Properties of Fabry-Perot interferential filters illuminated in oblique incidence

The properties of dielectric filters of Fabry-Perot type can be calculated on the basis of an approximate matrix method yielding relatively simple expressions. These relations make it possible to determine the wavelength lambda M for which the filter shows a maximum in the transmission for the two directions of polarization. This includes the calculation of the transmissions T( Lambda ) for the neighbouring wavelengths of Lambda M and of the filter passbands, whether it is illuminated by a natural or polarized source. Multilayer structures with some optical qualities chosen beforehand can then be calculated in terms of incidence angle theta 0.