Optical Properties of Paper: Theory and Practice
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Lecture 5. Interstellar Dust: Optical Properties
Lecture 5. Interstellar Dust: Optical Properties 1. Introduction 2. Extinction 3. Mie Scattering 4. Dust to Gas Ratio 5. Appendices References Spitzer Ch. 7, Osterbrock Ch. 7 DC Whittet, Dust in the Galactic Environment (IoP, 2002) E Krugel, Physics of Interstellar Dust (IoP, 2003) B Draine, ARAA, 41, 241, 2003 1. Introduction: Brief History of Dust Nebular gas long accepted but existence of absorbing interstellar dust controversial. Herschel (1738-1822) found few stars in some directions, later extensively demonstrated by Barnard’s photos of dark clouds. Trumpler (PASP 42 214 1930) conclusively demonstrated interstellar absorption by comparing luminosity distances & angular diameter distances for open clusters: • Angular diameter distances are systematically smaller • Discrepancy grows with distance • Distant clusters are redder • Estimated ~ 2 mag/kpc absorption • Attributed it to Rayleigh scattering by gas Some of the Evidence for Interstellar Dust Extinction (reddening of bright stars, dark clouds) Polarization of starlight Scattering (reflection nebulae) Continuum IR emission Depletion of refractory elements from the gas Dust is also observed in the winds of AGB stars, SNRs, young stellar objects (YSOs), comets, interplanetary Dust particles (IDPs), and in external galaxies. The extinction varies continuously with wavelength and requires macroscopic absorbers (or “dust” particles). Examples of the Effects of Dust Extinction B68 Scattering - Pleiades Extinction: Some Definitions Optical depth, cross section, & efficiency: ext ext ext τ λ = ∫ ndustσ λ ds = σ λ ∫ ndust 2 = πa Qext (λ) Ndust nd is the volumetric dust density The magnitude of the extinction Aλ : ext I(λ) = I0 (λ) exp[−τ λ ] Aλ =−2.5log10 []I(λ)/I0(λ) ext ext = 2.5log10(e)τ λ =1.086τ λ 2. -
Chapter 4 Reflected Light Optics
l CHAPTER 4 REFLECTED LIGHT OPTICS 4.1 INTRODUCTION Light is a form ofelectromagnetic radiation. which may be emitted by matter that is in a suitably "energized" (excited) state (e.g.,the tungsten filament ofa microscope lamp emits light when "energized" by the passage of an electric current). One ofthe interesting consequences ofthe developments in physics in the early part of the twentieth century was the realization that light and other forms of electromagnetic radiation can be described both as waves and as a stream ofparticles (photons). These are not conflicting theories but rather complementary ways of describing light; in different circumstances. either one may be the more appropriate. For most aspects ofmicroscope optics. the "classical" approach ofdescribing light as waves is more applicable. However, particularly (as outlined in Chapter 5) when the relationship between the reflecting process and the structure and composition ofa solid is considered. it is useful to regard light as photons. The electromagnetic radiation detected by the human eye is actually only a very small part of the complete electromagnetic spectrum, which can be re garded as a continuum from the very low energies and long wavelengths characteristic ofradio waves to the very high energies (and shortwavelengths) of gamma rays and cosmic rays. As shown in Figure 4.1, the more familiar regions ofthe infrared, visible light, ultraviolet. and X-rays fall between these extremes of energy and wavelength. Points in the electromagnetic spectrum can be specified using a variety ofenergy or wavelength units. The most com mon energy unit employed by physicists is the electron volt' (eV). -
Essay on Optics
