1 Environmental Vision (OPT 6051) Laser Safety ELECTROMAGNETIC RADIATION

Electromagnetic radiation is energy in transit. In contrast to sound, which requires a medium through which to propagate, electromagnetic radiation can traverse empty space as well as a medium such as air or water. Different parts of the electromagnetic spectrum are identified with a particular wavelength. Out of the entire electromagnetic spectrum emitted by the sun, only two narrow bands, known as the radio window and optical window, penetrate the atmosphere and reach the earth. We are most interested in the optical window because it includes visible light, ultraviolet (UV) and infrared (IR) radiation. Although they are invisible to the human eye, UV and IR radiation are important in clinical optometry because of their interactions with ocular tissues. Table 1. UV, visible and IR electromagnetic radiation