Liquid crystals (Print)最新文献

{"title":"Heat transfer augmentation using liquid crystal","authors":"M. Wierzbowski, J. Stasiek","doi":"10.1117/12.472189","DOIUrl":"https://doi.org/10.1117/12.472189","url":null,"abstract":"A visualization technique is used to measure the heat transfer to a plane surface with obstacles. Liquid crystal coated on a mylar sheet is used to locate isotherms on a cooled plate. The isotherms on the plate surface are recorded by JVC-camera and true-color image processing system. Experimental procedure cover full-field flow patterns in heat exchanger element (flat plate with discs in-line, staggered and with vortex generators) describing local heat transfer coefficient and Nusselt number on the surface.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114893728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Significance of reflection reduction in a TN display for color visualization","authors":"M. Olifierczuk, J. Zieliński","doi":"10.1117/12.472186","DOIUrl":"https://doi.org/10.1117/12.472186","url":null,"abstract":"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 color image. We have done mathematical and numerical analyses of a propagation of light wave through LC displays with antireflective layer, glass planes, conductive layers, liquid crystal layer and polarizers. 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.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114951058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Langmuir film formation ability of liquid crystals with -CN an -NCS terminal group","authors":"R. Hertmanowski, T. Martyński, D. Bauman","doi":"10.1117/12.472154","DOIUrl":"https://doi.org/10.1117/12.472154","url":null,"abstract":"Surface pressure-mean molecular area isotherms of Langmuir films of some liquid crystals with CN or --NCS terminal group as well as of their binary mixtures have been recorded. It was found that only the liquid crystals which molecules have CN group are able to form a stable monolayer at the air-water interface. Information about the molecular organization and intermolecular interaction in two dimensional layer has been obtained. Moreover, the miscibility or phase separation of two components in the mixtures of various compositions has been determined by using excess area criterion and surface phase rule.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116459096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical modeling of LCD electro-optical performance","authors":"Henning Woehler, M. E. Becker","doi":"10.1117/12.472176","DOIUrl":"https://doi.org/10.1117/12.472176","url":null,"abstract":"Realization of complex high information density LCDs and systematic optimization of their electro-optical and ergonomic performance would not be possible in the required time-frame without reliable numerical modeling of the electro-optical performance of such display devices. In this paper we outline the history of numerical LDC modeling starting with Berreman and van Doorn, finally arriving at modern state-of-the-art LCD-modeling in two and three dimensions. Numerical modeling of LCDs is carried out in two steps: first, the effect of the electrical field on the orientation of the liquid crystalline alignment has to be evaluated before the corresponding optical properties can be computed. Starting from LC-elasticity theory we present suitable numerical methods for computing various states of LC-deformation (stable, metastable, bistable, etc.) in one- dimensional problems Light propagation in layered anisotropic absorbing media is evaluated with methods that are based on Maxwell's equations (Berreman 4 X 4-matrix approach). This approach can be simplified to yield methods with reduced computing time and sufficient accuracy for many problems (e.g. extended Jones 2 X 2-matrix formalism). A finite element method with automatic mesh generation and refinement for computing accurate solutions in two- dimensional problems is presented and its application illustrated with examples (e.g. IPS-effect, VAN-cells, etc.). In two- and three-dimensional problems, i.e. in cells with lateral dimensions comparable to the cell thickness, a variety of different director configurations are possible for a given geometry and electrical driving and addressing, making the modeling more complicated. Moreover, local defects can occur, which should also be considered in the simulation. Suitable approaches for the director field calculation, i.e. the vector and the tensor approach, are discussed. The complexity of the problem increases considerably when a third dimension is added, e.g. the geometry of the problem has to be defined in three dimensions together with the respective boundary conditions (anchoring geometry and elasticity) and electrodes. If strong deformations or even distortions are present in the orientation of the LC-layer, the applicability of known one- dimensional approaches for computing the optical properties must be checked and new approaches eventually have to be developed. The third dimension prohibits the use of some standard methods (e.g. FDTD), solely because of the enormous memory requirements and the long calculation times. Other approaches are presented and discussed.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129836731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LC display for Polish gliders PW-5 and PW-6","authors":"J. Parka, E. Nowinowski-Kruszelnicki, S. Kłosowicz, J. Zieliński, J. Żmija","doi":"10.1117/12.472193","DOIUrl":"https://doi.org/10.1117/12.472193","url":null,"abstract":"The liquid crystal display dashboard for polish gliders PW-5 and PW-6 have been presented. The measuring flight parameters system and electronic scheme of the glider have been proposed, developed and tested. Laboratory investigations of the board flight parameters and their compatibility with standards have been described.