Abstract: A light regulation system is provided wherein the light output of a second, fluorescent lamp fixture is regulated in accordance with the light output of a first or preceeding fluorescent lamp fixture. Each fixture includes a lamp or lamps, a ballast or ballasts and a control or regulating device which controls the ballasting of the lamp(s) of the fixture and hence the light output thereof. The system provides for monitoring the light output of the master fixture and optically coupling a corresponding signal to a photocell in the control device of the following fixture so as to control the output of the lamp(s) of the following fixture. Additional fixtures can be optically coupled in like manner to either the master or a follower fixture to provide additional controlled following fixtures.