Applications of Total Internal Reflection (Preston)

Applications of Total Internal Reflection:

1. Optical Fibre (endoscopes, telecommunication)
1. “When light traveling in an optical dense medium hits a boundary at a steep angle (larger than the "critical angle" for the boundary), the light will be completely reflected. This is called total internal reflection. This effect is used in optical fibers to confine light in the core. Light travels along the fiber bouncing back and forth off of the boundary. Because the light must strike the boundary with an angle greater than the critical angle, only light that enters the fiber within a certain range of angles can travel down the fiber without leaking out. This range of angles is called the acceptance cone of the fiber. The size of this acceptance cone is a function of the refractive index difference between the fiber's core and cladding.” http://en.wikipedia.org/wiki/Optical_fiber
2. Rain Sensors to control automatic windscreen wipers
1. “The most common modern rain sensors are based on the principle total internal reflection. An infrared light is beamed at a 45-degree angle into the windshield from the interior — if the glass is wet, less light makes it back to the sensor, and the wipers turn on.” http://en.wikipedia.org/wiki/Rain_sensor#Automotive_sensors
3. Fingerprinting Devices
1. Uses frustrated Total Internal Reflection in order to record an image of a person’s fingerprint without the use of ink
4. Torchlights lenses