Recent developments in metal‐sealed gate valves

The Early Development of the Scanning Electron Microscope

“…These were in ultra-high vacuum technology that enabled vacuum systems that were capable of reaching 10 −8 Pa or less to be easily put together using standard components: in particular, the Conflat flange (Wheeler & Carlson 1962), all-metal vacuum valves (Wheeler 1976), and the development of the sputter-ion pump, starting with Hall (1958). Therefore, just about the time that the SEM was becoming generally used with the Stereoscan and the JEOL JSM-1, it was becoming possible to realize Zworykin's (1942) initial concept of a SEM with a low-voltage scanning beam (800V), a cold field-emission gun cathode, secondary emission contrast from a polished sample, and a fast scan.…”