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126992190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of AFLCs using Fabry-Perot etalon","authors":"Sureshchandra J. Gupta, Rita Amar-Gharde, A. Tripathi","doi":"10.1117/12.472136","DOIUrl":"https://doi.org/10.1117/12.472136","url":null,"abstract":"The spectroscopic technique using the Fabry-Perot [FPSS] etalon coupled with a spectrometer has been used to determine the mesophase transition temperatures of the samples (1) MHPB(H)PBC (2) MHPB(Cl)PBC. Earlier FPSS work on the sample MHPOBC(R) is also substantiated here with results from Differential Scanning Calorimetery [DSC] and Polarization Microscopy Studies [PMS]. A comparison of the results obtained with those of DSC clearly indicates the success of the FPSS technique in determining the transition temperatures of the above samples belonging to the FLCs and AFLCs groups. The photographs of the textures using PMS also support the above results. This novel technique has led to the detection of new mesophase transitions in addition to those reported by DSC and PMS. These new findings are also corroborated by the analysis of the thermal runs using DSC and the textures from PMS.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123341473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluorinated banana-shaped 1,2,4-oxadiazoles","authors":"L. Karamysheva, I. F. Agafonova, T. Geivandova, S. Torgova, M. Becchi","doi":"10.1117/12.472199","DOIUrl":"https://doi.org/10.1117/12.472199","url":null,"abstract":"A series of banana-shaped diesters derivated of 3,5-bis-(p- hydroxyphenyl)-1,2;4-oxadiazole and p-alkyloxy- fluoro(difluoro)benzoic acids were synthesized and investigated by optical microscopy and DSC method. The influence of the alkyloxy-substituent lengths and of the F- group position in the molecule on its mesomorphic properties is discussed.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114723164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of molecular architecture on liquid crystalline properties of cyclosiloxanes","authors":"J. Sołtysiak, E. Białecka-Florjańczyk, E. Kowalczyk, T. Ganicz, I. Śledzińska, J. Przedmojski, E. Bednarek","doi":"10.1117/12.472130","DOIUrl":"https://doi.org/10.1117/12.472130","url":null,"abstract":"A series of new liquid crystalline cyclic siloxane hexamers was prepared to investigate the influence of the molecular structure of the mesogenic side group on their mesomorphic behavior. Preliminary studies of properties of cyclic siloxanes bearing the various mesogenic side group by means of polarized optical microscopy differential scanning calorimetry and X-Ray diffraction are reported.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121452991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Orientation of a nematic liquid crystal near a polymer layer determined by Fourier transform infrared spectroscopy","authors":"P. Gautier, S. Araki, T. Miyashita, T. Uchida","doi":"10.1117/12.472163","DOIUrl":"https://doi.org/10.1117/12.472163","url":null,"abstract":"The comprehension of the mechanism of alignment of a liquid crystal by a rubbed polymer layer is a current interest from a fundamental point of view but also in regards to applications. To understand the mechanism of alignment it is necessary to clarify how the liquid crystal is oriented near a surface. A nematic liquid crystal (LC) has a longer a uniaxial symmetry near a rubbed polymer surface but exhibits a biaxial orientation. We probed the thickness dependence of the orientation of a LC using Fourier Transform Infrared Spectroscopy. By this method it can be shown that the order parameter is lower near the surface than in the bulk and that the symmetry of a nematic liquid crystal close to the surface of the alignment layer is not longer uniaxial.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"242 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132519623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and liquid-crystalline behaviour of thia-bridged tetra- and octa-substituted phthalocyanine derivatives","authors":"A. Guerek, M. Durmuş, V. Ahsen","doi":"10.1117/12.472122","DOIUrl":"https://doi.org/10.1117/12.472122","url":null,"abstract":"Thia-bridged tetra- and octa-poly(oxyethylene)-substituted metal free- and Ni(II) phthalocyanines have been synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt (NiCl2) or a strong organic base. The new compounds have been characterized by elemental analyses, UV/vis, IR, NMR and mass spectra. The mesogenic properties of these new materials were studied by differential scanning calorimetry (DSC), optical microscopy and X-ray investigations. Although octa-substituted phthalocyanine derivatives are liquid all tetra-substituted compounds show a discotic mesophase in an extremely large temperature interval including room temperature. The relationship between the structure of the mesogenic units and the mesogenic behavior is discussed and the influence of the presence of the different heteroatoms in the side chains on mesomorphic properties has been determined.","PeriodicalId":132866,"journal":{"name":"Liquid crystals (Print)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127198136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}