
The human eye "cannot" see in the infrared spectrum.
The infrared spectrum is nothing new. It has been around since the beginning of time. However, Sir William Herschel is the person actually credited with discovering it. Today, Infrared Thermography, a part of the science of infrared imaging and analysis has risen to new heights.
Infrared
comes
from the Latin word
infra, which
means "below". Red is the color of the longest wavelengths of
visible light. Since
Infrared light has a longer
wavelength (a lower frequency) than that of red light which is visible to
the human eye, thus the meaning...below
red.

Today there are many application uses for Infrared. Infrared is used in such fields as Astronomy, Medical, Military, Surveillance, Animal Health, Building/Home & Industrial Inspections (thermal efficiency), Electrical, Marine, Weather Forecasting, Search and Rescue, Fire Fighting and the list goes on. There are really thousands of applications where Infrared can be used. Seattle Infrared works within an area of Forward-looking infrared ( FLIR ) which is from 8-14 µm. You can not see radiated temperatures in that range with the human eye even though you can feel that radiation with the end of your finger. By using a specially designed camera, that area of radiated heat can be seen and measured from a distance. That is a huge safety factor as well as the best and most cost efficient way to inspect key components without having to shut down operations.