By TONY DENAMI
Understanding UV— For most people visual light ranges from about 380 to 740 nm.
T
he human eye can see objects due to reflected light in the visual light spectrum. Light behaves like a wave, which has different properties that cause the light to manifest itself in different ways, one of them being wavelength (see image below).
Granted, waves of light do not just exist to help us see. Light acts as a way of transporting energy, meaning that lighting is constantly operating around us, despite us not being able to see it. Some examples of this include x-rays used in a doctor’s office and infrared light used for night vision and thermal imaging. For most people this visual light ranges from about 380 to 740 nanometers. Nanometers is the scale to which electromagnetic radiation is measured similar to the way that Fahrenheit measures temperature. There are seven color wavelengths within the 380 to 740 spectrums; in descending order they are red, orange, yellow green, blue, indigo and violet. Below the human visual level of 380 nanometers is the ultra violet or UV wavelength. Not all light is safe, ultraviolet (or UV) light being one of them.
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designing lighting
Most people have heard of UV light, having been warned about its connection to sunburns, tanning, and overexposure to sunlight. They know that the sun gives off UV rays, causing us to tan, but also making us more susceptible to sunburns, wrinkles, leathery skin, and even skin cancer. Most do not know, however, that UV light can be further categorized into three groups: UV-A, UV-B, and UV-C. UV-A light exists below the visible spectrum, which is why we cannot see it, and it is also the most abundant type of UV light in the atmosphere, accounting for up to 95%. UV-A light ranges from 315 to 400 nanometers. Commonly referred to as blacklight, UV-A is the least dangerous and is used more commonly than the other types of UV light. Many of us have seen UV-A in action at malls, night clubs, or art installations, and many restaurants and food processing facilities use UV-A to trap and kill germ-carrying bugs.
