All-Metal Terahertz Metamaterial Absorber and Refractive Index Sensing Performance
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EPA Handbook: Optical and Remote Sensing for Measurement and Monitoring of Emissions Flux of Gases and Particulate Matter
EPA Handbook: Optical and Remote Sensing for Measurement and Monitoring of Emissions Flux of Gases and Particulate Matter EPA 454/B-18-008 August 2018 EPA Handbook: Optical and Remote Sensing for Measurement and Monitoring of Emissions Flux of Gases and Particulate Matter U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Air Quality Assessment Division Research Triangle Park, NC EPA Handbook: Optical and Remote Sensing for Measurement and Monitoring of Emissions Flux of Gases and Particulate Matter 9/1/2018 Informational Document This informational document describes the emerging technologies that can measure and/or identify pollutants using state of the science techniques Forward Optical Remote Sensing (ORS) technologies have been available since the late 1980s. In the early days of this technology, there were many who saw the potential of these new instruments for environmental measurements and how this technology could be integrated into emissions and ambient air monitoring for the measurement of flux. However, the monitoring community did not embrace ORS as quickly as anticipated. Several factors contributing to delayed ORS use were: • Cost: The cost of these instruments made it prohibitive to purchase, operate and maintain. • Utility: Since these instruments were perceived as “black boxes.” Many instrument specialists were wary of how they worked and how the instruments generated the values. • Ease of use: Many of the early instruments required a well-trained spectroscopist who would have to spend a large amount of time to setup, operate, collect, validate and verify the data. • Data Utilization: Results from path integrated units were different from point source data which presented challenges for data use and interpretation. -
Plasmonic and Metamaterial Structures As Electromagnetic Absorbers
Plasmonic and Metamaterial Structures as Electromagnetic Absorbers Yanxia Cui 1,2, Yingran He1, Yi Jin1, Fei Ding1, Liu Yang1, Yuqian Ye3, Shoumin Zhong1, Yinyue Lin2, Sailing He1,* 1 State Key Laboratory of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, China 2 Key Lab of Advanced Transducers and Intelligent Control System, Ministry of Education and Shanxi Province, College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan, 030024, China 3 Department of Physics, Hangzhou Normal University, Hangzhou 310012, China Corresponding author: e-mail [email protected] Abstract: Electromagnetic absorbers have drawn increasing attention in many areas. A series of plasmonic and metamaterial structures can work as efficient narrow band absorbers due to the excitation of plasmonic or photonic resonances, providing a great potential for applications in designing selective thermal emitters, bio-sensing, etc. In other applications such as solar energy harvesting and photonic detection, the bandwidth of light absorbers is required to be quite broad. Under such a background, a variety of mechanisms of broadband/multiband absorption have been proposed, such as mixing multiple resonances together, exciting phase resonances, slowing down light by anisotropic metamaterials, employing high loss materials and so on. 1. Introduction physical phenomena associated with planar or localized SPPs [13,14]. Electromagnetic (EM) wave absorbers are devices in Metamaterials are artificial assemblies of structured which the incident radiation at the operating wavelengths elements of subwavelength size (i.e., much smaller than can be efficiently absorbed, and then transformed into the wavelength of the incident waves) [15]. They are often ohmic heat or other forms of energy. -
A Metamaterial Frequency-Selective Super-Absorber That Has Absorbing Cross Section Significantly Bigger Than the Geometric Cross Section