Essay on Optics by Émilie du Châtelet translated, with notes, by Bryce Gessell published by LICENSE AND CITATION INFORMATION 2019 © Bryce Gessell This work is licensed by the copyright holder under a Creative Commons Attribution-NonCommercial 4.0 International License. Published by Project Vox http://projectvox.org How to cite this text: Du Châtelet, Emilie. Essay on Optics. Translated by Bryce Gessell. Project Vox. Durham, NC: Duke University Libraries, 2019. http://projectvox.org/du-chatelet-1706-1749/texts/essay-on-optics This translation is based on the copy of Du Châtelet’s Essai sur l’Optique located in the Universitätsbibliothek Basel (L I a 755, fo. 230–265). The original essay was transcribed and edited in 2017 by Bryce Gessell, Fritz Nagel, and Andrew Janiak, and published on Project Vox (http://projectvox.org/du-chatelet-1706-1749/texts/essai-sur-loptique). 2 This work is governed by a CC BY-NC 4.0 license. You may share or adapt the work if you give credit, link to the license, and indicate changes. You may not use the work for commercial purposes. See creativecommons.org for details. CONTENTS License and Citation Information 2 Editor’s Introduction to the Essay and the Translation 4 Essay on Optics Introduction 7 Essay on Optics Chapter 1: On Light 8 Essay on Optics Chapter 2: On Transparent Bodies, and on the Causes of Transparence 11 Essay on Optics Chapter 3: On Opacity, and on Opaque Bodies 28 Essay on Optics Chapter 4: On the Formation of Colors 37 Appendix 1: Figures for Essay on Optics 53 Appendix 2: Daniel II Bernoulli’s Note 55 Appendix 3: Figures from Musschenbroek’s Elementa Physicae (1734) 56 Appendix 4: Figures from Newton’s Principia Mathematica (1726) 59 3 This work is governed by a CC BY-NC 4.0 license. -
Optical Properties of Tio2 Based Multilayer Thin Films: Application to Optical Filters
Int. J. Thin Fil. Sci. Tec. 4, No. 1, 17-21 (2015) 17 International Journal of Thin Films Science and Technology http://dx.doi.org/10.12785/ijtfst/040104 Optical Properties of TiO2 Based Multilayer Thin Films: Application to Optical Filters. M. Kitui1, M. M Mwamburi2, F. Gaitho1, C. M. Maghanga3,*. 1Department of Physics, Masinde Muliro University of Science and Technology, P.O. Box 190, 50100, Kakamega, Kenya. 2Department of Physics, University of Eldoret, P.O. Box 1125 Eldoret, Kenya. 3Department of computer and Mathematics, Kabarak University, P.O. Private Bag Kabarak, Kenya. Received: 6 Jul. 2014, Revised: 13 Oct. 2014, Accepted: 19 Oct. 2014. Published online: 1 Jan. 2015. Abstract: Optical filters have received much attention currently due to the increasing demand in various applications. Spectral filters block specific wavelengths or ranges of wavelengths and transmit the rest of the spectrum. This paper reports on the simulated TiO2 – SiO2 optical filters. The design utilizes a high refractive index TiO2 thin films which were fabricated using spray Pyrolysis technique and low refractive index SiO2 obtained theoretically. The refractive index and extinction coefficient of the fabricated TiO2 thin films were extracted by simulation based on the best fit. This data was then used to design a five alternating layer stack which resulted into band pass with notch filters. The number of band passes and notches increase with the increase of individual layer thickness in the stack. Keywords: Multilayer, Optical filter, TiO2 and SiO2, modeling. 1. Introduction successive boundaries of different layers of the stack. The interface formed between the alternating layers has a great influence on the performance of the multilayer devices [4]. -
Opacities: Means & Uncertainties
OPACITIES: MEANS & Previously... UNCERTAINTIES Christopher Fontes Computational Physics Division Los Alamos National Laboratory ICTP-IAEA Advanced School and Workshop on Modern Methods in Plasma Spectroscopy Trieste, March 16-27, 2015 Operated by the Los Alamos National Security, LLC for the DOE/NNSA Slide 1 Before moving on to the topic of mean opacities, let’s look at Al opacities at different temperatures 19 -3 • Our main example is kT = 40 eV and Ne = 10 cm with <Z> = 10.05 (Li-like ions are dominant) • Consider raising and lowering the temperature: – kT = 400 eV (<Z> = 13.0; fully ionized) – kT = 20 eV (<Z> = 6.1; nitrogen-like stage is dominant) Slide 2 Slide 3 Slide 4 Slide 5 Slide 6 Slide 7 Road map to mean opacities Mean (gray) opacities In order of most to least refined • Under certain conditions, the need to transport a with respect to frequency resolution: frequency-dependent radiation intensity, Iν, can be relaxed in favor of an integrated intensity, I, given by ∞ κν (monochromatic) I = I dν ∫0 ν • Applying this notion of integrated quantities to each term of the radiation transport equation results in a new set of MG κ (multigroup) equations, similar to the original, frequency-dependent formulations • Frequency-dependent absorption terms that formerly (gray) contained will instead contain a suitably averaged κ κν “mean opacity” or “gray opacity” denoted by κ Slide 8 Slide 9 Mean opacities (continued) Types of mean opacities • The mean opacity κ represents, in a single number, the • Two most common types of gray opacities -
