Nozomu Morito

On the Measurement of Isotope Abundance of Lithium with Mass Spectrometer

The values of the isotope abundance ratio Li/sup 7/Li/sup 6/ obtained were 12.48 plus or minus 0.05 and 13.69 plus or minus 0.05 for two samples of lithium chloride. (W.D.M.)

Multiple Dispersion Mass Spectrometer with Ion Mirror

Ion mirrors are introduced to realize multiple dispersion in a single magnetic field of a mass spectrometer. An ion source, two ion mirrors, and an ion collector are suitably placed around a magnetic field. The ion mirrors can also be used as ion collectors. If the polarity of the accelerating voltage is reversed, negative ions can be analyzed. (C.E.S.)

On the Chromatic Field Aberration of the Magnetic Electron Lens in the Electron Microscope

The chromatic field aberration of the magnetic lens in the electron microscope is theoretically studied.Good results are obtained for the coefficient of the chromatic difference in magnification of the objective, taking into account the inclination of the principal illuminating rays. The same coefficient of the intermediate lens increases rapidly as the magnification is reduced by the intermediate lens. The calculated results agree well with experimental results.Calculated results are given for the coefficients of chromatic difference in rotation of all lenses as well as for the coefficient of chromatic difference in magnification of the projection lens.

Linsen und Ablenksysteme

Die rechnerische Untersuchung eines elektronenoptischen Systems erfordert in der Regel so genaue Werte der Feldverteilung, wie sie nur mit modernen elektronischen Digitalmaschinen erhalten werden konnen. Die Erfahrung zeigt aber, das die Losung der Potentialgleichung nach dem Maschenverfahren mit programmgesteuerten universalen elektronischen Maschinen recht zeitraubend (Programmieren) und relativ kostspielig (lange Losungszeit) ist. Mussen laufend viele Felder berechnet werden, so lohnt es sich, eine relativ billige Spezialanlage zur Losung der Potentialgleichung zu bauen. Sie mus sich durch geringen Arbeitsaufwand bei der Einfuhrung der Ausgangsdaten und durch grose Genauigkeit auszeichnen und so die Vorteile eines Widerstandsnetzes und einer digitalen Rechenmaschine in sich vereinigen. Dies wird erzielt durch Serienschaltung eines Netzgerates, das die Potentialgleichung in erster Naherung lost, mit einer einfachen, spezialisierten Digitalmaschine, die den Approximationsfehler jener Losung reduziert.

The development of the lens system in the Hitachi electron microscope

Astigmatism was already mentioned in Ardenne’s famous book (1), but the astigmatism described therein was one of the Seidel’s aberrations of the third order and a field aberration. Axial astigmatism was more important, though it had not been well known at that time. We usually took underfocused micrographs, in which the astigmatic image defect was vague.