GB646440A - Improvements in or relating to electron microscopes - Google Patents

Abstract

646,440. Electron microscopes. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. Aug. 27, 1947, No. 23675. Convention date, Aug. 30, 1946. [Class 39 (i)] A removable object-holder 7, Fig. 1, is mounted through the stopper 6 of a tube 2, which is closed at the other end 10 and is rotatably mounted in the wall 1 of the microscope so that the tube apertures 9 for the electron beam can be closed. In the form shown in Fig. 1, the beam apertures 9 in the tube can be sealed by a member 11 which is supported by the metal tube 1 and has beam apertures 12. The microscope may be continuously evacuated. In a further form, the amount of air which can leak subsequently into the microscope following the exchange of objects 25, Fig. 2, is minimized by using an object holder 18 which is a sliding fit in the rotatable tube 13. The beam apertures in the tube can be closed, upon rotation, by rubber rollers 27 mounted on spindles 29, which are pressed towards the tube by springs 31. To prevent wearing of the rollers when not sealing the apertures, the spindles sink into recesses in the tube so that the rollers move inwardly when the beam apertures are to be closed. Alternatively bosses on the tube 13 may lift the spindles. The end 17 of the object holder 18 passes through a stuffing box 16 and is secured within a knob 19. A slotted rim 22 forms with projections 20 a bayonet joint. The knob 19 houses a pin 23 on the tube 13 so that removal of the knob, together with the object holder, can be effected only after rotation of the knob and the tube to close the beam apertures. Adjustment of the object holder relative to the tube 13 is permitted by limited movement of the pin 23 in the knob 19. An indicating projection 36 may be provided on the knob.