CLOSED-FORM EXPRESSIONS TO FIT DATA OBTAINED WITH A MULTIPASS FABRY-PEROT-INTERFEROMETER

We have studied the effect of a multipass Fabry-Perot interferometer ( FP) on a scattering line. Here we describe a method that we applied to derive a closed-form expression for a line shape obtained with an ide al, multipass FP. The method reduces the convolution problem between t he multipass function and the scattering line to the corresponding sin gle-pass problem. We illustrate the method with a Lorentzian and a dam ped-harmonic-oscillator line passed through a single-, triple-, and qu intuple-pass FP. Furthermore we have applied the method to a study of the effect of the collecting pinhole on a sharp line obtained by multi passing. We show how we used these functions to fit the complete spect ra obtained with a single- and triple-pass FP.