Infraredwavelength range

Light waves are transverse: that is, the vibrating electric vector associated with each wave is perpendicular to the direction of propagation. A beam of unpolarized light consists of waves moving in the same direction with their electric vectors pointed in random orientations about the axis of propagation. Plane polarized light consists of waves in which the direction of vibration is the same for all waves. In circular polarization the electric vector rotates about the direction of propagation as the wave progresses. Light may be polarized by reflection or by passing it through filters, such as certain crystals, that transmit vibration in one plane but not in others.

Near-infraredwavelength

NIR and SWIR together is sometimes called “reflected infrared”, whereas MWIR and LWIR is sometimes referred to as “thermal infrared”.

Infrared (IR), sometimes called Infrared Light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the huhttps://madpcb.com/glossary/electromagnetic-radiation/man eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (frequency 430THz) (although the longer IR wavelengths are often designated rather as terahertz radiation. Black-body radiation from objects near room temperature is almost all at IR wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, with properties corresponding to both those of a wave and of a particle, the photon.

IR radiation is emitted or absorbed by molecules when changing rotational-vibrational movements. It excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. IR spectroscopy examines absorption and transmission of photons in the IR range.

Infraredwavelength rangein nm

Infraredlight

These divisions are not precise and can vary depending on the publication. The three regions are used for observation of different temperature ranges, and hence different environments in space.

The International Commission on Illumination (CIE) recommended the division of infrared radiation into the following three bands:

The most common photometric system used in astronomy allocates capital letters to different spectral regions according to filters used; I, J, H, and K cover the near-infrared wavelengths; L, M, N, and Q refer to the mid-infrared region. These letters are commonly understood in reference to atmospheric windows and appear, for instance, in the titles of many papers.

In optical communications, the part of the IR spectrum that is used is divided into seven bands based on availability of light sources transmitting/absorbing materials (fibers) and detectors:

Infraredwavelength

Infrared radiation is used in industrial, scientific, military, commercial, and medical applications. Night-vision devices using active near-IR illumination allow people or animals to be observed without the observer being detected. IR astronomy uses sensor-equipped telescopes to penetrate dusty regions of space such as molecular clouds, to detect objects such as planets, and to view highly red-shifted objects from the early days of the universe. IR thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect the overheating of electrical components.

polarization, property of certain electromagnetic radiations in which the direction and magnitude of the vibrating electric field are related in a specified way.

infrared中文

Military and civilian applications include target acquisition, surveillance, night vision, homing, and tracking. Humans at normal body temperature radiate chiefly at wavelengths around 10μm (micrometers). Non-military uses include thermal efficiency analysis, environmental monitoring, industrial facility inspections, detection of grow-ops, remote temperature sensing, short-range wireless communication, spectroscopy, and weather forecasting.

The C-band is the dominant band for long-distance telecommunication networks. The S and L bands are based on less well-established technology, and are not as widely deployed.

Infrared radiation was discovered in 1800 by astronomer Sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. Slightly more than half of the energy from the Sun was eventually found, through Herschel’s studies, to arrive on Earth in the form of IR. The balance between absorbed and emitted IR radiation has an important effect on Earth’s climate.

Infrared radiation extends from the nominal red edge of the visible spectrum at 700 nanometers (nm) to 1 millimeter (mm). This range of wavelengths corresponds to a frequency range of approximately 430 THz down to 300 GHz. Beyond IR is the microwave portion of the electromagnetic spectrum.