Patent ID: 8445862

Claim:
A multi-axis magnetic immersion objective lens, comprising: a pair of parallel magnetic conductor plates with a plurality of through round holes in pairs therein, the pair of parallel magnetic conductor plates including an upper plate and a lower plate, for each paired through round holes, an upper through round hole in the upper plate aligned with a corresponding lower through round hole in the lower plate; a plurality of magnetic rings in pairs inside and aligned with the plurality of through round holes with a plurality of first radial gaps in pairs respectively, wherein for each pair of magnetic rings in the pair of parallel magnetic conductor plates respectively, an upper magnetic ring is aligned with and extends downward through inside a corresponding lower magnetic ring with a second radial gap, wherein each paired first radial gaps include a first upper radial gap between inner sidewall of the upper through round hole and outer sidewall of the upper magnetic ring, and a first lower radial gap between inner sidewall of the lower through round hole and outer sidewall of the lower magnetic ring, thereby forming a plurality of magnetic sub-lens modules for focusing a plurality of charged particle beams respectively, wherein for each sub-lens module, the upper magnetic ring functions as an inner pole-piece and the corresponding lower magnetic ring functions as an outer pole-piece; and a common excitation coil located between the pair of parallel magnetic conductor plates for providing magnetic flux to the plurality of magnetic sub-lens modules.