On Fabry–Pérot Etalon-based Instruments. IV. Analytical Formulation of Telecentric Etalons

Abstract Fabry–Pérot etalons illuminated with collimated beams have been analytically characterized in detail since their invention. Meanwhile, most of the features located telecentric planes studied only numerically, despite wide use this configuration astrophysical instrumentation for decades. In work we present analytical expressions transmitted electric field and its derivatives that are valid placed slow beams, like ones commonly employed solar instruments. We to infer sensitivity variations optical thickness different reflectivities apertures incident beam, compare them case. This allows us estimate wavefront degradation produced by roughness errors on surfaces establish maximum allowed rms value cavity irregularities across footprint beam ensures diffraction-limited performance. also evaluate intrinsic these mounts, which is finite aperture must be added one defects. Finally, discuss differences performance etalon-based instruments generalize our formulation anisotropic etalons.