Effect of the Electrode Bore Angle on the Two-Electrode Electrostatic Immersion Lens Design

This paper describes the influence of the front electrode bore angle on the electron optical performance of the two-electrode electrostatic immersion lens. The electrode bore shape is the most important geometrical parameter in any electron optical device. Accordingly, a design of an electrostatic immersion lens is presented and its electron optical properties are calculated and compared for different values of bore angle of the electrode facing the incident electron beam. It has been found that the electrode bore angle has a slight effect on the electron optical properties of the electrostatic lens design. Moreover, the best compromise aberration coefficients are obtained at an angle equal to (16°)