Who were some of the innovators of lighting design in history?

Some innovators of lighting design include Henry Irving in England, who created special effects and darkened the audience to give full focus to the stage. He put up black masking to prevent light from spilling into unwanted areas. David Belasco built a light laboratory in his theatre in New York, where he and Louis Hartman, an electrician, experimented with new techniques and invented devices, such as the top hat to control the spill of light. Munroe Pevear contributed to lighting design with advances in lighting color theory. Adolphe Appia theorized that light could unify the actor, the stage set, and the floor of the playing area, a concept that has influenced lighting design ever since.