Trivia Question In class this week, we will be talking about anisotropic medium. One example or anisotropic medium are crystals. One example of a crystal structure is diamond. What is the LARGEST diamond (uncut) in the world? (WIKIPEDIA) (1 carat diamond is 200 mg. 100 carats=0.044 lbs) 112 carats 195 carats 599 carats 970 carats 3106 carats

Trivia Question In class this week, we will be talking about anisotropic medium. One example or anisotropic medium are crystals. One example of a crystal structure is diamond. What is the LARGEST diamond (uncut) in the world? (WIKIPEDIA) (1 carat diamond is 200 mg. 100 carats=0.044 lbs) 112 carats - Hope Diamond (US Museum of Natural History) 195 carats - Pink Panther (Fictional from Pink Panther Movies. Darya-ye Noor is largest pink diamond (Iran) 599 carats - Centenary Diamond 970 carats - Excelsior Diamond 3106 carats - Cullinan Diamond - Discovered in 1905, the Cullinan is, at 3106.75 carats (621.35 g), the largest rough gem- quality diamond ever found. It was cut into 105 diamonds including the Cullinan I or the Great Star of Africa

Wood – Anistropic Material Wood comes from trees…. Growth of wood includes ‘rings’ or ‘grain of wood’. The grain of wood gives wood mechanical strength. Easier to break ALONG grain Hard to break ACROSS gain

Wood – Anistropic Material mg Which orientation of the grain in the wood will support more weight? mg

Langer’s Lines Langer's lines, also called cleavage lines, is a term used to define the direction within the human skin along which the skin has the least flexibility. These lines correspond to the alignment of collagen fibers within the dermis. (http://www.med-ars.it/galleries/langer.htm)

Anisotropic Media Remember, even a gas is anisotropic over a small enough spatial scale, so you need to compare the WAVELENGTH of the light to the SPATIAL SCALE of the anisotropy to determine if the material is indeed anisotropic to light.

Susceptibility Tensor Fundamentally, the directionally dependent Susceptibility arises from different ‘spring constants’ in different directions.

Principle Axes of Common Crystals Diamond Cubic Structure

Snell’s Law in Uniaxial Crystal no ne E fields oriented parallel to z direction experience refractive index ne. E Fields oriented PERPENDICULAR to z direction experience refractive index no. E Field oriented partially along z direction and partially perpendicular experience BOTH refractive indices.

Ordinary and Extra-O waves

Phase Change in Uniaxial Crystals Optical axis PARALLEL to surface in plane of page. EiP ne k no EiS L

Trivia Question We have all seen ‘one way’ mirrors in use on TV police shows, in which of the following are one way mirrors NOT used? (a) The “Haunted Mansion” attraction at Walt Disney World (b) In Reality TV shows (c) Marketing research (d) Interrogation rooms (e) Security Observation rooms

Trivia Question All of them!! We have all seen ‘one way’ mirrors in use on TV police shows, in which of the following are one way mirrors NOT used? (a) The “Haunted Mansion” attraction at Walt Disney World (b) In Reality TV shows (c) Marketing research (d) Interrogation rooms (e) Security Observation rooms All of them!!

How do ‘one way’ mirrors work? The cheap version (and most often used), makes use of a BRIGHT ‘interrogation’ room and a darkened ‘observation’ room. Between the two is a partially reflecting mirror (~50%). Bright room occupants see their own reflection from mirror. Dark room occupants see light from lighted room through partially reflecting mirror More expensive method: Mirror fabricated as ‘optical diode’ or ‘optical isolator’. We will return to this concept later….

Animations of Electromagnetic waves Linear Polarization E and B fields E and B with another polarization E and B – Circular Polarization E and B – Elliptical Polarization http://phys23p.sl.psu.edu/phys_anim/EM/indexer_EM.html

Circularly Polarized Light Note: Definition of ‘handedness’ depends on the textbook from optics or engineering which you use. For our text book, use Right Hand Rule… Thumb in direction of light travel, fingers curl in direction that E Field is rotating.

Circularly Polarized Light DELAY x component relative to y component by 90 degrees in phase 90 degrees equivalent to λ/4 OR Use UPPER sign for Left Handed Circular polarization, BOTTOM sign for Right handed.

General Elliptical Polarization

Jones Vectors Jones Vector Factor of is included so that Jones Vector is NORMALIZED so that

Wire Grid Polarizer E E Field strongly reflects – E field tries to drive current in conducting wire…. Acts like a mirror. E Field mostly transmitted – width of wires too small to drive significant current. E

Polarizer

Polarizer – Arbitrary Angle Transmission Axis

Phase Change in Uniaxial Crystals Optical axis PARALLEL to surface in plane of page. EiP ne Optical Axis k no EiS L

Jones Matrix for waveplates If angle between LINEAR polarization of incoming light and Optical axis of ½ waveplate is θ, Output polarization is rotated by 2θ

Quarter waveplate If angle between LINEAR polarization of incoming light and Optical axis of 1/4 waveplate is 45 degrees, Output polarization is converted to CIRCULARLY polarized light. If angle is NOT 45 degrees, then in general get elliptically polarized light.

Multiple polarization Components-HW Problem

Liquid Crystal Display By pixilating the display, one can independently control transmission through each pixel. Did you ever notice that you can not see your car’s electronic display dashboard with polarizing sunglasses?

Polarizing Sunglasses

Photoelastic effect Birefringence in a material can be induced by mechanical stresses which enables one (put material between two crossed polarizers) to visualize location of stresses

Chiral Molecules

Chiral Molecules Because molecules are MIRROR images (image courtesy of WIKIPEDIA), there is a natural inclination to call them left handed and right handed molecules.

Rotation by Optical Activity E Chiral Solution E k k L Polarizer Polarizer

Optical Isolator