Provided is a method of designing an optical metrology system for measuring structures on a workpiece wherein the optical metrology system is configured to meet one or more signal criteria. The design of the optical metrology system is optimized by using collected signal data in comparison to the one or more signal criteria. In one embodiment, the optical metrology system is used for stand alone systems. In another embodiment, the optical metrology system is integrated with a fabrication cluster in semiconductor manufacturing.