Optical Optical Phenomena & Phenomena & Other Uses of Other Uses of

LightLight

Types of Optical Types of Optical PhenomenaPhenomena

1.1. Total Internal ReflectionTotal Internal Reflection2.2. Atmospheric RefractionAtmospheric Refraction3.3. DispersionDispersion4.4. Lens AberrationsLens Aberrations

Total Internal ReflectionTotal Internal Reflection

The complete reflection of light at the boundary of two transparent media.

Total Internal ReflectionTotal Internal ReflectionOccurs when light travels from a medium with a higher n value to a medium with a lower n value. (ex. From water to air)

WATER

AIR

θc

θc = Critical Angle = angle at which total internal reflection occurs.

Total Internal ReflectionTotal Internal Reflection

Snell’s law can be used to find the critical angle.

ni (sin θc) = nr (sin 90)sin θc = nr/ni

* For total internal reflection to occur, nr is always less than ni.

Total Internal ReflectionTotal Internal Reflection(Fiber Optics)(Fiber Optics)

Atmospheric RefractionAtmospheric Refraction

The sun is visible before actual sunrise and after actual sunset.

Atmospheric Refraction Atmospheric Refraction (Mirages)(Mirages)

DispersionDispersion

Separation of polychromatic light (white light) to its component wavelengths.Light bends more from red to violet.

Dispersion (Rainbows)Dispersion (Rainbows)

Rainbows are created by dispersion of light in water droplets.

Lens Aberrations Lens Aberrations (spherical)(spherical)

Spherical aberrations are caused because spherical surfaces are not the ideal shape with which to make a lens, but they are by far the simplest shape to which glass can be ground and polished.

Image imperfections caused by approximations of the focal length in the lens theory.

Lens Aberrations Lens Aberrations (chromatic)(chromatic)

Chromatic aberrations occur when different colors of light focus at different distances behind a lens.

Lens Aberrations Lens Aberrations (chromatic)(chromatic)

Aberration

No Aberration- corrected/reduced by using a

combination of converging and diverging lenses of two different types of glass.