PARTICLE-OPTICAL CORRECTOR WHICH IS FREE FROM AXIAL ABERRATION OF SIXTH ORDER AND ELECTRON MICROSCOPE WITH CORRECTOR

• Main Author: UHLEMANN STEPHAN
• Format: Patent
• Language: English; Japanese
• Published: 01.03.2021
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS; ELECTRICITY

To provide an electron microscope with a corrector that is free from axial aberrations of sixth order.SOLUTION: A corrector 5 includes: a central multipole element 2 of length L for generating a hexapole field ΨHP2 in a symmetry plane 6; identical two outer multipole elements 1, 3 of length L' for generating hexapole fields ΨHP1, ΨHP3 having identical strengths; and two round lens doublets 7, 8 including round lenses 7', 7'', 8', 8''. The strength of the hexapole fields and length of poles of each of the central multipole element 2 and the outer multipole elements 1, 3, and the overall corrector 5 are selected such that a threefold axial astigmatism A2, a sixfold axial astigmatism A5, an axial three-lobed aberration of fourth order (D4) and an axial three-lobed aberration of sixth order (D6) varnish.SELECTED DRAWING: Figure 1 【課題】６次の軸上収差のない補正器を備えた電子顕微鏡を提供する。【解決手段】補正器５は、対称面６に６重極場ΨＨＰ２を生成する長さＬの中央多重極素子２と、同一の強さの６重極場ΨＨＰ１、ΨＨＰ３を生成する長さＬ'の同一の２つの外側多重極素子１、３と、円形レンズ７'、７''、８'、８''を備えた２つの円形レンズダブレット７、８とを有し、中央多極子２と外側多極子１、３のそれぞれの６重極場の強さや極子の長さ、および、補正器５全体は、３回軸上非点収差Ａ２、６回軸上非点収差Ａ５、４次の軸上スリーローブ収差（Ｄ４）、および、６次の軸上スリーローブ収差（Ｄ６）が消滅するように選択される。【選択図】図１