Liquid crystal-bead reflectors illuminating the needle in the haystack (LAB RINTH)
Abstract
This project is focused on research to explore spherical shells of cholesteric liquid crystal (CLC), from both a fundamental and applied science perspective. Liquid crystals are anisotropic liquids, in which the molecules making up the phase spontaneously develop long-range orientational order, despite being fluid and thus can be easily processed. CLCs have special properties which allows the directions in which their molecules align can be modulated, into a helical superstructure, with a periodicity that can be tuned from the range from around the 100nm range to several microns. The combination of spherical symmetry and the unique photonic performance of CLCs turn these shells into extremely interesting optical components: they reflect back an incoming signal to the source regardless of how the source is oriented with respect to the shells, but they do so only if the signal has the right wavelength and the right circular polarization. This allows them to be easily identified even in a very complex background. These CLCs can avail themselves to a range of potential interest. A focal point application for this project is centered on the potential use of the CLCs for low-energy continuous and rapid peer-to-peer communication between swarm units, providing each unit with the locations, distances, and directions of its neighbors, preferably uniquely identified. Basically the CLC shell reflectors have the potential to provide the infrastructure for rapid relative localization within flocking swarms via direct optical peer-to-peer communication. Also, by labelling each unit with a unique tag, or even completely covering a robot~s surface with a unique CLC reflector arrangement (easily achieved by randomizing the arrangement of CLC reflectors of a few different types, varying in reflection wavelength and polarization), the ID and the relative position of neighboring units can be obtained using regular photography and rather simple image processing. The three main goals of this project are: a. Establish a quantitative understanding of how CLC shell reflection patterns change when viewed over long distances, with arbitrary illumination and observation directions, and with arbitrary 3D arrangements of the CLC shell reflectors; b. Develop portable optical equipment for illuminating objects carrying CLC shells and/or reading off their optical response, in realistic conditions corresponding to scenarios where the CLC shells would be used in search and rescue or other types of identification tasks, also at large distances; c. Assess the ability of CLC shell reflectors to aid easy detection of targets in complex backgrounds thanks to the selective reflection properties of CLCs (circular polarization, reflection only in a narrow wavelength band).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 15, 2019
- Source ID
- N629091912093
Entities
People
- Jan Lagerwall
Organizations
- Office of Naval Research
- United States Navy