An apparatus for changing an aggregate intensity of a light within an
illumination field of a photolithography system having a blade structure
and a first actuator. The blade structure is configured to be positioned
along an optical path of the photolithography system between an
illumination system and a reticle stage so that, when the illumination
system provides the light having the illumination field, the blade
structure is substantially at a center of the illumination field and a
first portion of the light within the illumination field impinges upon
the blade structure. The first actuator is coupled between a first
portion of the blade structure and a frame of the photolithography system
and is configured to move at least the first portion of the blade
structure in a first direction so that a second portion of the light
within the illumination field impinges upon the blade structure.