Embodiments described herein generally relate to apparatus for heating substrates. The apparatus generally include a process chamber having a substrate support therein. A plurality of lamps is positioned to provide radiant energy through an optically transparent dome to a substrate positioned on the substrate support. A light focusing assembly is positioned within the chamber to influence heating and temperature distribution on the substrate and to facilitate formation of a film on a substrate having uniform properties, such as density. The light focusing assembly can include one or more reflectors, light pipes, or refractive lenses.