Pre-measurement
Vacuum measurement

The table at 1 shows the importance of the means used to produce the vacuum, depending on the range to be achieved. While we immediately think of the pumping required, we must not neglect the enclosure (or installation in general) that will confine the vacuum, which is just as important. The division into different vacuum domains in table 1 reflects the increasing difficulty of moving from one vacuum domain to the next, in terms of the technical nature of the implementation and the cost of equipment and instrumentation.

As far as measurement...