Study of Effect the Iron arm Thickness and the Distance Between Pole Pieces on the Optical Performance of Symmetrical Double Pole Piece Magnetic lens

In this paper, a symmetrical double pole piece magnetic lens has been designed as an objective lens to be used for electron microscope. Three different thickness (t= 4, 8, 12) mm of iron arm were chosen at a constant distance of (S=2 mm) between pole piece of lens. The results show that at (t= 8 mm) of iron arm thickness, a better optical properties of lens; magnetics flux density (Bz), focal length (fo), spherical (Cs) and chromatic (Cc) aberration were achieved. Then, the effect of various value of the distance (S= 2,4,6) mm between the pole piece at a chosen thickness of iron arm was investigated. The highest magnetic flux density and low chromatic and spherical aberration coefficient were achieved at iron arm thickness and the distance between the pole piece (t= 8 mm, S= 2 mm) respectively. The optical properties of the lens as a function of accelerated voltage in the range of (Vr = 1 to 9) Volt was studied at a constant lens excitation of (NI = 2 kA-t). The distribution of magnetic flux at different excitations values was calculated.

Keywords: Objective magnetic lens, Iron arm thickness, Distance between pole piece, optical performance, symmetrical double pole piece lens

In this paper, a symmetrical double pole piece magnetic lens has been designed as an objective lens to be used for electron microscope. Three different thickness (t= 4, 8, 12) mm of iron arm were chosen at a constant distance of (S=2 mm) between pole piece of lens. The results show that at (t= 8 mm) of iron arm thickness, a better optical properties of lens; magnetics flux density (Bz), focal length (fo), spherical (Cs) and chromatic (Cc) aberration were achieved. Then, the effect of various value of the distance (S= 2,4,6) mm between the pole piece at a chosen thickness of iron arm was investigated. The highest magnetic flux density and low chromatic and spherical aberration coefficient were achieved at iron arm thickness and the distance between the pole piece (t= 8 mm, S= 2 mm) respectively. The optical properties of the lens as a function of accelerated voltage in the range of (Vr = 1 to 9) Volt was studied at a constant lens excitation of (NI = 2 kA-t). The distribution of magnetic flux at different excitations values was calculated.

Anahtar Kelimeler: Objective magnetic lens, Iron arm thickness, Distance between pole piece, optical performance, symmetrical double pole piece lens

Page Range: 57-66

Hussein, M. A. & Aesa, A. A. (2022). Study of Effect the Iron arm Thickness and the Distance Between Pole Pieces on the Optical Performance of Symmetrical Double Pole Piece Magnetic lens. Journal of Current Researches on Educational Studies, 12 (2), 57-66.