A device and method to prepare a stepper to form semiconductor structure lines by using a calibration reticle to determine optimum numerical aperture and partial coherence values for the stepper. The calibration reticle includes a light-transmissive substrate having a plurality of patterns disposed thereon, each of the plurality of patterns including a series of structures of a constant size spaced an equal distance from one another and having a predetermined pitch intended to mimic a pitch value of a semiconductor structure reticle. The method includes positioning the calibration reticle on a stepper and optimizing the performance characteristics (e.g., the partial coherence value and the numerical aperture value) of the stepper using one of the patterns of the calibration reticle corresponding to a predetermined pitch of a semiconductor structure reticle.