Arc light spectrum recombined with concave mirror on lucite rod.

Arc light spectrum recombined with concave mirror on lucite rod. An optical bench is arranged with an adjustable slit and prism so that the spectrum from the prism fills a large concave mirror. A translucent lucite rod is placed at the focus of the mirror in full view of the class. The optical system is arranged so that the spectrum is focused on the mirror. Light shields are used to block out portions of the spectrum that fall on the concave mirror. Thus, only desired colors are directed to the lucite rod. If the entire spectrum is brought to focus on the rod, the result is a spot of white light.