1. Trivia Question Which famous New Jersey based scientist is credited with invention of the laser? (a) Albert Einstein (b) Niels Bohr (c) Charles Townes (d) Arthur Schawlow (e) Aleksandr Prokhorov (f) Nikolay Basov (g) Sheldon Cooper

2. Trivia Question Which famous New Jersey based scientist is credited with invention of the laser? (a) Albert Einstein – THEORETICAL foundations of lasers 1917 in Germany. (b) Niels Bohr – Argued that lasers would NOT work since they ‘violate’ Heisenberg uncertainty principle. (c) Charles Townes – Developed MASER (1953 Columbia University) and INFRARED laser (1957 – Bell labs in NJ). Nobel Prize 1964. (d) Arthur Schawlow (1957 – Bell labs in NJ) (e) Aleksandr Prokhorov (1964 Nobel Prize in physics for maser-laser principles) - USSR (f) Nikolay Basov (1964 Nobel Prize in physics for maser-laser principles) - USSR (g) Sheldon Cooper – He is a legend in his own mind. (h) Gordon Gould – graduate student at Columbia, coined the term LASER and successfully sued against US Patent Office for inventions related to the laser. Previous slide has copy of Gould’s notebook with first mention of word “LASER” Historians still argue about who invented the laser….

3. Interference of Two Waves Let’s consider interference of (a) co-linear waves and (b) waves overlapping obliquely (at some angle).

4. Wavefront Splitting Interferometers Fresnel Biprism Third animation from link below similar to Lloyd’s mirror http://physics- animations.com/Physics/English/1 wa_tmp.htm

5. Examples of co-linear interference (Interferometers)

6. Examples of Interferometers Mach-Zehnder Twyman-Green Rotating Sagnac Sample

7. Conservation of Energy in Interferometers

8. Reflection from a Boundary Phase of reflection from a boundary depends on mediums on both sides of the interface Reflection animation To be shown later in course: Wave passing from LOWER n to HIGHER n has a 180 degree phase change http://phet.colorado.edu/sims/wave-on-a- string/wave-on-a-string_en.html

9. Conservation of Energy in Interferometers

10. Interference of two waves at an angle theta

11. Sample Problem EX 2.5-2 Interference of two Point Sources - Movie Animation following crests of wave (constant phase)Point Source Notice location of nodes and anti-nodes

12. Multiple Slit Interference Sum of waves LARGEST when where n is an integer. Where does power come from to give LARGE power in the peaks?

13. Fabry-Perot filter

14. Fourier TIME transforms of Wave Function Real function u(r,t) has symmetric peaks for positive and negative frequencies

15. Fourier Transform of Pulses