Optics and Photonics

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Optics and Photonics

• Dr. Kevin Hewitt
• Office Dunn 240, 494-2315
• Lab Dunn B31, 494-2679
• Kevin.Hewitt_at_Dal.ca
• Friday Sept. 6, 2002

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Course Information

• Optics is light at work
• Textbook Optics (4th edition), Eugene Hecht,
  152.39
• Reference Introduction to Optics, F. L.
  Pedrotti,
• Description Two areas will be covered
• Geometrical optics ? lt dimension of
  aperture/object
• Wave (i.e. physical) optics ? gt dimension of
  aperture/object
• Selected topics
• What are your areas of interest?
• Lasers, holography, fiber optic communication,
  functions of the eye
• Pre-requisites PHYC 2010/2510 and MATH 2002

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Course Information

• Grading
• Problem sets 20
• Midterm 20
• Oral Presentation 20
• Final exam 40
• Problem sets
• 1 per week
• Hand-out/Hand-in every Wednesday (begin Sept. 11)

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Class Schedule
Week Dates Topic Key terms
1 Sept. 6 The Nature of light Wave-particle duality
2 Sept. 9-14 Geometrical optics Huygens and Fermats principles Reflection, refraction, thin lens
3 Sept. 16-21 Matrix methods in paraxial optics System matrix elements, thick lens, cardinal points, Ray transfer matrix
4 Sept. 23-28 Optical instrumentation Optics of the eye Stops, pupils, windows, prisms, cameras, telescopes, Acuity, corrections
5 Sept. 30-Oct. 4 Wave equations and superposition Plane and EM waves, Doppler effect
6 Oct. 7-12 Interference of light Youngs double slit, Dielectric films, Newtons rings
7 Oct. 14-19 Optical Interferometry Michelson, Fabry-Perot, Resolving power, Free spectral range.
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Class Schedule
Week Dates Topic Key terms
8 Oct. 21 -26 Fraunhofer diffraction Single slits, multiple slits, rectangular and circular apertures
9 Oct. 28-Nov.1 Gratings Grating equation, Free Spectral Range, Dispersion, Resolution
10 Nov. 4 - 9 Polarization of light Fresnel equations, Jones vector, birefringence, optical activity, production
11 Nov. 11 - 16 Laser basics and applications Einsteins theory, Laser Tweasers
12 Nov. 18 - 23 Fiber optics Fourier optics Bandwidth, attenuation, distortion, optical data imaging and processing
13 Nov. 25 -30 Holography Class Presentations
14 Dec. 2 Classes end
15 Dec. 4 - 14 Exam period 3 hour exam
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Key Dates
Date Item
September 20 Last Day to Register
October 7 Last Day to Drop without a w
October 14 Thanksgiving Day
October 12 Midterm exam
November 11 Remembrance day
November 4 Last Day to drop with a W
Nov. 25-30 Oral Presentations
December 2 Classes end
December 4-14 Exam period
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Nature of Light (Hecht 3.6)
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Nature of Light

• Particle
• Isaac Newton (1642-1727)
• Optics
• Wave
• Huygens (1629-1695)
• Treatise on Light (1678)
• Wave-Particle Duality
• De Broglie (1924)

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Young, Fraunhofer and Fresnel(1800s)

• Light as waves!
• Interference
• Thomas Youngs (1773-1829) double slit experiment
  
• see http//members.tripod.com/vsg/interf.htm
• Diffraction
• Fraunhofer (far-field diffraction)
• Augustin Fresnel (1788-1827) (near-field
  diffraction polarization)
• Electromagnetic waves
• Maxwell (1831-1879)

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Max Plancks Blackbody Radiation (1900)

• Light as particles
• Blackbody absorbs all wavelengths and
  conversely emits all wavelengths
• The observed spectral distribution of radiation
  from a perfect blackbody did not fit classical
  theory (Rayleigh-Jeans law) ? ultraviolet
  catastrophe

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Cosmic black body background radiation, T 3K.
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Plancks hypothesis (1900)

• To explain this spectra, Planck assumed light
  emitted/absorbed in discrete units of energy
  (quanta),
• E n hf
• Thus the light emitted by the blackbody is,

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Photoelectric Effect (1905)

• Light as particles
• Einsteins (1879-1955) explanation
• light as particles photons

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Luis de Broglies hypothesis (1924)

• Wave and particle picture
• Postulated that all particles have associated
  with them a wavelength,

• For any particle with rest mass mo, treated
  relativistically,

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Photons and de Broglie

• For photons mo 0
• E pc
• Since also E hf

• But the relation c ?ƒ is just what we expect
  for a harmonic wave

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Wave-particle duality

• All phenomena can be explained using either the
  wave or particle picture
• Usually, one or the other is most convenient
• In OPTICS we will use the wave picture
  predominantly

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Propagation of light Huygens Principle (Hecht
4.4.2)

• E.g. a point source (stone dropped in water)
• Light is emitted in all directions series of
  crests and troughs

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Terminology

• Spherical waves wave fronts are spherical
• Plane waves wave fronts are planes
• Rays lines perpendicular to wave fronts in the
  direction of propagation

Planes parallel to y-z plane
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Huygens principle

• Every point on a wave front is a source of
  secondary wavelets.
• i.e. particles in a medium excited by electric
  field (E) re-radiate in all directions
• i.e. in vacuum, E, B fields associated with wave
  act as sources of additional fields

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Huygens wave front construction
Construct the wave front tangent to the wavelets
What about r direction? See Bruno Rossi Optics.
Reading, Mass Addison-Wesley Publishing Company,
1957, Ch. 1,2 for mathematical explanation
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Plane wave propagation

• New wave front is still a plane as long as
  dimensions of wave front are gtgt ?
• If not, edge effects become important
• Note no such thing as a perfect plane wave, or
  collimated beam