Catadioptric lens barrel structure having a plurality of split lens barrels and a support structure supporting the split lens barrels

1. Field of the Invention A catadioptric lens barrel structure for a projection exposure apparatus includes first and second lens barrels, each having an optical axis that is parallel to the other, and a transverse lens barrel connecting the first lens barrel to the second lens barrel. The catadioptric lens barrel structure may be used in semiconductor fabrication by placing a reticle in front of the entrance of the first lens barrels and a wafer in front of the exit of the second lens barrel. The first and second lens barrels comprise a plurality of sub-barrels serially aligned along the corresponding optical axis. There is physical separation between each sub-barrel in the series to isolate each sub-barrel from thermal and vibrational effects propagated by the other sub-barrels in the series. A support structure is provided to support each of the plurality of sub-barrels and is made of a material having a low coefficient of thermal expansion. The support structure comprises a plurality of support platforms.