Effect of Changing Distance between Poles on Optical Properties of Gemini Lens

Abstract

Modern and advanced software was used to reach quick results of the optical properties of the proposed models of Gemini lenses. Four basic designs of the objective magnetic lens were employed in scanning electron microscope, according to the design site and the required analysis ability, the four models were designed equal in geometric dimensions and file size, and the results showed that the Gemini objective lens (S3) achieved the best results because it obtained the lowest values for the final effective probe diameter and the focal length (f=4.76 mm) that corresponds to the highest value for analysis. At a constant value of the excitation (NI = 1000 A-t), it also had the lowest coefficients of spherical and chromatic aberration (Cs=4.14 mm) and (Cc=3.63 mm).