Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz).
In the aerospace context, "infrared" refers to a specific part of the electromagnetic spectrum that is characterized by wavelengths that are longer than those of visible light but shorter than those of radio waves. Infrared radiation is emitted by objects that are at a temperature above absolute zero, and it is often used in the aerospace industry for a variety of purposes, including imaging, sensing, and communication.
There are several different types of infrared radiation, including near-infrared, mid-infrared, and far-infrared. Near-infrared radiation has wavelengths that are just beyond the visible spectrum, and it is used for applications such as imaging and sensing. Mid-infrared radiation has wavelengths that are longer than near-infrared radiation, and it is used for applications such as spectroscopy and thermal imaging. Far-infrared radiation has wavelengths that are even longer than mid-infrared radiation, and it is used for applications such as thermal imaging and remote sensing.
Examples of aerospace applications that use infrared radiation include imaging and sensing systems for aircraft and spacecraft, thermal management systems for electronic components, and communication systems for satellite and other space-based applications. Infrared radiation is an important part of the aerospace industry, and it plays a critical role in a variety of applications.