English: The physical meaning of the Airy finesse
of a Fabry-Pérot resonator.
[1] When scanning the Fabry-Pérot length (or the angle of incident light), Airy distributions (colored solid lines) are created by signals at individual frequencies. The experimental result of the measurement is the sum of the individual Airy distributions (black dashed line). If the signals occur at frequencies
, where
is an integer starting at
, the Airy distributions at adjacent frequencies are separated from each other by the linewidth
, thereby fulfilling the Taylor criterion for the spectroscopic resolution of two adjacent peaks. The maximum number of signals that can be resolved is
. Since in this specific example the reflectivities
have been chosen such that
is an integer, the signal for
at the frequency
coincides with the signal for
at
. In this example, a maximum of
peaks can be resolved when applying the Taylor criterion.