GB1128107A - Scanning electron microscope - Google Patents

Abstract

1,128,107. Cathode ray tubes. HITACHI Ltd. 15 June, 1966 [23 June, 1965], No. 26722/66. Heading H1D. In a scanning electron microscope, the secondary or reflected electrons emitted from the point of impact of the primary beam on the specimen are focused by a uniform magnetic field extending along the path of the incident beam from adjacent the final magnetic focusing lens of the microscope, and are thereafter deflected sideways from the path of the incident beam to a detector, either by a magnetic or by an electro-static field, whereby the final lens of the microscope may be disposed close to the specimen surface. The incident beam 38 passes through an aperture 37 in the curved solenoid 35, which extends into the focusing lens 31, 32, 34, and thereafter through an aperture 41 on to a specimen 39, both of which are adjustable from outside the tube. The emitted electrons are focused and deflected by solenoid 35, and are accelerated by grids 42 and 45 on to the detector 36, the signal from which modulates the intensity of a synchronously scanned cathode ray tube. In another embodiment (Fig. 5, not shown), the continuous curved solenoid 35 is replaced by a succession of spaced, angularly displaced short coils. In a further embodiment (Fig. 7, not shown), in which a straight solenoid (58) extends most of the way through the magnetic lens, the sideways deflection of the secondary electron beam is achieved by the use of a pair of inclined electrodes (60, 61) which are apertured to provide passage for the incident beam.