Trivia Question Under President Ronald Reagan, what was the nickname of the science initiative to develop, among other things, a laser which could should down a ballistic missile? (a) The Bourne Initiative (b) Avatar Missile System (c) The 2001 Initiative (d) Star Wars Initiative (e) Metal Storm

Diffraction: Light does not like to be confined

Examples of Diffraction Knife edge Light passing by a sharp edge

Examples of Diffraction Waves passing through a small hole

Examples of Diffraction Focusing light with a lens Geometric Optics – Wavelength small compared to other dimensions. No Diffraction. Light focuses to a point. Wave Optics – Wavelength can be comparable to other dimensions. Diffraction MUST be considered. Light focuses to a minimum spot size. oo

Fresnel Diffraction (near-field) Fraunhoffer Diffraction (far-field) Increasing Distance

N=2

N=5

N=10

Diffraction Gratings Transmission GratingReflection Grating

Diffraction Gratings Spectrometers

Calculation of Diffraction Patterns MathCad file

Diffraction through MULTIPLE Slits Diffraction Interference of N sources

Diffraction through MULTIPLE Slits Diffraction Interference of N sources Mathcad File

Examples of Diffraction Focusing light with a lens Geometric Optics – Wavelength small compared to other dimensions. No Diffraction. Light focuses to a point. Wave Optics – Wavelength can be comparable to other dimensions. Diffraction MUST be considered. Light focuses to a minimum spot size. oo

Resolution Limits of Diffraction Diffraction Limitations on Resolving Two Sources Diffraction Limits and Aperture Size Diffraction Limits and Wavelength Diffraction limits your ability to resolve two sources Changing an Aperture size (or size of Lens) limits the resolution of two sources The larger the wavelength, the lower the resolution in resolving objects – eg. Blue lasers for CD readers

Diffraction Gratings Transmission GratingReflection Grating