A metamaterial frequency-selective super-absorber that has absorbing cross section significantly bigger than the geometric cross section Jack Ng*, Huanyang Chen*,†, and C. T. Chan Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China Abstract Using the idea of transformation optics, we propose a metamaterial device that serves as a frequency-selective super-absorber, which consists of an absorbing core material coated with a shell of isotropic double negative metamaterial. For a fixed volume, the absorption cross section of the super-absorber can be made arbitrarily large at one frequency. The double negative shell serves to amplify the evanescent tail of the high order incident cylindrical waves, which induces strong scattering and absorption. Our conclusion is supported by both analytical Mie theory and numerical finite element simulation. Interesting applications of such a device are discussed. I. Introduction It is possible for a particle to absorb more than the light incident on it. Bohren gave explicit examples in which a small particle can absorb better than a perfect black body of the same size. Examples of such type include a silver particle excited at its surface plasmon resonance and a silicon carbide particle at its surface phonon polariton resonance.1 However, such mechanism is typically limited to very small particles, and for a fixed particle volume, the absorption cross section cannot increase without bound. We shall show in this article that it is possible to design, within the framework of transformation optics,2,3 a device whose absorption efficiency can be arbitrarily large, at least in principle. -
Hyperspectral Imaging for Predicting the Internal Quality of Kiwifruits
www.nature.com/scientificreports OPEN Hyperspectral Imaging for Predicting the Internal Quality of Kiwifruits Based on Variable Received: 18 April 2016 Accepted: 11 July 2017 Selection Algorithms and Published: xx xx xxxx Chemometric Models Hongyan Zhu1, Bingquan Chu1, Yangyang Fan1, Xiaoya Tao2, Wenxin Yin1 & Yong He1 We investigated the feasibility and potentiality of determining frmness, soluble solids content (SSC), and pH in kiwifruits using hyperspectral imaging, combined with variable selection methods and calibration models. The images were acquired by a push-broom hyperspectral refectance imaging system covering two spectral ranges. Weighted regression coefcients (BW), successive projections algorithm (SPA) and genetic algorithm–partial least square (GAPLS) were compared and evaluated for the selection of efective wavelengths. Moreover, multiple linear regression (MLR), partial least squares regression and least squares support vector machine (LS-SVM) were developed to predict quality attributes quantitatively using efective wavelengths. The established models, particularly SPA-MLR, SPA-LS-SVM and GAPLS-LS-SVM, performed well. The SPA-MLR models for frmness (Rpre = 0.9812, RPD = 5.17) and SSC (Rpre = 0.9523, RPD = 3.26) at 380–1023 nm showed excellent performance, whereas GAPLS-LS-SVM was the optimal model at 874–1734 nm for predicting pH (Rpre = 0.9070, RPD = 2.60). Image processing algorithms were developed to transfer the predictive model in every pixel to generate prediction maps that visualize the spatial distribution of frmness and SSC. Hence, the results clearly demonstrated that hyperspectral imaging has the potential as a fast and non-invasive method to predict the quality attributes of kiwifruits. Fruit quality represents a combination of properties and attributes that determine the suitability of the fruit to be eaten as fresh or stored for a reasonable period without deterioration and confer a value regarding consum- er’s satisfaction1, 2. -
Comparison of Hyperspectral Imaging and Near-Infrared Spectroscopy to Determine Nitrogen and Carbon Concentrations in Wheat
remote sensing Article Comparison of Hyperspectral Imaging and Near-Infrared Spectroscopy to Determine Nitrogen and Carbon Concentrations in Wheat Iman Tahmasbian 1,* , Natalie K. Morgan 2, Shahla Hosseini Bai 3, Mark W. Dunlop 1 and Amy F. Moss 2 1 Department of Agriculture and Fisheries, Queensland Government, Toowoomba, QLD 4350, Australia; Scopus affiliation ID: 60028929; [email protected] 2 School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia; [email protected] (N.K.M.); [email protected] (A.F.M.) 3 Centre for Planetary Health and Food Security, School of Environment and Science, Griffith University, Brisbane, QLD 4111, Australia; s.hosseini-bai@griffith.edu.au * Correspondence: [email protected] Abstract: Hyperspectral imaging (HSI) is an emerging rapid and non-destructive technology that has promising application within feed mills and processing plants in poultry and other intensive animal