Abstract: An apparatus for producing a preselected amount of light energy for use with photosensitive materials. The apparatus comprises a source for producing light; a light guide for delivering the light produced by the source to a work site; (c) a sensor means for detecting the intensity of the light produced by the source; and (d) a controller for determining the amount of light energy to be delivered to the photosensitive material at the work site. The apparatus includes a dimmer for controlling the intensity of light delivered to the work site and a shutter for controlling the exposure time for the work site. The dimmer and shutter are controlled by the controller so that a predetermined total quantity of light energy is delivered to the work site.