Applications

Light is applied to many different and diverse tasks in our every day life. Microwave ovens use low frequency light to cook food, a remote control communicates with the television via infrared or ultraviolet beams, doctors use lasers for precise surgery and so on.

Here you can read a few specific examples of the application of light to improve our daily lives.

Laser therapy for ocular defects

Laser beams, both pulsed and continuous, are currently used to treat glaucoma, retinal bleeding, macular degeneration, retinal detachments, and opacified intraocular membranes. Angle blockage glaucoma, a disease of the eye characterized by increased fluid pressure within the eye and leading progressively to blindness, is treated with argon (A) and neodymium: yttrium aluminum garnet (YAG) lasers. The treatment consists of repairing structural flaws in the eye that cause increased pressure, using the laser beam to open up blocked ducts or to create new canals for better drainage between the chambers of the eye. The laser is also used effectively to treat diabetic retinopathy, the leading cause of blindness. To neutralize such organic disorders, the thermal energy in a laser beam is used on the retina in such a way that it prevents the harmful growth or rupture of new, unwanted blood vessels (neovascularization). The thermal content of a laser beam, so effective where retinal coagulation is required, is also used to tack or weld retinas that fall away from the choroid at peripheral positions. This procedure, in fact, was the first successful use of lasers in a clinical environment.

Lasers are also used in CD players. A laser beam is focused to a very small point on the silvered surface of the CD. If the CD has a pit in that spot light is scattered, otherwise light is reflected back. The pattern of pits and flat surfaces on the CD can be used to encode data (music, pictures, programs for the computer, etc.).

Television uses an electron beam which rapidly scans across the screen to excite phosphorus atoms on the screen, which in turn give off visible light. Electrons have different intensities when they hit different parts of the screen causing a picture to form on it. For us to see color television 3 different beams of electrons are used, each beam exciting a phosphorus which gives off light in one of the three main colors (red, green, blue) which blend together to create a wide variety of colors.