ = 3.42 µm has been designed. For this purpose, an innovative infrared nematic liquid crystal mixture was intentionally prepared. The working mixture was obtained by a selective removal of C-H bonds and its exchange by heavier polar substituents, what ensures a lack of absorption band of C-H bonds. The paper presents theory, concept and final experimental results of the infrared nematic liquid crystals mixture and the liquid crystal shutter for breathalyzer applications.

2

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.

3

Immunomodulacyjne właściwości mikroorganizmów

Ograczyk E., Micota B., Miszczyk E., Gajewski E., Włodarczyk M., Rudnicka K., Sadowska B.

LAB Laboratoria, Aparatura, Badania

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2015

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R. 20, nr 3

11--18

4

Transparent laser damage resistant nematic liquid crystal cell “LCNP3”

Raszewski Z., Piecek W., Jaroszewicz L., Dąbrowski R., Nowinowski-Kruszelnicki E., Soms L., Olifierczuk M., Kędzierski J., Morawiak P., Mazur R., Miszczyk E., Mrukiewicz M., Kowiorski K.

Opto-Electronics Review

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2014

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Vol. 22, No. 3

196-200

EN

There exists the problem in diagnostics of dense plasma (so-called Thomson diagnostics). For this purpose the plasma is illuminated by series of high energy laser pulses. The energy of each separate pulse is as large as 3 J, so it is impossible to generate a burst of such pulses by a single laser. In this situation, the pulses are generated by several independent lasers operating sequentially, and these pulses are to be directed along the same optical path. To form an optical path with ʎ = 1.064 μm and absolute value of the laser pulse energy of 3 J, a special refractive index matched twisted Nematic Liquid Crystal Cell of type LCNP3, with switching on time ƮON smaller than 3 μs was applied.

5

Optical properties of a liquid crystal with small ordinary and extraordinary refractive indices and small optical anisotropy

Kędzierski J., Garbat K, Raszewski Z., Kojdecki M. A., Kowiorski K., Jaroszewicz L. R., Miszczyk E., Dąbrowski R., Zieliński J., Piecek W.

Opto-Electronics Review

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2014

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Vol. 22, No. 3

162-165

EN

Optical properties of a nematic liquid crystal with small refractive index and small birefringence were studied. The ordinary and extraordinary refractive indices and birefringence were measured as functions of temperature by using an Abbe refractometer and wedge nematic cells. From values of these indices the nematic orientational order parameter was calculated by using several methods and corresponding mathematical models. Kuczyński et al. method was found to be suitable for determining the order parameter also for materials featuring small ordinary refractive index, with unknown density.

6

Measurement of elastic constants of nematic liquid crystals with use of hybrid in-plane-switched cell

Nowinowski-Kruszelnicki E., Kędzierski J., Raszewski Z., Jaroszewicz L., Kojdecki M. A., Piecek W., Perkowski P., Olifierczuk M., Miszczyk E., Ogrosnik K., Morawiak P.

Opto-Electronics Review

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2012

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Vol. 20, No. 3

255-259

EN

A new method for quick and pretty accurate measurements of splay, twist and bend elastic constants of nematic liquid crystals is experimentally verified. The main concept relies on exploiting only the electric field and determining magnitudes of nematic elastic constants from threshold fields for Freedericksz transitions in only one hybrid in-plane-switched cell. In such cell the deformations of an investigated liquid crystal are controlled by three separated pairs of electrodes confining measurement domains. In two of them inter-digital electrodes are mounted on one cell cover. Splay, twist and bend elastic constants can be measured by a proper choice of electrodes' configuration together with orienting cover coatings (without applying magnetic fields). In this paper, we describe layout of our cells and results of experimental tests by using different liquid crystals: 5CB and 6CHBT (with positive dielectric anisotropy), Demus' esters (with negative dielectric anisotropy) and new liquid crystals mixtures produced in our university.

7

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.

8

High birefringence liquid crystal mixtures for electro-optical devices

Nowinowski-Kruszelnicki E., Kędzierski J., Raszewski Z., Jaroszewicz L., Kojdecki M., Piecek W., Perkowski P., Garbat K., Olifierczuk M., Sutkowski M., Ogrodnik K., Morowiak P., Miszczyk E.

Optica Applicata

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2012

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Vol. 42, nr 1

167--180

EN

High-birefringence nematic liquid crystals recently developed in the Military University of Technology (Poland) are examined for selected physical properties. In particular, for six liquid crystal mixtures there were determined: two components of dielectric permittivity for voltage frequencies in the range from 10 Hz to 10 MHz; rotational viscosity; splay, twist and bend elastic constants; ordinary and extraordinary refractive indices for light wavelengths in the range from 0.3 ?m to 1.6 ?m. The properties are discussed in terms of applicability of the new liquid crystals to electro-optical devices.

