Applications of Total Internal Reflection by Izzat and Joel

Applications:

1. To make diamonds sparkle

- The cut of the diamond favors total internal reflection. Most rays entering the top of the diamond will internally reflect until they reach the top of the face of the diamond where they exit. This gives diamonds their bright sparkle and hence, look more attractive.

2. To make information travel rapidly on light waves through a fiber optic
- A fiber optic is a glass "hair" which is so thin that once light enters one end, it can never strike the inside walls at less than the critical angle. The light undergoes total internal reflection each time it strikes the wall. Only when it reaches the other end is it allowed to exit the fiber.

- Fiber optic cables are used to carry telephone and computer communications. Advantages over electrical wired include:

1. Fiber optics can carry much more information in a much smaller cable.
2. No interference from electromagnet fields result in "clearer" connections.
3. No electrical resistance.
4. No hazard of electrocution if cable breaks.

3. Prismatic binoculars

- Uses the principle of total internal reflections to get a very clear image

4. Automative rain sensors

- The most common modern rain sensors are based on the principle of 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. Most vehicles with this feature have an "AUTO" position on the stalk.

5. Flashlight lenses
- The X200A LED Handgun WeaponLight uses a total internal reflection (TIR) lens that is precision molded from a special cyclo-olefin polymer. The lens surrounds the LED, gathering virtually all of its light, which it reflects and refracts forward in an exceptionally tight beam that cannot be duplicated with a reflector.







Sources:
- http://www.surefire.com/why_surefire#Lenses
- http://en.wikipedia.org/wiki/Total_internal_reflection#Applications
- http://en.wikipedia.org/wiki/Rain_sensor#Automotive_sensors
- http://en.wikipedia.org/wiki/Binoculars#Prism_binoculars
- http://regentsprep.org/Regents/physics/phys04/captotint/default.htm