Sensing is the oldest of these, since cavemen had eyes, but fire for illumination came not much later and fire for smoke signal communication soon followed. In the modern world, optical sensing spans a range from microscopy to astronomical telescopy and includes still, cinematic and video photography, lidar, reflectometry, and a number of other applications. Optical sensing is increasingly dominated by electronic sensors and digital processing. Despite the long history of smoke signals, lighthouses, lanterns and signal lights, optical communications has bloomed as an industry only in the past 20 years. The key to this development has been the explosion in demand for data transmission, the development of astonishingly low loss optical fiber and the development of semiconductor laser sources and detectors.
Illumination has a longer history as a major industry than either sensing or communications.
Illumination today includes the range from flashlights to laser tools for surgery. In view of the greater potential for research and engineering at the higher tech end of the scale, modern engineering courses tend to emphasize lasers over lightbulbs. There are other optical technologies which are difficult to classify in these three areas, for example, optical data storage mixes sensing, communications and illumination. This course covers sensing applications of optical fields. In the UIUC ECE department ECE 371 GP covers communications applications and ECE 355 covers lasers.