Max Planck was a German physicist and is considered to be the founder of the quantum theory, and thus one of the most important physicists of the twentieth century.
The complete history of infrared thermography starting with William Herschel, whom is given credit for conceiving the concept of an infrared radiation in the early 19th century.
Gustav Robert Kirchhoff was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects. He even coined the term “black body” radiation in 1862.
Macedonio Melloni, a physicist from Italy, was renowned for giving testament to radiant heat that carried those physical properties that had with the light.
Willoughby Smith was a British electrical engineer who unearthed the photoconductivity of the component selenium.