Chiral Liquid Crystal Lenses Confined in Microchannels
It is known that the liquid crystalline smectic-A phase has geometric defects, called focal conic domains, which can be used as gradient-index microlenses. Cholesteric (chiral nematic) phases also have topological defects with a central symmetry and a singularity at their center. We explore a weakly...
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| Format: | Article |
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MDPI AG
2020-08-01
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| Series: | Materials |
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| Online Access: | https://www.mdpi.com/1996-1944/13/17/3761 |
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| author | Sean M. Hare Beatrice Lunsford-Poe MinSu Kim Francesca Serra |
| author_facet | Sean M. Hare Beatrice Lunsford-Poe MinSu Kim Francesca Serra |
| author_sort | Sean M. Hare |
| collection | DOAJ |
| description | It is known that the liquid crystalline smectic-A phase has geometric defects, called focal conic domains, which can be used as gradient-index microlenses. Cholesteric (chiral nematic) phases also have topological defects with a central symmetry and a singularity at their center. We explore a weakly chiral system in which both types of defects can be present in the same material at different temperatures, and with this strategy we create lenses whose focal length is tunable with temperature. We measure the focal length of the tunable lenses, and we investigate the behavior of the defects near the phase transition. We identify the experimental conditions that make the simultaneous presence of the smectic focal conic domains and the circular cholesteric domains possible, such as the concentration of chiral dopant and the rate of heating and cooling. The transformation of focal conic domains into circular cholesteric domains is a new example of memory at the phase transition between smectic-A and nematic liquid crystals. |
| first_indexed | 2024-03-10T16:49:39Z |
| format | Article |
| id | doaj.art-461ce0dc8c7e4ad3a609676f0a4d547b |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T16:49:39Z |
| publishDate | 2020-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-461ce0dc8c7e4ad3a609676f0a4d547b2023-11-20T11:21:44ZengMDPI AGMaterials1996-19442020-08-011317376110.3390/ma13173761Chiral Liquid Crystal Lenses Confined in MicrochannelsSean M. Hare0Beatrice Lunsford-Poe1MinSu Kim2Francesca Serra3Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USADepartment of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USADepartment of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USADepartment of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USAIt is known that the liquid crystalline smectic-A phase has geometric defects, called focal conic domains, which can be used as gradient-index microlenses. Cholesteric (chiral nematic) phases also have topological defects with a central symmetry and a singularity at their center. We explore a weakly chiral system in which both types of defects can be present in the same material at different temperatures, and with this strategy we create lenses whose focal length is tunable with temperature. We measure the focal length of the tunable lenses, and we investigate the behavior of the defects near the phase transition. We identify the experimental conditions that make the simultaneous presence of the smectic focal conic domains and the circular cholesteric domains possible, such as the concentration of chiral dopant and the rate of heating and cooling. The transformation of focal conic domains into circular cholesteric domains is a new example of memory at the phase transition between smectic-A and nematic liquid crystals.https://www.mdpi.com/1996-1944/13/17/3761liquid crystalsmicro-lensesphase transition |
| spellingShingle | Sean M. Hare Beatrice Lunsford-Poe MinSu Kim Francesca Serra Chiral Liquid Crystal Lenses Confined in Microchannels Materials liquid crystals micro-lenses phase transition |
| title | Chiral Liquid Crystal Lenses Confined in Microchannels |
| title_full | Chiral Liquid Crystal Lenses Confined in Microchannels |
| title_fullStr | Chiral Liquid Crystal Lenses Confined in Microchannels |
| title_full_unstemmed | Chiral Liquid Crystal Lenses Confined in Microchannels |
| title_short | Chiral Liquid Crystal Lenses Confined in Microchannels |
| title_sort | chiral liquid crystal lenses confined in microchannels |
| topic | liquid crystals micro-lenses phase transition |
| url | https://www.mdpi.com/1996-1944/13/17/3761 |
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