Optical wireless (OW) technology has attracted significant interest for indoor positioning in the past decade. An emerging form of this technology makes use of angle-of-arrival (AOA) measurements to carry out positioning via triangulation off of an optical beacon grid. Such AOA-based OW positioning systems can yield accurate position estimates-but only given sufficient attention to the optical receiver. The design, operation, and implementation of such a receiver is presented in this work. The optical receiver is designed to have a sufficiently small AOA error, being AOA = 1°, over a wide angular field-of-view (FOV), being 100°. The design allows the optical receiver to carry out positioning based off a 3 × 3 grid of optical beacons, where each optical beacon is uniquely identified using multiple frequency and colour channels. The optical beacons are widely spaced to fully utilize the optical receiver's wide angular FOV. The overall AOA-based OW positioning system exhibits a position error of 1.7 cm, which is comparable to those obtained by more complex positioning systems. Thus, the presented AOA-based technologies can play a role in emerging indoor positioning systems.
The proposed work introduces time-captured Raman and terahertz spectroscopic analyses as orthogonal probes of intramolecular and intermolecular modes in biomolecular structures. The work focuses on glucose given the complexity and dynamics of its anomeric conversion and crystallization. The Raman analyses capture the dynamics of its intramolecular modes – revealing conversion between α and β anomers. At the same time, the terahertz analyses capture the dynamics of its intermolecular modes – showing an evolution from amorphous to crystalline morphology. It is shown that time-captured Raman and terahertz spectroscopy together render a more complete depiction, and deeper understanding, of the biomolecular structure of glucose.
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