Announcements 11/19/10
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Prayer
TA won’t have office hours on Tuesday next week
(even though Tuesday = Friday classes).
Neither will I. (HW 36 = only 2 problems.)
Addition to Monday’s reading assignment: also
includes PpP chapter 10, “Modern optical devices”
Reading Quiz
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What does Rayleigh’s criterion tell us?
a. The angle at which both light polarizations
have equal reflection coefficients
b. The angle at which p polarized light has
minimum reflection
c. The angular separation resolvable by an
imaging system
d. The number of orders produced by a
diffraction grating
Circular Aperture, again
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What if there’s a lens in the hole?
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What if there isn’t a flat board?
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What if you have two light sources?
pattern at infinity
f
superimposed
pattern at focus
patterns at focus
What do you get in this situation?
2nd peak separated by at
least as much as
distance to first minimum
Rayleigh Criterion
Shape of curve
involves a “Bessel
function” (wait for
some future
Physics/Math class)
plotted vs (qD/l)
(using sinq  q)
Mathematica “FindRoot” command: qD/l = 1.21967
qmin.resolve  1.22
l
D
Rayleigh Criterion
Back to 1-D slits, infinitely narrow
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3 slits, equally spaced
(created with parameters so period = 2p)
Back to 1-D slits, infinitely narrow
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4 slits, equally spaced
Back to 1-D slits, infinitely narrow
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5 slits, equally spaced
Back to 1-D slits, infinitely narrow
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10 slits, equally spaced
Back to 1-D slits, infinitely narrow
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20 slits, equally spaced
Back to 1-D slits, infinitely narrow
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100 slits, equally spaced
What have we learned?
The Grating Equation
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Where will maxima be?
Resolving Power
N=100
Goes to zero at x=0.0628
= 2p/100
width = 1/N 
separation of
maxima
140
120
100
80
60
40
20
0.4
0.2
0.0
0.2
0.4
Resolving Power
Red light vs. Green light
HW 36-5: resolving power = Dl/l = Nm
Demos
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Circular aperture
Diffraction grating
… with two lasers
… with white light source
Reading Quiz
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What do we call diffraction off of the ions in
a crystal?
a. Bragg diffraction
b. Bohr diffraction
c. Compton diffraction
d. Raman diffraction
e. Thompson diffraction
X-ray Diffraction by Crystals
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Bragg equation
http://commons.wikimedia.org/
wiki/File:Bragg_diffraction.png
http://l-esperimento-piu-bello-dellafisica.bo.imm.cnr.it/english/history/figuredett2.html
Laue Patterns
http://www.neutronoptics.com/laue.html