The 2009 Nobel Prize in Physics will be shared by physicists who each made important contributions to our understanding of light. Applications of these contributions have proven to be particularly influential on modern life, including such innovations as digital cameras and the internet itself. Half of this years prize will go to Charles Kuen Kao, whose insights into the optimization of the transmission of light through glass made fiber optic cables a reality. The other half will be shared by Willard Sterling Boyle and George Elwood Smith for their work on charge-coupled devices, the underlying technology within most digital cameras.

Charles Kuen Kao certainly was not the first to come up with the idea of using glass to transmit light. Humans have been employing this effect for decorative purposes for centuries, and practical applications - such as shining light into small cavities for surgeries - have been in use since the 30s. The basic effect of guiding a beam of light along a thin cylinder of glass relies on the difference in refractive indices between the glass and air causing total internal reflection, keeping the light contained. However, at the time it was widely assumed that this effect could never be useful over long distances due to the rapid decay of the light's intensity. Physical imperfections in the glass wire were blamed for this decay, but no better technique for manufacturing them could be found. However, in 1966 Kao suggested that it was not the physical impurities of the wire, but rather the chemical impurities in the glass itself that was to blame. He encouraged the industry to work towards better and better manufacturing methods, making possible the fiber optic cables that can send infrared light signals around the world today.
 
Originally hoping to merely improve the performance of digital memory, Willard Boyle and George Smith of Bell Laboratories ended up paving the way for a whole new type of imaging technology. Nowadays, digital imagers are everywhere, from phones, to telescopes, to consumer cameras, but it was Boyle and Smith who first brainstormed the idea of utilizing the photoelectric effect to store an image in digital form. By taking advantage of light's ability to excite and free electrons on the surface of a semiconductor, CCD arrays allow for the measurement of light intensity at each pixel. The liberated electrons are stored in potential wells and counted pixel by pixel, forming an image of the incident light intensity. By utilizing a pattern of filters within the array, the relative intensity of different frequencies of light can be examined as well, making possible the high-resolution digital color images that we use today.

More information on these physicists and the Nobel Prize itself can be found at http://nobelprize.org/nobel_prizes/physics/laureates/2009/