Since the late 1950s, optical fibers have emerged as revolutionary tools in the fields of medicine and telecommunications. They are capable of transmitting light pulses containing data up to 13,000 miles (20,917 km) without significant distortion. They also permit the "piping" of light into otherwise inaccessible locations, making them useful in diagnostic procedures which would have previously required invasive surgery.

Optical fibers operate on the principle of total internal reflection. Every medium through which light can pass possesses a certain refractive index, the amount by which a beam of light is bent as it enters the medium. As the angle at which the light strikes the medium is decreased from the perpendicular, a point is reached at which the light is bent so much at the surface that it reflects completely back into the medium from which it originated; thus, the light will bounce back rather than escape...