Laboratory Apparatus: Optics Around 1900 the classic science of optics caused a furore. I fit earlier been established that light was a wave phenomenon, matters now turned out to be much more complicated. Light was dualistic: mostly it disguised itself as waves, but sometimes as particles. Those waves or particles, moreover, possessed an unpredicted, specific energy. They were called quanta. This revolution, the greatest since Newton, was an intellectual one. In the laboratory old friends like lenses and slits still worked perfectly well.