industries. HSI may be advantageous over near infrared spectroscopy (NIRS) as it scans entire samples, which enables compositional gradients and sample heterogenicity to be visualised and analysed. This study was a preliminary investigation to compare the performance of HSI with that of NIRS for quality measurements of ground samples of Australian wheat and to identify the most important spectral regions for predicting carbon (C) and nitrogen (N) concentrations. In total, 69 samples were scanned using an NIRS (400–2500 nm), and two HSI cameras operated in Citation: Tahmasbian, I.; Morgan, 400–1000 nm (VNIR) and 1000–2500 nm (SWIR) spectral regions. Partial least square regression N.K; Hosseini Bai, S.; Dunlop, M.W; (PLSR) models were used to correlate C and N concentrations of 63 calibration samples with their Moss, A.F Comparison of spectral reflectance, with 6 additional samples used for testing the models. -
Hyperspectral Imaging with a TWINS Birefringent Interferometer
Vol. 27, No. 11 | 27 May 2019 | OPTICS EXPRESS 15956 Hyperspectral imaging with a TWINS birefringent interferometer 1,2,4 3,4 3 A. PERRI, B. E. NOGUEIRA DE FARIA, D. C. TELES FERREIRA, D. 1 1 1,2 1,2 3 COMELLI, G. VALENTINI, F. PREDA, D. POLLI, A. M. DE PAULA, G. 1,2 1, CERULLO, AND C. MANZONI * 1IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy 2NIREOS S.R.L., Via G. Durando 39, 20158 Milano, Italy 3Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte-MG, Brazil 4The authors contributed equally to the work *[email protected] Abstract: We introduce a high-performance hyperspectral camera based on the Fourier- transform approach, where the two delayed images are generated by the Translating-Wedge- Based Identical Pulses eNcoding System (TWINS) [Opt. Lett. 37, 3027 (2012)], a common- path birefringent interferometer that combines compactness, intrinsic interferometric delay precision, long-term stability and insensitivity to vibrations. In our imaging system, TWINS is employed as a time-scanning interferometer and generates high-contrast interferograms at the single-pixel level. The camera exhibits high throughput and provides hyperspectral images with spectral background level of −30dB and resolution of 3 THz in the visible spectral range. We show high-quality spectral measurements of absolute reflectance, fluorescence and transmission of artistic objects with various lateral sizes. © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 1. Introduction A great deal of physico-chemical information on objects can be obtained by measuring the spectrum of the light they emit, scatter or reflect. -
Tunable Infrared Metamaterial Emitter for Gas Sensing Application
nanomaterials Article Tunable Infrared Metamaterial Emitter for Gas Sensing Application Ruijia Xu and Yu-Sheng Lin * State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China; [email protected] * Correspondence: [email protected] Received: 17 June 2020; Accepted: 22 July 2020; Published: 24 July 2020 Abstract: We present an on-chip tunable infrared (IR) metamaterial emitter for gas sensing applications. The proposed emitter exhibits high electrical-thermal-optical efficiency, which can be realized by the integration of microelectromechanical system (MEMS) microheaters and IR metamaterials. According to the blackbody radiation law, high-efficiency IR radiation can be generated by driving a Direct Current (DC) bias voltage on a microheater. The MEMS microheater has a Peano-shaped microstructure, which exhibits great heating uniformity and high energy conversion efficiency. The implantation of a top metamaterial layer can narrow the bandwidth of the radiation spectrum from the microheater to perform wavelength-selective and narrow-band IR emission. A linear relationship between emission wavelengths and deformation ratios provides an effective approach to meet the requirement at different IR wavelengths by tailoring the suitable metamaterial pattern. The maximum radiated power of the proposed IR emitter is 85.0 µW. Furthermore, a tunable emission is achieved at a wavelength around 2.44 µm with a full-width at half-maximum of 0.38 µm, which is suitable for high-sensitivity gas sensing applications. This work provides a strategy for electro-thermal-optical devices to be used as sensors, emitters, and switches in the IR wavelength range. -
Hyperspectral Microscopy for Early and Rapid Detection Of
