Abstract: Apparatus for making a plastic lens is described. More particularly, an apparatus for applying alternating periods of ultraviolet light to a lens forming composition is described. The lens forming composition is cured while the rate of heat generation and/or dissipation is controlled via manipulation of the duration of the ultraviolet light or the cooling in the curing chamber. The ultraviolet light is preferably directed toward the lens forming composition which is disposed in a mold cavity formed by two mold members. The ultraviolet light may be directed in pulses or continuously.