Pyrometer

In the modern usage, it is a device that from a distance determines the temperature of a surface from the amount of the thermal radiation it emits, a process known as pyrometry, a type of radiometry.

The word pyrometer was originally coined to denote a device capable of measuring the temperature of an object by its incandescence, visible light emitted by a body which is at least red-hot.

[citation needed] The term "pyrometer" was coined in the 1730s by Pieter van Musschenbroek, better known as the inventor of the Leyden jar.

[9] As the ratio pyrometer came into popular use, it was determined that many materials, of which metals are an example, do not have the same emissivity at two wavelengths.

To more accurately measure the temperature of real objects with unknown or changing emissivities, multiwavelength pyrometers were envisioned at the US National Institute of Standards and Technology and described in 1992.

Reliable and continuous measurement of the metal temperature is essential for effective control of the operation.

Smelting rates can be maximized, slag can be produced at the optimal temperature, fuel consumption is minimized and refractory life may also be lengthened.

Thermocouples were the traditional devices used for this purpose, but they are unsuitable for continuous measurement because they melt and degrade.

[14] The tuyère pyrometer is an optical instrument for temperature measurement through the tuyeres, which are normally used for feeding air or reactants into the bath of the furnace.

A hot air balloon is equipped with a pyrometer for measuring the temperature at the top of the envelope in order to prevent overheating of the fabric.

Timing combined with a radial position encoder allows engineers to determine the temperature at exact points on blades moving past the probe.