GB1340209A - Electron microscope - Google Patents

Abstract

1340209 Electron microscopes NIHON DENSHI KK 23 Dec 1970 [25 Dec 1969] 61282/70 Heading H1D In an electron microscope provided with two sets of deflecting means for deflecting the beam off the axis and back again in order to vary the angle of incidence of the beam on the specimen to observe a dark field image and a diffraction pattern, the point of incidence may vary as the angle is varied due to the deflecting coils in one set not being positioned accurately orthogonal to each other and parallel to those of the other set. This is obviated by feeding each coil with at least two uni-directional current components which are independently adjustable. In one example the coils deflecting the beam off the axis are each fed with three components for adjusting the deflection, for compensating for positional errors, and for aligning the beam, whilst the coils returning the beam to the axis are supplied with two components. The separate components may be derived from potentiometers which may be manually adjustable, and the controls of different coils may be coupled together to effect dependent adjustments in predetermined manner. The outputs of the potentiometers may be fed through individual resistors to the input of a summing amplifier feeding the coil directly (Fig. 2, not shown) or through a transistor output circuit (Fig. 3, not shown). Alternatively the potentiometers may be connected to individual amplifiers, the outputs of which are summed (Figs. 4 and 5, not shown).