Scanning the issue: T-ray imaging, sensing, and retection

Copyright © 2007 IEEEDerek Abbott, Xi-Cheng Zhan

Terahertz optical fibers [Invited]

Abstract not available.Md. Saiful Islam, Cristiano M.B. Cordeiro, Marcos A.R. Franco, Jakeya Sultana, Alice L.S. Cruz, and Derek Abbot

Monte Carlo Method with Heuristic Adjustment for Irregularly Shaped Food Product Volume Measurement

Volume measurement plays an important role in the production and processing of food products. Various methods have been proposed to measure the volume of food products with irregular shapes based on 3D reconstruction. However, 3D reconstruction comes with a high-priced computational cost. Furthermore, some of the volume measurement methods based on 3D reconstruction have a low accuracy. Another method for measuring volume of objects uses Monte Carlo method. Monte Carlo method performs volume measurements using random points. Monte Carlo method only requires information regarding whether random points fall inside or outside an object and does not require a 3D reconstruction. This paper proposes volume measurement using a computer vision system for irregularly shaped food products without 3D reconstruction based on Monte Carlo method with heuristic adjustment. Five images of food product were captured using five cameras and processed to produce binary images. Monte Carlo integration with heuristic adjustment was performed to measure the volume based on the information extracted from binary images. The experimental results show that the proposed method provided high accuracy and precision compared to the water displacement method. In addition, the proposed method is more accurate and faster than the space carving method

OCM 2013 - 1st International Conference on Optical Characterization of Materials: March 6th - 7th, 2013, Karlsruhe, Germany

The state of the art in optical characterization of materials is advancing rapidly. New insights into the theoretical foundations of this research field have been gained and exciting practical developments have taken place, both driven by novel applications that are constantly emerging. This book presents latest research results in the domain of Characterization of Materials by spectral characteristics of UV (240 nm) to IR (14 µm), multispectral image analysis, X-Ray, polarimetry and microscopy

OCM 2013 - Optical Characterization of Materials - conference proceedings

The state of the art in optical characterization of materials is advancing rapidly. New insights into the theoretical foundations of this research field have been gained and exciting practical developments have taken place, both driven by novel applications that are constantly emerging. This book presents latest research results in the domain of Characterization of Materials by spectral characteristics of UV (240 nm) to IR (14 µm), multispectral image analysis, X-Ray, polarimetry and microscopy

Design and Analysis of Advanced Photonic Devices for Electromagnetic Transmission and Sensing

In this thesis, we report the investigation of advanced photonic devices for electromagnetic transmission and biochemical sensing in the terahertz and optical regimes. The choice of material for designing a terahertz device is deemed to be one of the most crucial factors. First, we consider materials that are frequently used in making terahertz devices. We experimentally demonstrate the optical, thermal, and chemical properties of various chosen glasses, polymers, and resin to select the optimal material for terahertz. Second, we perform a broad review on terahertz optical fibres—this includes various fibre categories, their guiding mechanisms, fabrication methodologies, possible experimental methodologies, and applications. Third, we analyse and demonstrate the design of various fibre structures for terahertz transmission and sensing, and then perform experiments on a hollow core antiresonant fibre. We demonstrate successful fabrication of an asymmetrical Zeonex fibre using a novel fabrication method. This is carried out by using a tabletop horizontal extruder designed for producing polymer filaments. The fabricated fibre is then experimentally investigated for terahertz transmission and gas sensing. Fourth, we study optical fibre based surface plasmon resonance biosensors for operation in the optical regime. Theoretical studies are undertaken to obtain the best possible sensor in consideration of performance, experimental feasibility, and fabrication. One of the optimized sensors is then fabricated as a possible candidate for possible realworld sensing applications. Finally, we study metasurface planar devices for achieving high sensitivity and quality factor in the terahertz regime. We first demonstrate a tunable graphene metasurface that can achieve multi-band absorption and high refractometric sensing. Later, we demonstrate on an all-dielectric metasurface that reports highest Q-factor in the terahertz regime. We fabricate and experiment on the dielectric metasurface and find good agreement with the simulation.Thesis (Ph.D.) -- University of Adelaide, School of Electrical & Electronic Engineering, 202

