SCPY152 General Physics II June 19, 2015 Udom Robkob, Physics-MUSC 3 Wave Optics SCPY152 General Physics II June 19, 2015 Udom Robkob, Physics-MUSC

Topics Light waves Phasor Huygens’s principle Law of superposition Double slit interference Multiple slit interference Thin films Single slit diffraction Single hole diffraction Double slit diffraction Grating diffraction

Light Waves Light waves Plane wave = sinusoidal field

Phasor Rotating vector = phasor

Law of Superposition Law of superposition

Law of Superposition Phasor diagram

Double Slit Interference Coherent light source = monochromatic light sources generate light waves in phase Young double slit experiment

Double Slit Interference Path different y

Double Slit Interference Path different y What is equation for destructive interference?

Multiple Slits Interference In case of triple slit interference

Multiple Slits Interference In case of triple slit interference Three phasors are determined

Multiple Slits Interference In case of triple slit interference Three phasors are determined

Multiple Slits Interference In case of triple slit interference Three phasors are determined Let try to analyze four slit interference pattern!

Interference from Thin Films Let us determine thin transparence film of refractive index n and thickness d. There are interferences at the front side and back side of the film. We determine interference between light come from the front surface and the back surface of the film.

Thin Film Interferences In case of front side interference The interference depends on path different “2d” and phase different of the two light beams

Thin Film Interferences In case of n>no, the first beam has phase shift from reflection at the front surface but not the second beam Destructive Interference:

Thin Film Interferences Exercise

Thin Film Interferences Exercise

Thin Film Interferences In case of non-uniform film

Thin Film Interferences In case of non-uniform film In case of n>n0, for destructive interference

Thin Film Interferences Newton’s rings R

Thin Film Interferences Newton rings analysis

Diffraction Phenomena We can see light diffraction in many places

Huygens’s Principle Huygens’s principle “Every point on the wave front becomes a new source of the wave"

Single Slit Diffraction

Single Slit Diffraction Phasor analysis

Single Slit Diffraction Phasor analysis

Single Slit Diffraction Phasor analysis-destructive interference Path different

Single Slit Diffraction Phasor analysis-destructive interference Path different

Double Slits Diffraction Double slit diffraction