Information on infrared, UV, & white LEDs
LED lights have become vastly popular and have gained worldwide recognition over the last decade or so. LEDs have countless uses and are quickly becoming a favored choice for light sources. These lights are extremely reliable due to their long lasting power and brightness. LEDs are also very environmentally friendly. All of these characteristics combined are what makes LED lights the number one choice for many people when it comes to using them for projects, electronics, household needs, etc. LEDs are so reliable, in fact, that they are currently used to light up the world’s tallest spherical building. (the Globen Arena)
How exactly do LED lights work? The way in which an LED light is constructed varies greatly with that of an average light bulb. The LED actually “has a simple and strong structure. The beauty of the structure is that it is designed to be versatile, allowing for assembly into many different shapes. The light-emitting semiconductor material is what determines the LED’s color.”*
The LED is a diode that discharges light. According to www.colorkinetics.com:
A diode is a device that allows current to flow in only one direction. Almost any two conductive materials will form a diode when placed in contact with each other. When electricity is passed through the diode, the atoms in one material (within the semiconductor chip) are excited to a higher energy level. The atoms in that first material have too much energy and need to release that energy. The energy is then released as the atoms shed electrons to the other material within the chip. During this energy release, light is created. The color of the light from the LED is a function of the ingredients (materials) and recipes (processes) that make up the chip.
There are many advantages to LED lights, including long life, high reliability, high-levels of brightness, high intensity, as well as the fact that they contain no UV rays, amongst others.
There are several different kinds of LEDs available: visible LEDs, infrared LEDs, ultraviolet LEDs, and white LEDs.
LED colors are usually given in “nm” – nanometers. This is the wavelength of the light. “The wavelength given is the wavelength of the peak output-LEDs are not perfectly monochromatic, but rather produce wavelengths over a small region of the spectrum.”* The graph below compares Dominate Wave Lengths with their associated colors.
“The infrared band can be divided into Near Infrared (NIR) and Far Infrared (IR).”* Generally, far infrared is the thermal infrared used in order to detect hot objects, or to see when heat is leaking in a building. Far infrared is also “way beyond the range of LEDs.”* These LEDs are, at times, referred to as IREDS (Infra Red Emitting Diodes).
Ultraviolet light is divided into three bands:
· UV-A – which is fairly harmless
· UV-B – this is best known for causing sunburns
· UV-C - this UV is known to “kill things”
LED lights emit UV-A.
A very common wavelength for UV LEDs is 400 nm, which is on the border between violet and ultraviolet. A large portion of the light that is emitted through here is visible. Because of this fact, 400 nm UV LEDs are sometimes rated in millicandela, though as much as half of their energy is not visible. LEDs that have lower wavelengths are usually rated in milliwatts. It is also very important to mention that is it not safe at all to stare into an ultraviolet LED.
White light is a combination of all of the colors. Color Temperature refers to the measure of the amounts of red or blue. The higher color temperatures have more blue. It is also important to note that white LEDs have a color temperature, but monochromatic LEDs don’t.
Color Temperature Example
*Additional quotes and ideas courtesy of www.colorkinetics.com & www.gizmology.net/LEDs