EXPERIMENTAL-STUDY OF THE EFFECT OF SURFACE-DEFECTS ON THE FINESSE AND CONTRAST OF A FABRY-PEROT-INTERFEROMETER

While investigating the instrumental function of a Fabry-Perot interfe rometer [Appl. Opt. 34, 58 (1995)], we noticed some variation in fines se and contrast in the measured spectra when a 1.5-mm-diameter apertur e was used at various spots within the standard 8-mm aperture. By comp aring experimentally determined finesse versus contrast plots for many such spectra with calculated plots, we found spots on the plates that gave non-Airy-function line shapes over the entire order of interfere nce, unlike the Airy line shape we determined previously by using the entire 8-mm aperture. We have reviewed several models that describe th e effects of various types of surface defects, such as Gaussian-height distribution of roughness, curvature and tilt of plates, sinusoidal r oughness, and asymmetrical roughness on the finesse and contrast. Our experimental results can be accounted for if we assume that the reflec tivity is nonuniform over the Fabry-Perot plates and that there is som e reasonable contribution that is due to Gaussian roughness, curvature , or tilt. (C) 1996 Optical Society of America