Announcements 11/21/11 Prayer Exam 3 review session today, 5-6 pm, room C258 Lab 10 due tomorrow Exam 3 starts Monday after break, goes through Saturday Final exam: in Testing Center, M-Th week of finals Frank & Ernest Reading quiz Which of the following is NOT true of the 3D “wave vector”? a. Its magnitude is equal to 2p/l. b. In a plane wave, it points in the same direction everywhere in space. c. In a spherical wave, it points in the same direction everywhere in space. d. It tells us which way the wave is going. e. In 1D it reduces to the wave number k. Waves in 3-dimensions Plane waves a. polarization Wave vector a. direction of wave General Form E E0pˆ cos k x x k y y k z z t Specific Example E E0 Spherical waves 1 xˆ + yˆ cos kz t 2 Student-designed problem: Transverse Wave What direction do you want the wave to be traveling in? What direction do you want the wave to be oscillating in? What wavelength do you want the wave to have? What do you want the wave’s amplitude to be? What frequency (or velocity) do you want the wave to have? What do you want the overall phase of the wave to be? Lasers What makes a laser special? (answers from class) Actual laser spectrum is over 100 narrower than the width of the red line Laser spectrum Some of my answers: a. Single wavelength b. Intense c. Collimated d. Coherence (spatial, temporal) Blackbody spectrum Image & list from Wikipedia Lasers Stimulated Emission Emission Absorption Energy (light) (light, electrical, etc.) Principal components: 1. 2. 3. 4. 5. Gain medium Laser pumping energy High reflector Output coupler Laser beam light Green laser pointer More Wikipedia 5. laser beam 3. high reflector 1. gain medium (Nd:YVO4 crystal) 2. laser pumping energy (808 nm LED beam) 4. output coupler More Wikipedia Circular Polarization Remember these pictures? Blue & green both represent electric fields. Ex out of phase with Ey. Pictures from Wikipedia Optical Retarders, aka “Wave plates” Calcite crystal: Quartz, SiO2: no = 1.544, ne = 1.553 Calcite, CaCO3: no = 1.658, ne = 1.486 Pictures from Wikipedia