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Transcript of 1 Polarization 1. Polarisation XY â€“ Plane: Plane of polarisation

• *Polarization*

• PolarisationXY Plane: Plane of polarisation

• S =(E x B)/o

• Unpolarized lightPolaroid: Transmits along the pass axis and absorbs along the perpendicular axis

• Malus law

• Unpolarized light

• Degree of polarisationIf the incident light is a mixture of unpolarised light of intensity Iuand polarised light of intensity Ip, then the transmitted light is given by:

• Polarisation by scattering

• Rayleigh scatteringBlue skyRed Sunset / Sunrise

• Convention

• - PolarisationPlane of polarisation is same as plane of incidence- PolarisationPlane of polarisation is perpendicular to the plane of incidence

• Polarisation by reflection

• Brewster angleGlasspartially polarisedlinearly polarisedunpolarised polarised

• Brewster angle

• = Brewster angleBrewsters law

• Polarisation by reflection

• Polarisation by double refraction- Two refracted beams emerge instead of one- Two images instead of oneCalciteQuartzOptic Axis: Uniaxial crystals exhibit cylindrical symmetry. There is a unique direction in a uniaxial crystal called the optic axis.Values of physical parameters along optic axis are different from the values perpendicular to it.

• CalciteExtraordinary rayOrdinary rayOptic axisPrincipalPlane:Plane contains optic axis and the direction of propagation

• CalcitePolariser/AnalyserOrdinary ray - polarised

• Extraordinary ray - polarised Calcite

• Polarisation by double refractionIsotropic Medium : Velocity Spherical

• - PolarisationPlane of polarisation is same as plane of incidence (principal plane)- PolarisationPlane of polarisation is perpendicular to the plane of incidence (principal plane)Plane of incidence : plane contains incident ray, reflected/refracted ray, surface normalPlane of polarisation : plane contains electric field vector and direction of propagation Principal plane : Plane contains optic axis and the direction of propagationThis definitionis considered in absence of Principal Plane

• e-ray : Plane of polarisation is same as principal plane Plane of polarisation is perpendicular to the principal plane o-ray : e-ray in general does not obey the laws of refraction except in case of special cut of crystal (optic axis) o-ray always obeys the laws of refraction Always e-ray carries -polarisation and o-ray carries -polarisation

• Positive and Negative uniaxial crystalsQuartz - Positive (ne - no)>0Calcite - Negative (ne - no) nove < voVelocity or Refractive index is the same along the OPTIC AXIS for o-ray and e-ray.ne < nove > vo

• QuartzPositive crystalSphereSpheroidWave surface is the locus of all points reached by the ray at a given instantVelocity ellipsoidne > nove < vo

• SphereSpheroidne > nove < voQuartzPositive crystal

• SphereSpheroidne > nove < voQuartzPositive crystal

• CalciteNegative crystalSphereSpheroidne < nove > vo

• SphereSpheroidne < nove > voCalciteNegative crystal

• SphereSpheroidne < nove > voCalciteNegative crystal

• Biaxial

• Huygensconstruction

• Calcitene < nove > vo

• Special cuts of uniaxial crystalOptic axis normal to the surface of incidenceNo double refraction

• Optic axis parallel to the surface of incidenceNo double refraction

• Oblique IncidenceOptic axis parallel to the surface of incidence, normal to the plane of incidence

• Nicol prismCalciteCanada balsamn = 1.55no = 1.6584ne = 1.4864

• Rochon prism

• Wollaston prism

• Elliptical and circular polarisationPlane polarisedCircularly polarisedEtc.

• Production of elliptically polarised lightOEAO =E =

• RetardersQuarter wave, Half wave and Full wave

• GLASS

• Quartz

• QuartzHalf wave plate

• Variable retarderBabinet Compensatoris a. . . . . . . . . . . . . . . . . . . .. . . . . . . . .C

• Interference of polarised lightFresnel-Arago lawsTwo coherent rays polarised at right angles do not interfere2. Two parallel coherent polarised rays will interfere in the same way as will ordinary light

• Optically active mediumSpecific rotation= 21.72 Deg/mmfor Sodium linesRotation of the plane of vibration & Rotatary dispersionDextrorotatary or right handed mediumLevorotatary or left handed medium

• Sugar, Glucose and FructoseSugar (Sucrose or Cane sugar) Glucose-D ( Dextrose or Grape sugar)Fructose (Levulose or Fruit sugar)Specific rotation52.766.47- 92ooo

• Specific rotation is defined as the observed rotation of light of wavelength 589 nm (the d line of a sodium lamp) passing through 10 cm of a 1 g ml-1 solution of a sample. Rotation in liquidsOne can find out the density of substance in solution[] = 10 / ldSpecific rotation, = angle of rotationl = Length of the liquid column in cmd = density in gm/cm3

• Fresnels explanation of rotation

• Induced Optical EffectsIsotropic medium can be made optically anisotropic applyingStress : Photoelastic EffectMagnetic field : Faraday EffectElectric field : Kerr effect