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A radiometer is a device used to measure the radiant flux or power in electromagnetic radiation. Although the term is perhaps most generally applied to a device which measures infrared radiation, it can also be applied to detectors operating any wavelength in the electromagnetic spectrum; a spectrum-measuring radiometer is also called a spectroradiometer. In telecommunication and physics, radiometry is the science of radiation measurement. ...
It has been suggested that this article or section be merged with light. ...
Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High...
Whenever describing a radiometer, the most important characteristics are: - spectral range (what wavelengths) - spectral sensitivity (what sensitivity versus wavelength) - field of view (18 degrees or limited to a certain narrow field) - directional response (typically cosine response of uni-directional response)
Radiometers can use all kinds of detectors; some are " thermal" that is absorbing energy and converting that to a signal, some sense photons (photodiode) having a constant response per quantum (light particle). In a common application, the radiation detector within a radiometer is a bolometer which absorbs the radiation falling on it and, as a result, rises in temperature. This rise can then be measured by a thermometer of some type. This temperature rise can be related to the power in the incident radiation. Rendition of an imaging bolometer from Los Alamos National Laboratory A bolometer is a device for measuring incident electromagnetic radiation. ...
An early detector of infrared and visible radiation (light) was the Crookes radiometer. A more sensitive device, employing a different principle, is the Nichols radiometer. The Crookes radiometer, also known as the light mill or solar engine, consists of an airtight glass bulb, containing a partial vacuum. ...
A Nichols radiometer is the apparatus used by Nichols and Hull in 1901 for the measurement of radiation pressure. ...
A Microwave radiometer operates in the Microwave region of the electromagnetic spectum. The Microwave Radiometer (MWR) is an instrument that measures energy emitted by the atmosphere at very low energy levels (wavelengths much longer than red light also known as microwaves). ...
Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) frequencies, but relatively short for radio waves. ...
The term radiometer is occasionally used as shorthand for a Crookes radiometer, a device in which a rotor with dark and light vanes in a partial vacuum spins when exposed to light. The Crookes radiometer, also known as the light mill or solar engine, consists of an airtight glass bulb, containing a partial vacuum. ...
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