Optical Properties of Materials JJL Morton
Electrical and optical properties of materials JJL Morton Electrical and optical properties of materials John JL Morton Part 5: Optical properties of materials 5.1 Reflection and transmission of light 5.1.1 Normal to the interface E z=0 z E E H A H C B H Material 1 Material 2 Figure 5.1: Reflection and transmission normal to the interface We shall now examine the properties of reflected and transmitted elec- tromagnetic waves. Let's begin by considering the case of reflection and transmission where the incident wave is normal to the interface, as shown in Figure 5.1. We have been using E = E0 exp[i(kz − !t)] to describe waves, where the speed of the wave (a function of the material) is !=k. In order to express the wave in terms which are explicitly a function of the material in which it is propagating, we can write the wavenumber k as: ! !n k = = = nk0 (5.1) c c0 where n is the refractive index of the material and k0 is the wavenumber of the wave, were it to be travelling in free space. We will therefore write a wave as the following (with z replaced with whatever direction the wave is travelling in): Ex = E0 exp [i (nk0z − !t)] (5.2) In this problem there are three waves we must consider: the incident wave A, the reflected wave B and the transmitted wave C. We'll write down the equations for each of these waves, using the impedance Z = Ex=Hy, and noting the flip in the direction of H upon reflection (see Figure 5.1), and the different refractive indices and impedances for the different materials. -
Radio Astronomy
Edition of 2013 HANDBOOK ON RADIO ASTRONOMY International Telecommunication Union Sales and Marketing Division Place des Nations *38650* CH-1211 Geneva 20 Switzerland Fax: +41 22 730 5194 Printed in Switzerland Tel.: +41 22 730 6141 Geneva, 2013 E-mail: [email protected] ISBN: 978-92-61-14481-4 Edition of 2013 Web: www.itu.int/publications Photo credit: ATCA David Smyth HANDBOOK ON RADIO ASTRONOMY Radiocommunication Bureau Handbook on Radio Astronomy Third Edition EDITION OF 2013 RADIOCOMMUNICATION BUREAU Cover photo: Six identical 22-m antennas make up CSIRO's Australia Telescope Compact Array, an earth-rotation synthesis telescope located at the Paul Wild Observatory. Credit: David Smyth. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. - iii - Introduction to the third edition by the Chairman of ITU-R Working Party 7D (Radio Astronomy) It is an honour and privilege to present the third edition of the Handbook – Radio Astronomy, and I do so with great pleasure. The Handbook is not intended as a source book on radio astronomy, but is concerned principally with those aspects of radio astronomy that are relevant to frequency coordination, that is, the management of radio spectrum usage in order to minimize interference between radiocommunication services. Radio astronomy does not involve the transmission of radiowaves in the frequency bands allocated for its operation, and cannot cause harmful interference to other services. On the other hand, the received cosmic signals are usually extremely weak, and transmissions of other services can interfere with such signals. -
Chapter 19/ Optical Properties
