The vacuum level alignment approach may or may not hold due to details of the interface.
It is particularly important in the design of vacuum device components such as cathodes.
The value of the vacuum level depends on the surface chosen due to variations in work function.
[3] The phrase "vacuum level" also occurs often in texts on squeezed light where it refers to an unsqueezed measurement.
"[4] Note that the phrase "vacuum level" may also refer to a measurement of residual pressure in a vacuum system or a device that uses differential pressure such as a carburetor but this usage should be very clear from context.