ABSTRACT
ELECTROMAGNETIC SPECTRUM Electromagnetic energy radiated in the wavelength range from about 200 nm to 10.6 µ is commonly but technically incorrectly referred to as “light.” This spectral range encompasses ultraviolet (UV), visible (VIS), and infrared (IR) electromagnetic radiation. A more correct term, “optical radiation,” is also used to describe this energy because it behaves according to the laws and principles of geometric optics. Optical radiation may be characterized by the related quantities of wavelength, frequency, and photon energy ( 1 ). Below 200 nm, the atmosphere is a poor transmitter of optical radiation and above 10,600 nm (10.6 µ), this energy is known as heat and radio waves.
