The envelopes along the maxima and minima of the interference spectrum of a dielectric layer on a transparent substrate are often used to determine the optical constants of the layer. The envelopes are usually drawn by hand which can lead to significant calculation errors. An optimized algorithm is proposed for computer drawing of the two envelopes for transmission and reflection spectra with interference. The envelopes are drawn for several model cases and for an experimental spectrum.
"Computer drawing of the envelopes of spectra with interference", Proc. SPIE 1782, Thin Films for Optical Systems, (4 March 1993); doi: 10.1117/12.141047; https://doi.org/10.1117/12.141047