ABSTRACT

Looking back over the past 1000 years, we notice that infrared (IR) radiation itself was unknown until

200 years ago when Herschel’s experiment with a thermometer was first reported. He built a crude

monochromator that used a thermometer as a detector so that he could measure the distribution of

energy in sunlight [1]. Following the works of Kirchhoff, Stefan, Boltzmann, Wien and Rayleigh,

Max Planck culminated the effort with the well-known Planck’s law.