A process for the adjustment of the pole shoes of a magnetic objective lens of a grid - korpuskular beam microscope

摘要

The raster electron microscope with a television monitor has a magnetic object lens whose both pole shoes are adjustable for reducing the parallel offset of their bore axes. With a constant object position and respective focussing current of the object lens, a detail of the object, whose image point is located in the centre of the monitor screen, is determined. Then the energising of the object lens is reversed and the new image point of this detail is determined on the monitor screen. Subsequently a new image point is approximated to the centre of the monitor screen by mechanical adjusting of one pole shoe, or by mutual adjusting of both pole shoes. Preferably a third characteristic image point is detected, forming with the two previous ones a specified triangle.