HYPERSPECTRAL MICROSCOPY FOR EARLY AND RAPID DETECTION OF SALMONELLA SEROTYPES by MATTHEW BRENT EADY (Under the Direction of Bosoon Park) ABSTRACT Optical microbial detection methodologies have shown the potential as early and rapid pathogen detection methods. This proof-of-concept project explores the use of hyperspectral microscopy as a potential method for early and rapid classification of five Salmonella serotypes. Darkfield hyperspectral microscope images were collected at early incubation times of 6, 8, 10, and 12 hrs., then compared to 24 hrs. incubation. Hypercube data collected from cells were analyzed through multivariate data analysis (MVDA) methods to assess classification ability of early incubation times. A separate experiment was conducted to explore the ability of analyzing hyperspectral data collected from only informative spectral bands as opposed to the original 89 spectral bands. MVDA showed that incubation times as early as 8 hours had near identical spectra and classification abilities compared to 24 hours; while the original 89-point spectrum could be reduced to 3 selected spectral bands and maintain high serotype classification accuracy. INDEX WORDS: Salmonella, hyperspectral microscopy, early detection, rapid detection, multivariate data HYPERSPECTRAL MICROSCOPY FOR EARLY AND RAPID DETECTION OF SALMONELLA SEROTYPES by MATTHEW BRENT EADY BSA, The University of Georgia, 2011 A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree MASTER OF -
Conceptual-Based Design of an Ultrabroadband Microwave Metamaterial Absorber
Conceptual-based design of an ultrabroadband microwave metamaterial absorber Sichao Qua,1, Yuxiao Houa,1, and Ping Shenga,2 aDepartment of Physics, Hong Kong University of Science and Technology, Hong Kong, China Edited by David A. Weitz, Harvard University, Cambridge, MA, and approved August 4, 2021 (received for review June 07, 2021) By introducing metallic ring structural dipole resonances in the micro- In this work, the basic building block in our design is just a wave regime, we have designed and realized a metamaterial absorber metallic ring that is fabricated by the printed circuit board (PCB) with hierarchical structures that can display an averaged −19.4 dB technology. The final integrated sample can exhibit near-perfect reflection loss (∼99% absorption) from 3 to 40 GHz. The measured absorption from 3 to 40 GHz, covering the whole high-frequency performance is independent of the polarizations of the incident wave 5G bands (32). Another crucial measure of an absorber is its thick- at normal incidence, while absorption at oblique incidence remains ness. While a thick enough absorber can absorb everything over considerably effective up to 45°. We provide a conceptual basis for all frequency regimes, it is nevertheless impractical in terms of our absorber design based on the capacitive-coupled electrical di- applications. For a passive absorber, there is a common standard pole resonances in the lateral plane, coupled to the standing wave set by the causality-dictated minimum sample thickness that is along the incident wave direction. To realize broadband imped- associated with any given reflection spectrum (33). In our case, ance matching, resistive dissipation of the metallic ring is optimally the overall thickness of the absorber is 14.2 mm, only 5% over tuned by using the approach of dispersion engineering. -
Integrated Raman and Hyperspectral Microscopy
ELEMENTAL ANALYSIS FLUORESCENCE Integrated Raman and GRATINGS & OEM SPECTROMETERS OPTICAL COMPONENTS Hyperspectral Microscopy FORENSICS PARTICLE CHARACTERIZATION RAMAN Combined spectral imaging technologies SPECTROSCOPIC ELLIPSOMETRY SPR IMAGING XploRA® PLUS integrates hyperspectral microscopy with confocal Raman microscopy for multimodal hyperspectral imaging on a single platform HORIBA Scientific is happy to announce the integration photoluminescence, transmittance and reflectance) of the enhanced darkfield (EDF) and optical hyperspectral modes. Switching between imaging modes requires no imaging (HSI) technologies from CytoViva® with HORIBA’s sample movement whatsoever, ensuring all of these multi- renowned confocal Raman microscopy, XploRA PLUS. modal images are truly of the same area. The integrated system offers versatile modes of imaging and hyperspectral imaging that are very