Chapter 19 /Optical Properties The four notched and transpar- ent rods shown in this photograph demonstrate the phenomenon of photoelasticity. When elastically deformed, the optical properties (e.g., index of refraction) of a photoelastic specimen become anisotropic. Using a special optical system and polarized light, the stress distribution within the speci- men may be deduced from inter- ference fringes that are produced. These fringes within the four photoelastic specimens shown in the photograph indicate how the stress concentration and distribu- tion change with notch geometry for an axial tensile stress. (Photo- graph courtesy of Measurements Group, Inc., Raleigh, North Carolina.) Why Study the Optical Properties of Materials? When materials are exposed to electromagnetic radia- materials, we note that the performance of optical tion, it is sometimes important to be able to predict fibers is increased by introducing a gradual variation and alter their responses. This is possible when we are of the index of refraction (i.e., a graded index) at the familiar with their optical properties, and understand outer surface of the fiber. This is accomplished by the mechanisms responsible for their optical behaviors. the addition of specific impurities in controlled For example, in Section 19.14 on optical fiber concentrations. 766 Learning Objectives After careful study of this chapter you should be able to do the following: 1. Compute the energy of a photon given its fre- 5. Describe the mechanism of photon absorption quency and the value of Planck’s constant. for (a) high-purity insulators and semiconduc- 2. Briefly describe electronic polarization that re- tors, and (b) insulators and semiconductors that sults from electromagnetic radiation-atomic in- contain electrically active defects. -
Investigation of Dichroism by Spectrophotometric Methods
Application Note Glass, Ceramics and Optics Investigation of Dichroism by Spectrophotometric Methods Authors Introduction N.S. Kozlova, E.V. Zabelina, Pleochroism (from ancient greek πλέον «more» + χρόμα «color») is an optical I.S. Didenko, A.P. Kozlova, phenomenon when a transparent crystal will have different colors if it is viewed from Zh.A. Goreeva, T different angles (1). Sometimes the color change is limited to shade changes such NUST “MISiS”, Russia as from pale pink to dark pink (2). Crystals are divided into optically isotropic (cubic crystal system), optically anisotropic uniaxial (hexagonal, trigonal, tetragonal crystal systems) and optically anisotropic biaxial (orthorhombic, monoclinic, triclinic crystal systems). The greatest change is limited to three colors. It may be observed in biaxial crystals and is called trichroic. A two color change may be observed in uniaxial crystals and called dichroic. Pleochroic is often the term used to cover both (2). Pleochroism is caused by optical anisotropy of the crystals Dichroism can be observed in non-polarized light but in (1-3). The absorption of light in the optically anisotropic polarized light it may be more pronounced if the plane of crystals depends on the frequency of the light wave and its polarization of incident light matches plane of polarization of polarization (direction of the electric vector in it) (3, 4). light that propagates in the crystal—ordinary or extraordinary Generally, any ray of light in the optical anisotropic crystal is wave. divided into two rays with perpendicular polarizations and The difference in absorbance of ray lights may be minor, but different velocities (v1, v2) which are inversely proportional to it may be significant and should be considered both when the refractive indices (n1, n2) (4). -
Light Scattering by Fractal Dust Aggregates. II. Opacity and Asymmetry Parameter
The Astrophysical Journal, 860:79 (17pp), 2018 June 10 https://doi.org/10.3847/1538-4357/aac32d © 2018. The American Astronomical Society. All rights reserved. Light Scattering by Fractal Dust Aggregates. II. Opacity and Asymmetry Parameter Ryo Tazaki and Hidekazu Tanaka Astronomical Institute, Graduate School of Science Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai 980-8578, Japan; [email protected] Received 2018 March 9; revised 2018 April 26; accepted 2018 May 6; published 2018 June 14 Abstract Optical properties of dust aggregates are important at various astrophysical environments. To find a reliable approximation method for optical properties of dust aggregates, we calculate the opacity and the asymmetry parameter of dust aggregates by using a rigorous numerical method, the T-Matrix Method, and