Infrared motion detector
From Wikipedia, the free encyclopedia
 |
This article or section may require cleanup to meet Wikipedia's quality standards. Please help improve this article or replace this tag with a more specific message. This article has been tagged since February 2006. (help, talk) |
Infrared radiation exists on the electromagnetic spectrum with wavelengths longer than visible light; it cannot be seen but it is detectable. Everything that produces heat produces infrared radiation. Pyroelectric sensors made of crystalline material that creates a surface electric charge when it is subjected to a change in heat (in the form of infrared radiation). The change in electric charge is measured by a sensor and outputted. This sensor device is sensitive to wide range of wavelengths on the electromagnetic spectrum; therefore a filtering window (or lens) is used to limit the wavelengths to 8-14 micrometers which is most sensitive to human infrared radiation (9.4 micrometers being the strongest). A focusing device (Fresnel Lens) is used to correctly focus the incoming radiation. This lens can also be used to filter the radiation depending on the material it is made of. Because Infrared Radiation technology is passive, it is much more efficient than radar or ultrasonic; it doesn't send a signal and receive it, it simply takes input in. IR sensors look for the infrared radiation given off by humans, and as a human moves it detects the change in IR across its field of view.
