Some turning-points in infra-red history

The address covers significant advances from the earliest work, by William Herschel, to the development of detectors in the past decade which bridge the gap between light waves and radio waves. The theoretical discussions of the nineteenth and early twentieth centuries, which led to an understanding of radiation, are followed by descriptions of applications in World Wars I and II and brief mention is made of thermography, the invention of laser generators and infra-red meteorology.