Terahertz Hollow Core Antiresonant Fibre

Research on fibres operating in the terahertz frequency range is rapidly growing with numerous potential applications such as in spectroscopy, imaging, security, and transmission. However, designing a terahertz fibre with controllable and desirable transmission characteristics is challenging due to the complex cladding structure. In this thesis, we study hollow core antiresonant photonic crystal fibre (HC-ARPCF) for electromagnetic transmission and refractometric sensing in the terahertz regime. The HC-ARPCF consists of an air-core surrounded by a structured polymer cladding, which confines most of the power within the air-core region. The idea behind hollow-core antiresonant fibres is that light is guided in the hollow air core, thus drastically reducing the transmission loss. Guidance of light is achieved via reflection provided by thin membranes of the antiresonant tubes that surround the core, behaving effectively as a Fabry-P´erot cavity. At antiresonant frequencies, the thin membranes reflect the light towards the core because of the higher refractive index of the membranes. The guidance mechanism of the HC-ARPCF can also be explained due to the inhibited coupling mechanism (coupling between core and cladding mode is forbidden in guidance), where the cladding mode maintains a lower density of states (ηeff) than the fundamental core mode. Inhibited coupling guidance in HC-ARPCF offers broad bandwidth. At resonance frequencies, the light couples to the thin membranes and the core mode becomes more lossy, which can assist in gas sensing. The idea for the terahertz HC-ARPCF is inspired by those in the well-developed infrared and mid-infrared range. The effect of cladding pattern, cladding material, and cladding sector angle are analysed to investigate and tune the transmission loss, bending loss, and modal properties. The detailed simulations of several designs give a new understanding of the effect of the cladding elements on the leakage loss. The HCARPCFs are considered as a suitable candidate for low loss and broadband terahertz transmission. In addition, we model and simulate a simple hollow-core antiresonant terahertz waveguide, show the linear properties and explore the mechanism of achieving nonlinearity. First, the linear properties of HC-ARPCF are discussed, and then the nonlinear properties of the same structure are demonstrated, considering a gas-filled core in the terahertz regime. Furthermore, this thesis describes two different fabrication techniques for terahertz HC-ARPCF, using Zeonex and UV-resin as the bulk materials via a 3D printing process. The Zeonex filaments are made by using a Filabot EX2 Filament Extruder designed for filament production. To measure the effective material loss of the Zeonex, a circular disc with an uneven thickness of 0.65±0.05mmand a diameter of 24mmis printed.We demonstrate the first successful fabrication of Zeonex and UV resin fibre using Fused Decomposition modelling (FDM) and Steriolithography Apparatus (SLA) methods, respectively, to investigate the surface quality and thickness variations of the printed structure. These printing approaches have potential to replace conventional costly terahertz fibre drawing process. The fabricated fibres are then experimentally investigated for terahertz transmission. Fibres fabricated using the FDM and SLA methods are also investigated numerically and the results are compared against the experimental results. The detailed simulations suggest their attenuation can be improved by orders of magnitude with improvements in the quality of the fabrication process. We also discuss the possible post-processing techniques that can be useful for improving fibre quality and consistency in future work.Thesis (Ph.D.) -- University of Adelaide, School of Electrical & Electronic Engineering, 202

X-Ray astronomy the 1980's

The status of the current understanding of important problems to which X-ray astronomical techniques can be applied is summarized and the prospects for such research in the future is discussed. Relatively near-term X-ray astronomical research objectives are presented. The importance of a continuing program of balloon-borne research as a cost effective means by which studies at energies in excess of 20 keV may be performed is emphasized. The scientific opportunities presented by the Space Transpotation System to develop low cost experiments which are beyond the scope of balloon-borne capabilities are also highlighted