The simplest form of an optical etalon is a transparent plate with parallel surfaces. Such a structure forms a resonator, and the transmittance and reflectance vary with the thickness of etalon. Beside the simplest structure, etalons with other configurations, with e.g. non-parallel surfaces and curved surfaces, are designed and used for different applications. With the non-sequential field tracing technique, several configurations of etalons are analyzed, and the differences in the output interference fringes are investigated.
