References of "Geng, Yong"
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See detailElucidating the fine details of cholesteric liquid crystal shell reflection patterns
Geng, Yong; Noh, Junghyun UL; Drevensek-Olenik, Irena et al

in Liquid Crystals (2017), 44(12-13),

Clusters of planar-aligned short-pitch cholesteric liquid crystal spheres generate dynamic colourful patterns due to multiple selective reflections from the radially oriented cholesteric helices in ... [more ▼]

Clusters of planar-aligned short-pitch cholesteric liquid crystal spheres generate dynamic colourful patterns due to multiple selective reflections from the radially oriented cholesteric helices in neighbour shells at varying distances. These photonic communication patterns were widely investigated for the cases of both droplets and shells, demonstrating not only intriguing optical phenomena but also potential for applications as new optical elements for photonics, sensing or security pattern generation. However, the optics of these clusters is truly complex and until now only the strongest and most fundamental reflections have been analysed and explained. In this report, we elucidate the origin of a number of more subtle reflections and we explain the extension in space of various spots as well as their internal colour variations. [less ▲]

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See detailSecurity in the Shell : An Optical Physical Unclonable Function made of Shells of Cholesteric Liquid Crystals
Lenzini, Gabriele UL; Samir, Ouchani; Roenne, Peter UL et al

in Proc. of the 9th IEEE Workshop on Information Forensics and Security (2017, October 02)

We describe the application in security of shells of Cholesteric Liquid Crystals (ChLCs). Such shells have a diameter in the microns range and can be gathered in hundreds in a surface area as small as a ... [more ▼]

We describe the application in security of shells of Cholesteric Liquid Crystals (ChLCs). Such shells have a diameter in the microns range and can be gathered in hundreds in a surface area as small as a nail’s head. Because of their structural properties, a bundle of them reflects light, creating colorful patterns that we argue to be unique and computationally hard to predict. We argue also that the bundle itself is unclonable. These are typical properties of Physically Unclonable Functions, a family to which shells of ChLCs belong too. Herein we discuss their physical and security properties and their potential use in object authentication. [less ▲]

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