A High-Vacuum Controller for an Eventual Electron Microscope
[Chris Doble] has high ambitions: he’s making his own scanning-electron microscope, and as the first step he’s built a high-vacuum system. This required its own controller to manage the various electronics involved in the system, which he’s documented and open-sourced . The vacuum system itself starts with a rotary-vane roughing pump, which can bring a chamber down from atmospheric pressure to about 10 -3 millibar. This is still too high a pressure, so the second stage is a turbomolecular high-vacuum pump, which can operate from 18 millibar down to 10 -7 millibar. To protect the turbomolecular pump in case the roughing pump suddenly stops, it includes an anti-suckback valve. Connected to these pumps is a pressure gauge which uses a pair of sensors to sense the entire pressure range. All this setup worked well, but the turbomolecular pump and the pressure sensor each used their own interfaces, while [Chris] wanted a single interface for the eventual microscope. [Chris] therefore d...