So far, the column we have designed will just focus the electron beam into a spot on the sample. This is fine for welding or if we wanted the beam to pass through the sample as in a TEM, but for an SEM to work, we need the beam to scan.

By placing sets of plates around the beam and varying the potential between them, the electron beam can be deflected. If these plates are attached to a scan generator, the beam can be made to scan lines across the sample similar to the way a television tube scans.

But if this scan generator is not only controlling the scan coils, but is also controlling the beam of a CRT, the image formed on the CRT will be synched to the electron beam scanning the sample

5                                                                NEXT