Investigation on a short magnetic lens spectrometer

Abstract

In the course of an attempt to find reversible relations between the parameters describing the trajectory of an electron in a short magnetic lens spectrometer, it was found that the magnetic lens can be surprisingly well represented by a thick converging type optical lens which satisfies Newton's laws for the conjugate planes and the tangent relation far outside the paraxial range where the lens power calculated by the paraxial method can be in error by as much as 50%. Expressions have been obtained for the focal length as a function of the object angle and momentum of the electron. Various other properties of the lens spectrometer have been investigated. In particular, the use of a continuous baffle system to improve the resolution and line-shape for an extended source has been studied by an easy and accurate method.