the mask with a nonplanar surface of the workpiece. The mask in these embodiments may correspond to the nonplanar surface.
The present invention also includes a photolithography apparatus for forming an offset pattern in a tubular workpiece and a photolithographic method of forming a radially spaced offset pattern on a three dimensional workpiece. The photolithography apparatus in some embodiments comprises a stage having a hemicylindrical substrate channel adapted to receive a tubular workpiece, a hemicylindrical mask defining at least one aperture, a first stop associated with the stage and adapted to position the workpiece in a first position relative to the mask, a second stop associated with the stage and adapted to position the workpiece in a second position relative to the mask, and an exposing light source adaptedto illuminate the tubular workpiece through the at least one aperture. The photolithographic method in some embodiments comprises the acts of placing a workpiece on a stage, jogging the workpiece against a first stop, exposing a first portion of the photo-sensitive coating through a mask, rotating the workpiece, jogging the workpiece against a second stop, and exposing a second portion of the photo-sensitive coating though the mask. The workpiece in this method has a photo-sensitive coating.
An advantage of the present invention is that it may be used to produce a selected pattern of holes on or in a workpiece having a small cross-sectional area or diameter more cost efficiently than machining. Another advantage of the process of the present invention is that it is well suited for producing