HISTORY OF INFRARED
William Herschel ‘discovered’ infrared heat during the 19th century. He held a prism up to light from the sun and observed the refraction of light in a prism. While he was conducting this experiment he found a section of heat directly below red on the spectrum as measured by a thermometer. He originally called these rays “Calorific Rays” and proceeded to publish his results with the Royal Society of London in 1800.
A timeline of advancements in Infrared Science