When light passes from glass or water to air (denser to rarer medium) ,it bends away from the normal .But when angle of incidence is greater than the critical angle 'C' ,the light rays reflect in the same denser medium.This phenomenon is called total internal reflection.
Total internal reflection is the phenomenon which occurs when a propagated wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is greater than the critical angle, the wave cannot pass through and is entirely reflected.
Applications:-
Total internal reflection is the operating principle of optical fibers, which are used in endoscopes and telecommunications.
Total internal reflection is the operating principle of automotive rain sensors, which control automatic windscreen/windshield wipers.
Another application of total internal reflection is the spatial filtering of light.
Prisms in binoculars use total internal reflection, rather than reflective coatings, to fold optical paths and show erect images.
Some multi-touch screens use frustrated total internal reflection in combination with a camera and appropriate software to pick up multiple targets.
Gonioscopy employs total internal reflection to view the anatomical angle formed between the eye's cornea and iris.
A gait analysis instrument, CatWalk XT, uses frustrated total internal reflection in combination with a high speed camera to capture and analyze footprints of laboratory rodents.
Optical fingerprinting devices use frustrated total internal reflection in order to record an image of a person's fingerprint without the use of ink.
A total internal reflection fluorescence microscope uses the evanescent wave produced by TIR to excite fluorophores close to a surface. This is useful for the study of surface properties of biological samples.
Total internal reflection is the operating principle of LED Light Panels. This technology utilizes LGPs (Light Guide Plates) as the vehicle for transmitting light over large areas. By etching a grid pattern on the second surface of the LGP, frustrated total internal reflection occurs allowing the light to escape the LGP as visible illumination.
Diamonds shine brightly due to total internal reflection