1. Reading Quiz
When a light ray hits a surface, the plane which contains the incoming, reflected, and transmitted beams, is called the “plane of _________”:
junction
incidence
normality
action
refraction

2. Reading Quiz
To represent the two electric field polarizations that are parallel and perpendicular to the place of incidence, we use the symbols:
n and w
p and q
r and u
s and p
t and v

3. What you learned in 123 “Normal incidence” A
We get complete picture in 471:
All angles
Polarization (refers to E direction, not to polarized atoms)
Complex index (next time)

4. Plane of incidence
(this page or y-z)
interface plane
(x-y)
Break linear polarization into two components:
s: “sticking out”
p: in plane of incidence
k vectors:

5. Unknowns we want to solve for:
Equations we must write:
Any one of these gives us
Frequency cons.
Reflection law
Snell’s law
Amazing!

7. Points farther down the interface are ahead in phase.
Huygen’s construction and Snell’s law:
Each point of space is imagined as a point source of forward semicircular waves. The sum of the circular wavefronts gives a wavefront of the real wave.
n=2
n=1
Points farther down the interface are ahead in phase.
They emit waves with different wavelength.  wave turns

8. Photon picture of Snell’s law
Photon energy
Photon momentum
From our findings for k and w across the interface, which is not conserved?
Photon energy
Photon momentum perpendicular to interface
Photon momentum parallel to interface
All are conserved
None are conserved

9. Continuing our calculation of r coefficients
The B field that must accompany Etp is_______.
Parallel to Etp
antiparallel to Etp
Into the page
Out of the page
Along k

10. The B field that must accompany Etp has magnitude _____
nEtp/c
ncEtp
cEtp/n
Etp/(cn)
Etp/c
Solving the 4 equations for our 4 unknown components of E gives us the Fresnel coefficients

11. Fresnel Coefficients

12. Suppose we have a laser beam entering a piece of glass under special conditions so R = 0.
What is the same for both beams?
Beam intensity
Beam power
both
neither

13. R and T from r and t

15. Wave amplitude, energy and
N-photons
A laser puts out power P (watts): How many photons per second leave it?
The beam is focused to an area A.
What is the average amplitude of the E-field?
What is the photon density photons/m3 in this case?
References

16. Photon picture
Suppose we have a laser beam entering a piece of glass at normal incidence. Assume it’s anti-reflection coated so we can ignore reflection.
In the glass the photons move slower.
The energy density u is ____ than in air.
larger
smaller
the same