ECEG105/ECEU646 Optics for Engine6ers Course Notes Part 1: Introduction

Transcription

1 ECEG105/ECEU646 Optics for Engine6ers Course Notes Part 1: Introduction Prof. Charles A. DiMarzio Northeastern University Fall 2008 Sep a-1

2 Lecture 1 Overview Administrivia Course Layout Grading Syllabus Introduction Why Optics? A bit of history Our Approach a-2

3 Why Optics? Absorption Spectrum of the Atmosphere Index of Refraction from Jackson 1nm 1µm 1mm 1m 1km Absorption Spectrum of Liquid Water Sep km 1m 1mm1µm1nm a-3

4 Earthlight a-4

5 A Bit of History...and the foot of it of brass, of the lookingglasses of the women assembling, (Exodus 38:8) Rectilinear Propagation (Euclid) Shortest Path (Almost Right!) (Hero of Alexandria) Light as Pressure Wave (Descartes) 0 Transverse Wave, Polarization Interference (Young) Law of Least Time (Fermat) Light & Magnetism (Faraday) v<c, & Two Kinds of Light (Huygens) Plane of Incidence Curved Mirrors (Al Hazen) Wave Theory (Longitudinal) (Fresnel) Empirical Law of Refraction (Snell) Corpuscles, Ether (Newton) EM Theory (Maxwell) Rejectionof Ether, Early QM (Poincare, Einstein) a-5 Sep

6 More Recent History Polaroid Sheets (Land) Optical Fiber (Lamm) Quantum Mechanics Phase Contrast (Zernicke) Laser (Maiman) SM Fiber (Hicks) Optical Maser (Schalow, Townes) Speed/Light (Michaelson) Spont. Emission (Einstein) Sep 2008 Holography (Gabor) Hubble Telescope HeNe (Javan) GaAs (4 Groups) CO2 (Patel) Many New Lasers Erbium Fiber Amp FEL (Madey) Commerci al Fiber Link (Chicago) a-6

7 The First Laser?? News Photo of the First Laser Malibu, 1960 The First Laser Jan 2005 "Laser, inter eximia naturae dona numeratum plurimis compositionibus inseritur*" "The laser is numbered among the most miraculous gifts of nature and lends itself to a variety of applications." Pliny, Natural History XXII, a-7

8 Some Everyday Applications Illumination Signaling Cameras; Film and Electronic Bar-Code Reader Surveying and Rangefinding Microscopy Astronomy a-8

9 My Research Interests Biological and Medical Imaging Multi-Modal Microscopy Acousto-Photonic Imaging (DOT and Ultrasound) Optical Quadrature Microscopy Landmine Detection Laser-Induced Acoustic Mine Detection Microwave-Enhanced Infrared Thermography Environmental Sensing Optical Magnetic Field Sensor Underwater Imaging with a Laser Line Scanner Hyperspectral Imaging Laboratory Experiments Jul a-9

10 Some Other Applications (1) Communication Lasers and Fast Modulation Fibers for Propagation Fast Detectors Dense Wavelength Diversity Multiplexing Free-Space Propagation (Not Much) Optical Disk Memory Lasers, Detectors Diffraction Limited Optics a-10

11 Some Other Applications (2) Photo Lithography for Integrated Circuits Short Wavelength Sources Diffraction Limited Optics Adaptive Optical Imaging Non-Linear Materials or Mechanical Actuators Velocimetry and Vibrometry Coherent Detection, Coherent Sources a-11

12 Some Other Applications (3) Hyperspectral Imaging Dispersive Elements Large Detector Arrays Fast Processing Medical Treatment Delivery Dosimetry a-12

13 Some Recent Advances Laser Tweezers Optical Cooling Squeezed States Entangled-States Fiber-Based Sensors Optical Micro-Electro-Mechanical Systems a-13

14 Some Everyday Concepts (1) Specular and Diffuse Reflection Refraction and Transmission Specular Dec 2004 Diffuse Retro a-14

15 Example Interactions Slab Transmission Slab Absorption and Scattering Mostly Diffuse Reflection Dec 2004 Specular with some Diffuse Chuck DiMarzio, Northeastern University a-15 Reflection

16 Some Everyday Concepts (2) Imaging Object Image Wavefronts Sep 2007 Object Image Rays The Observer The Observer a-16

17 Imaging Near Card Demonstrates Camera is Focused Closer than Lens July Jul 2007 Sep a-17

18 High-School Optics F Object Image F a-18 Stopped Here 4 Jan 05

19 Our Approach Maxwell s Equations Wave Equation Scalar Wave Equation Geometric Optics Polarization Interference Diffraction Radiometry a-19 stopped 12 Sep

20 Maxwell s Equations Jul a-20

21 Maxwell s Equations Source-Free Region No ρ or J Isotropic Medium E Parallel to D Harmonic Functions No Nonlinear Effects a-21

22 Getting to the Wave Equation E D Almost everything interesting is here H B a-22

23 The Goodies are in Epsilon D E D E H B H B More on this later in the course a-23

24 The General Problem Goals Solve Maxwell s Equations Satisfy Boundary Conditions Approaches Special Cases (eg. Plane, Spherical, etc.) Approximations Circuit Theory (λ >>D) Wave Theory (λ D) Geometric Optics (λ <<D) a-24

25 Steps to Geometric Optics Maxwell s Equations Vector Wave Equation Scalar Wave Equation General Wave Solution Eikonel Equation (zero-wavelength approximation) a-25

26 Vector Wave Equation D E H 3 Jan 2005 Sep 2007 B a-26

27 Scalar Wave Equation D E H 3 Linear, Isotropic Medium B (Two States of Polarization) Sep a-27

28 Eikonel Equation (1) a-28

29 Eikonel Equation (2) 4π... 2π a-29

30 Eikonel Equation (3) L(r)=Constant Defines Wavefronts Thus, Wavefronts Are Perpendicular to Rays ΔL= ni ℓi Define Optical Path Length Compare Travel Time to Light in Vacuum n1 n2 n3 n4 n a-30

31 Plane Waves Scalar Wave Equation General Solution Plane-Wave Solution Plane-Wave in z Direction Dec 2004 E=E0 e E=E0 e i n k r ωt i nkz ωt a-31

32 Optical Path Concept Not to Be Confused with Image Location Image Distance Physical Distance OPL a-32

33 Fermat s Principle Where Does Ray Go? Minimize Optical Path Imaging: Many Minimal Paths a-33

34 Jan a-34

35 Dec a-35 Stopped Here Thu 6 Jan 05