Reference : Chiral Nematic Liquid Crystal Microlenses
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
Physics and Materials Science
Chiral Nematic Liquid Crystal Microlenses
Popov, Piotr mailto [Kent State University > Department of Physics]
Honaker, Lawrence William mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit > ; Kent State University > Liquid Crystal Institute]
Mirheydari, Mona mailto [Kent State University > Department of Physics]
Mann, Elizabeth K. mailto [Kent State University > Department of Physics]
Jákli, Antal mailto [Kent State University > Liquid Crystal Institute]
Scientific Reports
Nature Publishing Group
Yes (verified by ORBilu)
United Kingdom
[en] liquid crystal ; lens ; physics ; chirality ; material ; microlens ; Pancharatnam
[en] Nematic liquid crystals (NLCs) of achiral molecules and racemic mixtures of chiral ones form flat films and show uniform textures between circular polarizers when suspended in sub-millimeter size grids and immersed in water. On addition of chiral dopants to the liquid crystal, the films exhibit optical textures with concentric ring patterns and radial variation of the birefringence color. Both are related to a biconvex shape of the chiral liquid crystal film; the rings are due to interference. The curvature radii of the biconvex lens array are in the range of a few millimeters. This curvature leads to a radial variation of the optical axis along the plane of the film. Such a Pancharatnam-type phase lens dominates the imaging and explains the measured focal length of about one millimeter. To our knowledge, these are the first spontaneously formed Pancharatnam devices. The unwinding of the helical structure at the grid walls drives the lens shape. The relation between the lens curvature and material properties such as helical pitch, the twist elastic constant, and the interfacial tensions, is derived. This simple, novel method for spontaneously forming microlens arrays can also be used for various sensors.
National Science Foundation - NSF
Researchers ; Professionals ; Students

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