Announcements 10/31/11 Prayer Happy Halloween! Test going on… Pearls Before Swine.
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Transcript of Announcements 10/31/11 Prayer Happy Halloween! Test going on… Pearls Before Swine.
Horizontally Polarized LightHorizontally Polarized Light
Credit: the next few slides are from Dr. Durfee
Thought question What type of polarization is displayed in
the animation? http://stokes.byu.edu/emwave_flash.html
a. Horizontally polarizedb. Vertically polarizedc. Diagonally polarizedd. Other polarizede. Non-polarized
Thought question If you send horizontal linearly polarized
light through a (perfect) vertical polarizer, how much of the light intensity will get through?
a. 0-20%b. 20-40%c. 40-60%d. 60-80%e. 80-100%
Thought question If you send horizontal linearly polarized
light at 45 through a perfect vertical polarizer, how much of the light intensity will get through?
a. 0-20%b. 20-40%c. 40-60%d. 60-80%e. 80-100%
Thought question If you send circularly polarized light
through a perfect vertical polarizer, how much of the light intensity will get through?
a. 0-20%b. 20-40%c. 40-60%d. 60-80%e. 80-100%
Thought question (Like HW 27-2) If you send horizontal linearly
polarized light through a vertical polarizer, no light gets through because there is no component of the electric field in the light wave that is oscillating vertically. If you insert a diagonal polarizer at 45 between the two, how much of the light intensity will now get through the final polarizer?
a. 0-20%b. 20-40%c. 40-60%d. 60-80%e. 80-100%
Reading Quiz What do we call the angle at which light,
reflected off of a (non-conducting) surface, is completely polarized?
a. Brewster’s Angleb. Euler’s Anglec. Maxwell’s Angled. Snell’s Anglee. Sorenson’s Angle
Remember these? (Fresnel Coefficients)
2 1 1 2
1 2 1 2
v v n nrv v n n
2 1
1 2 1 2
2 2v ntv v n n
If near perpendicular (1-D problem)
2R r 2
1T r
For arbitrary angle (you don’t need to know for this class)
1 1 2 2.
1 1 2 2
cos cos
cos coss polarn n
rn n
1 2 2 1.
1 2 2 1
cos cos
cos cosp polarn n
rn n
1 1.
1 1 2 2
2 cos
cos coss polarn
tn n
1 1.
1 2 2 1
2 cos
cos cosp polarn
tn n
What is s-polar? What is p-polar?
When/what is phase shift?
Plots for air (n=1) to glass (n=1.5)s-polarization p-polarization
field amplitudes vs
intensities vs
20 40 60 80
1.0
0.5
0.5
r
t
20 40 60 80
0.2
0.4
0.6
0.8
1.0
R
T
20 40 60 80 0.2
0.2
0.4
0.6
0.8
1.0
r
t
20 40 60 80
0.2
0.4
0.6
0.8
1.0
R
T
field amplitudes vs
intensities vs Brewster’s angle!Do you always get a
180 phase shift upon reflection?
Fresnel Coefficients, cont.
2 1 1 2
1 2 1 2
v v n nrv v n n
2 1
1 2 1 2
2 2v ntv v n n
If near perpendicular (1-D problem)
2R r 2
1T r
For arbitrary angle (you don’t need to know for this class)
1 1 2 2.
1 1 2 2
cos cos
cos coss polarn n
rn n
1 2 2 1.
1 2 2 1
cos cos
cos cosp polarn n
rn n
1 1.
1 1 2 2
2 cos
cos coss polarn
tn n
1 1.
1 2 2 1
2 cos
cos cosp polarn
tn n
Set numerator = 0, apply Snell’s Law… lots of algebra/trig…
tan1 = n2/n1
Thought question
If you send an unpolarized beam at a piece of glass at Brewster’s angle, what happens?
a. The reflected beam is partially polarizedb. The reflected beam is completely polarizedc. The transmitted beam is partially polarizedd. The transmitted beam is completely
polarizede. More than one of the above
“Brewster windows”
If you send p-polarized light towards a piece of glass at Brewster’s angle, how much gets transmitted?
20 40 60 80 0.2
0.2
0.4
0.6
0.8
1.0
r
t
20 40 60 80
0.2
0.4
0.6
0.8
1.0
R
T
p-polarization
Thought question
In polarized sunglasses, some of the glare from the sun is eliminated when the sun is directly in front (and above) you. Should the polarizing material be aligned to allow vertical or horizontal electric field through?
a. verticalb. horizontal