Control of parasitic aberrations in multipole optics

Area of Science:

• Charged particle optics
• Aberration correction

Background:

• Third-order aberration correctors are crucial for high-resolution imaging.
• Parasitic effects often limit corrector performance.
• Accurate aberration measurement is essential for correction.

Purpose of the Study:

• To develop a method for optimizing the fourth-order setup of quadrupole-octupole aberration correctors.
• To synthesize pure controls for aberrations up to fourth order.

Main Methods:

• Utilizing accurate aberration measurements up to fifth order.
• Employing stimulus/response experiments.
• Synthesizing pure controls for individual aberrations.

Main Results:

• A method to find the optimal fourth-order setup for aberration correctors.
• Successful synthesis of controls for aberrations caused by parasitic effects.
• Correction of aberrations including symmetry violations and misalignments.

Conclusions:

• The described method enables precise aberration control up to fourth order.
• This approach effectively addresses aberrations arising from various parasitic effects.
• Optimized aberration correctors enhance imaging performance.