then the results are compared to those obtained by approximate methods: the Rayleigh–Gans–Debye (RGD) theory, the effective medium theory (EMT), and the distribution of hollow spheres method (DHS). First of all, we confirm that the RGD theory breaks down when multiple scattering is important. In addition, we find that both EMT and DHS fail to reproduce the optical properties of dust aggregates with fractal dimensions of 2 when the incident wavelength is shorter than the aggregate radius. In order to solve these problems, we test the mean field theory (MFT), where multiple scattering can be taken into account. We show that the extinction opacity of dust aggregates can be well reproduced by MFT. However, it is also shown that MFT is not able to reproduce the scattering and absorption opacities when multiple scattering is important. -
The Optical Effective Attenuation Coefficient As an Informative
hv photonics Article The Optical Effective Attenuation Coefficient as an Informative Measure of Brain Health in Aging Antonio M. Chiarelli 1,2,* , Kathy A. Low 1, Edward L. Maclin 1, Mark A. Fletcher 1, Tania S. Kong 1,3, Benjamin Zimmerman 1, Chin Hong Tan 1,4,5 , Bradley P. Sutton 1,6, Monica Fabiani 1,3,* and Gabriele Gratton 1,3,* 1 Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 2 Department of Neuroscience, Imaging and Clinical Sciences, University G. D’Annunzio of Chieti-Pescara, 66100 Chieti, Italy 3 Psychology Department, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA 4 Division of Psychology, Nanyang Technological University, Singapore 639818, Singapore 5 Department of Pharmacology, National University of Singapore, Singapore 117600, Singapore 6 Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA * Correspondence: [email protected] (A.M.C.); [email protected] (M.F.); [email protected] (G.G.) Received: 24 May 2019; Accepted: 10 July 2019; Published: 12 July 2019 Abstract: Aging is accompanied by widespread changes in brain tissue. Here, we hypothesized that head tissue opacity to near-infrared light provides information about the health status of the brain’s cortical mantle. In diffusive media such as the head, opacity is quantified through the Effective Attenuation Coefficient (EAC), which is proportional to the geometric mean of the absorption and reduced scattering coefficients. EAC is estimated by the slope of the relationship between source–detector distance and the logarithm of the amount of light reaching the detector (optical density). -
7.1 Optical Constants and Light Transmittance
7 . Optical Properties 7・ 1 Optical Constants and Light Transmittance The refractive index of Iupilon / NOVAREX at normal temperature is nD 25℃ = 1,585 The temperature characteristic is as shown in Fig. 4・1・1‐1. The refractive index of other resins was shown in Table 7・1‐1. Table 7・1‐1 Refractive index of various plastics Polymers nD 25 Polymers nD 25 Polymers nD 25 Polymethyl・methacrylate1.490‐1.500 Polystyrene 1.590‐1.600 (PMMA) 1.570 PETP 1.655 Polymethylstyrene 1.560‐1.580 Acrylonitrile・ 66 Nylon 1.530 Polyvinyl acetate 1.450‐1.470 Styrene(AS Polyacetal 1.480 Polytetrafluoroethylene 1.350 Polutrifluoro Polyvinyl chloride 1.540 1.430 Phenoxy resin 1.598 ethylene monochloride Polyvinylidene chloride 1.600‐1.630 1.510 Polysulphone 1.633 Low density polyethylene High density Cellulose acetate 1.490‐1.500 1.540 SBR 1.520‐1.550 polyethylene Propionic acid 1.460‐1.490 Polypropylene 1.490 TPX 1.465 Cellulose 1.460‐1.510 Polybutyrene 1.500 Epoxy resin 1.550‐1.610 Nitrocellulose The relation between light transmittance and thickness of Iupilon / NOVAREX is shown in Fig. 7・1‐1. The wavelength characteristic is shown in Fig. 7・1‐2. The light transmittance wavelength characteristics of polycarbonate and other transparent materials are shown in Fig. 7・1‐3. light transmittance light (%) transmi- ttance (%) thickness (mm) wavelength (nm) Fig. 7・1‐1 Relation between light Fig. 7・1‐2 Light transmittance of Iupilon / transmittancee and thickness of Iupilon / NOVAREX NOVAREX glass 5.72mm injection molding PMMA 3.43mm compression molding light 3.25mm transmittance injection molding (%) PC 3.43mm wavelength (nm) Fig.