Announcements 10/31/11

1. Announcements 10/31/11 • Prayer • Happy Halloween! • Test going on… Pearls Before Swine

2. Horizontally Polarized Light Credit: the next few slides are from Dr. Durfee

3. Vertically Polarized Light

4. Diagonally Polarized Light

5. Circularly Polarized Light

6. Elliptically Polarized Light

7. Unpolarized Light

8. Thought question • What type of polarization is displayed in the animation? http://stokes.byu.edu/emwave_flash.html • Horizontally polarized • Vertically polarized • Diagonally polarized • Other polarized • Non-polarized

9. Circularly Polarized, pictures Pictures from Wikipedia

10. Polarizers • Polaroid film • Crystals • Lines of wires • Polaroid Film • Crystals www.thorlabs.com

11. Thought question • If you send horizontal linearly polarized light through a (perfect) vertical polarizer, how much of the light intensity will get through? • 0-20% • 20-40% • 40-60% • 60-80% • 80-100%

12. 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? • 0-20% • 20-40% • 40-60% • 60-80% • 80-100%

13. Thought question • If you send circularly polarized light through a perfect vertical polarizer, how much of the light intensity will get through? • 0-20% • 20-40% • 40-60% • 60-80% • 80-100%

14. 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? • 0-20% • 20-40% • 40-60% • 60-80% • 80-100%

15. Demos • Polarization configurations

16. Reading Quiz • What do we call the angle at which light, reflected off of a (non-conducting) surface, is completely polarized? • Brewster’s Angle • Euler’s Angle • Maxwell’s Angle • Snell’s Angle • Sorenson’s Angle

17. Remember these? (Fresnel Coefficients) • If near perpendicular (1-D problem) When/what is phase shift? • For arbitrary angle (you don’t need to know for this class) What is s-polar? What is p-polar?

18. t t r r T T R R Plots for air (n=1) to glass (n=1.5) s-polarization p-polarization field amplitudes vs q field amplitudes vs q Brewster’s angle! intensities vs q intensities vs q Do you always get a 180 phase shift upon reflection?

19. Fresnel Coefficients, cont. • If near perpendicular (1-D problem) • For arbitrary angle (you don’t need to know for this class) Set numerator = 0, apply Snell’s Law… lots of algebra/trig… tanq1 = n2/n1

20. Thought question • If you send an unpolarized beam at a piece of glass at Brewster’s angle, what happens? • The reflected beam is partially polarized • The reflected beam is completely polarized • The transmitted beam is partially polarized • The transmitted beam is completely polarized • More than one of the above

21. t r T R “Brewster windows” p-polarization • If you send p-polarized light towards a piece of glass at Brewster’s angle, how much gets transmitted?

22. 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? • vertical • horizontal

23. Demo • Flashlight reflecting off of glass