Ein beitrag zur grundlegung einer allgemeinen, ebenen strahlenoptik und neue erkenntnisse für die konstruktion massenspektrometrischer instrumente

Abstract

The known formulae for calculation of the second-order spherical aberration of homogeneous magnetic sector-field systems are complicated. Optical quantities are not used as parameters or variables, but geometric quantities of the sector-field system occur frequently in these formulae. In order to get a deeper understanding of the magnetic sector-field system and an overall appreciation of this type of instrument, in which ion currents are analyzed for momenta or energies by means of static fields, a general system of asymmetric ray optics is developed. This system is independent of the physical type of ray involved and of the configuration and quality of the refractive medium. Optical quantities only enter into the calculation, these being constant for a given caustic curve and refraction, together with derivatives of these constants with respect to the image beam angle, these being also constants. A formula for spherical aberration and conditions for the focusing of beams up to third order inclusive are stated; conditions for aplanatism are also noted. The usefullness of an abstract type of ray optics which has been used previously for the special case of rotation-symmetric caustics, is discussed briefly as a principle for the design of light-optical instruments. Finally the magnetic sector-field system with only one straight-line entrance limitation is demonstrated as an example of a physical embodiment; using magnification as the independent variable, all possible beams focusing are stated together with the associated determinants of the systems.