Abstract
A theoretical design has previously been proposed for a low-aberration magnetic deflection system.1 This has now been translated into practice. Specially shaped interleaved deflection coils have been constructed that give rise to low values of all the aberration coefficients except for distortion and field curvature. The latter aberration is corrected electrically. Since the sole effect of distortion is to destroy the linearity between coil excitation and beam deflection, no correction for this aberration has been incorporated at present. A combined electrical and mechanical centering procedure has been developed and implemented. The deflection system has been tested and found to increase the diameter of an on-axis spot by a maximum of 1.2 μm over a 3×3-mm working field at an angular aperture of 8 mrad. This compares well with the theoretically predicted value of 1.3 μm. The spot diameter has been taken as the 1% to 99% rise distance of the transmitted beam current as the spot was scanned across an edge. The theoretical work has been extended to show that under certain conditions it is, in principle, possible to eliminate the noncorrectable aberrations completely.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
