A radiometer is an instrument for detecting and measuring the radiant flux/power of electromagnetic radiation. The term radiometer usually refers to an infrared radiation detector; however, it also refers to detectors operating on any electromagnetic wavelength.
Types of Radiometers
The main types of radiometers are briefly explained below:
Crookes radiometer - Also known as the light mill, this radiometer was created by Sir William Crookes. It has an airtight glass bulb, within which four vanes of mica or aluminum foil revolve on a needle point. The bulb consists of partial vacuum.
Nichols radiometer - Created by Ernest Fox Nichols and Gordon Ferrie Hull, this radiometer is more sensitive than the Crookes type. It measures radiation pressure. It has a pair of small silvered glass mirrors, suspended in the manner of a torsion balance - using a fine quartz fiber within an enclosed space - in which air pressure is regulated.
Microwave radiometer – It operates in microwave wavelengths. The radiometer contains argon gas to enable it to rotate.
MEMS radiometer - Was invented by Patrick Jankowiak. The output signals from this radiometer can be quantized and signal processed, so as to determine the radiation level.
Advanced Very High Resolution Radiometer - It is a radiation-detection imager for remotely determining cloud cover and the Earth’s surface temperature. It is a scanning radiometer, and it consists of six detectors that collect different bands of radiation wavelengths.
Sources and Further Reading