What does "metrological center" in this sentence mean?
The inverse cubic fit allows to determine the center of the dechirper with respect to the electron beam, which might differ from the metrological center.
metrology means the study of measures (and weights) so the metrological center would be the actual measured center, as opposed to the "center of the dechirper" (as for what that part means - you're on your own ;) )