Typical Multi-Wavelength Application

Multi-wavelength infrared thermometers are used for applications where single- and dual-wavelength sensors are not able to provide the required accuracy. There are inherent limitations in the single- and dual- wavelength design and many of these issues are overcome with the new and advanced multi-wavelength design. For example, the multi-wavelength sensor is used to measure non grey body materials such as aluminum, copper, stainless steel, silicon alloy steel, and chrome. These materials all have a very low emissivity and non-conforming spectral distribution.

The classic multi-wavelength temperature application is isothermal (constant temperature) extrusion of aluminum. Multi- wavelength sensors are used to measure the temperature of the preheated billet and the aluminum profile exiting the press die. The press exit temperature is held constant by adjusting the speed of the press. Constant press exit temperature is used to control the dimensional and physical properties of the extrusion over the full length of the extrusion. Typically the tail end of the extrusion gets hotter and this affects product quality and uniformity. The emissivity of the aluminum at the press exit is in the range of 0.02 to 0.05 and the multi-wavelength accuracy is within +/- 5°F (2.8°C).