At the present time, there are no commercial proton beam writers available: The first working prototype has been constructed in the Centre for Ion Beam Applications, Physics Dept, National University of Singapore.
The lens system used in this prototype is the Oxford Microbeams lens system (OM52) operating in a high excitation compact triplet configuration. This lens system operates at an object distance of 7 m and a reduced image distance of 70 mm resulting in enhanced system demagnifications (228 × 60 in the X and Y directions respectively). This lens system is capable of focusing a MeV proton beam down to 40 × 40 nm spot sizes, due to superior imaging properties and low aberrations.
References
- Oxford Microbeams: www.microbeams.co.uk