An infrared lamp is a light source that only emits infrared light. There are several different applications for these devices, and each has slightly different methods of operation. There are two common divisions among these devices: a near infrared lamp will create light, and often heat, when used but a full infrared light doesn’t create effect visible by human eyes. These lamps are used in everything from remote controls to fast food restaurants to bathrooms.
The part of the light spectrum visible to human eyes is actually a very small portion of a much larger thing. Visible light is bracketed by two forms of radiation that are frequently used in modern technology: ultraviolet and infrared. Both of these light ranges have many useful applications, even though the vast majority of people can’t see them.
The side containing infrared is the lower energy section. The waves are longer and travel slower than the higher forms of light, which provides them with a select group of very useful properties. One of the more common is its heating properties. The slower-moving energy will heat objects that are exposed to it. This is the technology used in the heating lamps that keep food in restaurants warm as well as heat bathrooms and saunas.
Most of those types of infrared lamps emit visible light. This is generally done so users can tell they are turned on; a invisible lamp could cause burns even in total darkness. This generally means they are a near infrared lamp, meaning the light emitted straddles the border between visible red light and infrared.
Non-visible infrared lights are completely invisible to most people. These lights are everywhere; they operate remote controls, automatic door openers at stores and even let users send songs to other people with the same type of MP3 player. These lights are very small and designed to not give off excess heat, meaning that users can’t be burnt by a remote control.
These devices generally work in one of two ways: beam interruption and pulsed communication. Beam interruption is used for automatic doors and is by far the simpler of the two. The infrared lamp sends out a field of light that points down at the area around the door. When something breaks the field, such as a person approaching the door, the lamp recognizes the interruption and opens the door until the interference goes away.
Pulsed communication is used for most other forms of infrared communication. Nearly all remotes have a portion where the covering is semi-transparent. This panel covers the infrared lamp. When a button is pressed on the remote, the lamp flashes a preset code out into the room. The receiver on the device is constantly looking for infrared signals and when it sees the pulse, it activates the process that the pulse corresponds too.