Patent ID: 7153616

Claim:
A maskless lithography system, comprising: a spatial light modulator that includes a plurality of spatial light modulator cells; a reference reticle having at least one reference feature, the reference reticle located in a plane with the spatial light modulator proximate to one of the plurality of spatial light modulator cells; a pattern rasterizer that applies a signal to the spatial light modulator to form a die pattern that includes the at least one reference feature; an illumination source that emits illumination energy to illuminate the spatial light modulator and the reference reticle; projection optics, having a pupil, that form a die image with illumination energy entering the pupil from the spatial light modulator and a reference image with illumination energy entering the pupil from the reference reticle; and a reference reticle postioner that positions the reference reticle to direct incident illumination energy from the illumination source away from the pupil of the projection optics.