This paper will describe the development, qualification, monitoring, and integration into a production environment of the world's first fully programmable illuminator for optical lithography. FlexRay™, a programmable illuminator based on a MEMs multi-mirror array that was developed for TWINSCAN XT:19x0i and TWINSCAN NXT series ASML immersion scanners, was first installed in January 2010 at Albany Nanotech, with subsequent tools installed in IBM's East Fishkill Manufacturing facility. After a brief overview of the concept and benefits of FlexRay, this paper will provide a comprehensive assessment of its reliability and imaging performance. A CD-based pupil qualification (CDPQ) procedure will be introduced and shown to be an efficient and effective way to monitor pupil performance. Various CDPQ and in-resist measurement results will be described, offering convincing evidence that FlexRay reliably generates high-quality pupils and is well suited for high volume manufacturing at lithography's leading edge. © 2011 SPIE.