The history of near-infrared spectroscopy began in 1800 with the discovery of infrared light by British physicist F. W. Herschel (1739–1822). Herschel, an accomplished astronomer, discovered Uranus using a reflecting telescope with mirrors he ground himself. He has made more than 400 telescopes for astronomical enthusiasts to use. Some of them complained that observing stars through telescopes would burn their eyes. This prompted Herschel to design an experiment to study the thermal effect of the sun’s light. He used the prism-splitting phenomenon discovered by Newton in 1666 to disperse the sun’s light into different colors of light and then used a thermometer to measure the heat of different light colors one by one. In the event, he found that there was still a greater intensity of heat outside the red light. He concluded that there was still an invisible light outside the red light, which he called “Infra-red” in Latin. Because his prism was made of glass, which absorbs mid-infrared radiation, the band he actually detected was in the near-infrared (NIR) region [1].