9

Determination of ordinary and extraordinary refractive indices of nematic liquid crystals by using wedge cells

Kędzierski J., Raszewski Z., Kojdecki M. A., Kruszelnicki-Nowinowski E., Perkowski P., Piecek W., Miszczyk E., Zieliński J., Morawiak P., Ogrodnik K.

Opto-Electronics Review

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2010

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Vol. 18, No. 2

214-218

EN

A new accurate and fast interference method for determining ordinary and extraordinary refractive indices of nematic liquid crystals is presented and discussed. The method relies on microscopic measurements of distances between interference fringes appearing in polarised parallel coherent monochromatic light beam transmitted normally to the surfaces through a wedge cell filled with a nematic. Both glass plates confining the cell are coated with a partly transparent thin film of metal which is deposited by evaporation in vacuum. Owing to the multiple reflections between the surfaces and a small edge angle, the interference fringes observed near the wedge apex edge are sharp and equidistant. To apply this method one needs only small amount of an investigated liquid crystal. Basic mathematical formulae and results of an experiment are briefly discussed.

10

Study of anchoring characteristics and splay-bend elastic constant based on experiments with non-twisted nematic liquid crystal cells

Kędzierski J., Kojdecki M. A., Raszewski Z., Rutkowska J., Piecek W., Perkowski P., Zieliński J., Miszczyk E.

Opto-Electronics Review

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2008

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Vol. 16, No. 4

390-394

EN

Possible influence of a nematics splay-bend elastic constant and corresponding free energy functional term on adequacy of description of nematics states is studied by comparing results of theoretical considerations and computer simulations with experimental data. Planar deformation states enforced in flat nematics cells by symmetric aligning cover coatings and external electric or magnetic fields are studied in one-dimensional approximation. Nematics material parameters and nematics-substrate coupling characteristics are determined from experimental data by immediate measurement or by solving inverse problems. Two series of cells with thicknesses between twenty and forty-four micrometers (in fact two wedge cells) with two different orienting substrates are investigated by measuring a cell optical response in a birefringence experimental system. Good agreement between optical retardation measured and simulated is observed. Posterior comparison of free energy contributions from substrate interactions and a hypothetical surface-like term leads to a conclusion that the last one together with a splay-bend elastic constant should be very small and can be neglected.

11

Optical method for determining anisotropy of diamagnetic susceptibility of nematic and polar anchoring energy coefficient of nematic-substrate systems by using a cell of varying thickness

Kędzierski J., Raszewski Z., Kojdecki M., Zieliński J., Miszczyk E., Lipińska L.

Opto-Electronics Review

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2004

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Vol. 12, No. 3

299-303

EN

A wedge cell of the wedge angle of the order of few milliradians was used to measure threshold magnetic fields for the magnetic Freedericksz transition [1-3]. A nematic liquid crystal filling the cell was of planar orientation enforced by the treatment of the flat boundary plates. A system of interference fringes appeared in the cell placed in normally incident light between analyser and polariser crossed. In the vicinity of each fringe, the cell could be considered as a flat-parallel one and hence it was equivalent to a system of flat cells of different precisely determined thickness, the same relates to any cell of slowly-varying thickness and flat cover plates. The threshold magnetic field magnitudes were interpreted as eigenvalues of the boundary eigenvalue problem for the operator of the second derivative; the interaction between the nematics and the substrate was described by the Rapini-Papoular formula [3] (i.e., weak coupling was considered). The resulting formulae were used to determine the polar anchoring energy coefficient and the anisotropy of diamagnetic susceptibility after the threshold fields measured. The method was applied to characterise the nematic liquid crystal 5CB and the coupling between it and the substrates made of poly(amic acid) MP2 [4, 5]. The estimates of material parameters agreed pretty well with those determined by the composite method [6].

12

The order parameter of liquid-crystalline mixture with dichroic dye for TN LCD

Olifierczuk M., Kędzierski J., Raszewski Z., Zieliński J., Miszczyk E.

Biuletyn Wojskowej Akademii Technicznej

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1999

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Vol. 48, nr 4

99-106

EN

Paper contains results of studies on TL LC mixture with a black dichroic dye. The general information concerning a principle of an action of TN display with the dye is presented. The effect of the dye on temperature dependence of LC order parameter is discussed. The order parameter is confirmed by several methods (Lorentz-Lorenz's, Vuks-Chandrasekhar-Madhusudana's, Neugebauer-Saupe-Maier's procedures and extrapolation by Haller and Subramhanyam) for PCB.

PL

Praca zawiera wyniki badań nad efektem TN z czarnym barwnikiem dichroicznym. Podane są ogólne informacje na temat zasady działania displeja TN z barwnikiem chroicznym. Przedyskutowano wpływ barwnika na temperaturową charakterystykę parametru uporządkowania warstwy. Parametr uporządkowania otrzymano różnymi metodami (procedury Lorentz-Lorenz, Vuks-Chandrasekhar-Madhusudana, Neugebauer-Saupe-Maier i ekstrapolacje Hallera i Subramhanyamy) i sprawdzono dla PCB.