Optical Fibers are made of silica and use total internal reflection to act as a guide for the light waves, therefore being more efficient than metal, having less loss and being immune to electromagnetic interference. The core is made of a transparent material, and is surrounded by a material with a lower refractive index. This allows total internal refraction to occur.
Prismatic Binoculars use prisms to direct light and utilise total internal reflection to prevent light loss from bouncing around in the binoculars itself.
Fingerprinting Devices use Frustrated Total Internal Reflection to map out the impression left by the friction ridges on our fingers.
The Rain sensor uses an infrared beam and shoots it at the windscreen at 45º angle. If the windscreen is wet, less light will return to the sensor.
Tan Siah Wei