Methods are described for correcting parabolic errors in Fabry-Perot interferometers using evaporated films and an appropriate shutter. Errors of λ/50 can be readily reduced to less than λ/400 over 54-mm apertures (λ ≈ 550 nm).
R. P. Netterfield and J. V. Ramsay, "Correction of Parabolic Errors in Fabry-Perot Interferometers," Appl. Opt. 13, 2685-2688 (1974)