Image transfer through a Fabry-Perot interferometer

An experimental method for determining the transfer function and accompanying cutoff frequency of a Fabry-Perot interferometer (FPI) is described and a set of experimental results is presented. It is shown that upon passage through the FPI, the level of image distortion decreases with a decrease in cavity length (resulting in an increase in Fresnel number) when the FPI finesse is held constant. This phenomenon is in agreement with the theoretical prediction.