Embodiments described herein provide a substrate processing apparatus that includes a vacuum chamber comprising a first dome and a second dome, a substrate support disposed inside the vacuum chamber between the first and second domes, a collimated energy source arranged in a compartmented housing and positioned proximate the second dome, wherein the second dome is between the collimated energy source and the substrate support. At least a portion of the second dome and the substrate support may be optically transparent to the collimated energy from the collimated energy source.