important for XploRA PLUS houses four gratings for optimized spectral nanomaterial and life science studies. resolution, and up to three lasers (select from blue to NIR+) for performing Raman, PL and/or FL hyperspectral This integrated microscope platform provides both imaging. EMCCD (electron multiplying CCD) is available widefield imaging (reflection, transmission, brightfield, for enhanced sensitivity as an upgrade from the CCD as darkfield, polarized light and epi-fluorescence), a detector. Operations, including switching lasers and and hyperspectral imaging (Raman, fluorescence, gratings, are fully automated via LabSpec 6 Spectroscopy Suite. LabSpec -
Section1: Introduction to Hyperspectral Imaging
Section1: Introduction to Hyperspectral imaging The information provided here is a short overview of NIR spectroscopy and hyperspectral imaging for a novice to this field. Please consult literature in the Reference section for more informative explanation and further reading. What is NIR hyperspectral imaging? Hyperspectral imaging is a combination of imaging and spectroscopy. What does spectroscopy entail? Spectroscopy studies the interaction between matter and electromagnetic radiation and records the amount of radiation absorbed or emitted as a spectrum over a specific wavelength range. What is electromagnetic radiation? In physics, electromagnetic radiation is defined as the waves of the electromagnetic field. The waves propagates through space and time and carries electromagnetic energy. Waves are characterized by their frequency of oscillation (number of times that a wave passes by a certain point per unit time) or by the wavelength (units expressed as nm or cm-1 for wavenumber). Waves of different frequencies make up the electromagnetic spectrum. Figure 1: An electromagnetic wave can be defined by the length from one point to the identical point on the next wave and is indicated as wavelength (nm) or wavenumber (cm-1). What is the electromagnetic spectrum? The electromagnetic spectrum covers the range of frequencies from the wavelengths with shorter frequencies linked to nuclear radiation (Gamma rays), which carries high energy, followed by X-rays, ultraviolet (UV)-, visible-, infrared (IR) to the radio waves, which carry low energy (Fig 2). Figure 2: Schematic for the electromagnetic spectrum. Gamma rays have short wavelengths and this increase in the direction of the Radio waves. As wavelengths decrease the energy levels increase. -
1 Narrowband Metamaterial Absorber for Terahertz Secure Labeling
Narrowband Metamaterial Absorber for Terahertz Secure Labeling Magued Nasr *a, Jonathan T. Richard *d, Scott A. Skirlo *b, Martin S. Heimbeck c, John D. Joannopoulos,b Marin Soljacic b, Henry O. Everitt c†, Lawrence Domash a * Equal contributors a Triton Systems Inc., 200 Turnpike Rd #2, Chelmsford, MA 01824 b Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 c U.S. Army Aviation and Missile RD&E Center, Redstone Arsenal, AL 35898 d IERUS Technologies, 2904 Westcorp Blvd Suite 210, Huntsville, AL 35805 † Corresponding author: [email protected] Abstract Flexible metamaterial films, fabricated by photolithography on a thin copper-backed polyimide substrate, are used to mark or barcode objects securely. The films are characterized by continuous wave terahertz spectroscopic ellipsometry and visualized by a scanning confocal imager coupled to a vector network analyzer that constructed a terahertz spectral hypercube. These films exhibit a strong, narrowband, polarization- and angle-insensitive absorption at wavelengths near one millimeter. Consequently, the films are nearly indistinguishable at visible or infrared wavelengths and may be easily observed by terahertz imaging only at the resonance frequency of the film. 1 Introduction Terahertz radiation in the long wavelength 1 - 3 mm band penetrates dry dielectrics such as plastics, concrete, and fabric while being strongly absorbed by water and water vapor. This combination of characteristics may be exploited for numerous applications including short-range communications and radar, collision avoidance radar, non-destructive testing of materials and structures, security imaging, medical diagnosis, and spectroscopy.[1,2,3] Materials with interesting terahertz properties also play a role in numerous security applications due to their limited range and high bandwidth.