The Development of Thermal Imaging Systems

Abstract

The first scientific study of thermal radiation began with the optical experiments of della Porta at the end of the 16th century. His experiments were repeated and extended up to the time of Rumford and Davy in the early 19th century, and these experiments led to a considerable knowledge of the characteristics of thermal radiation. This culminated with the work of Pictet and his colleagues de Saussure and Prevost who in Geneva by 1790 had established the concept that all bodies radiate heat, the higher the temperature the greater the radiation such that when two bodies at different temperatures are within sight of each other the hotter will supply heat to the colder until they reach the same temperature. This result, known as Prevost’s Theory of Exchanges was the starting point from which the modern physical theory of thermal radiation was developed in the 19th century, eventually leading to Planck’s radiation formula at the beginning of the present century.