Abstract

The simplest narrowband-pass filter is a thin-film Fabry-Perot cavity consisting of a quarterwave stack with a central layer being a multiple halfwave, as shown in Fig.1. Such cavities can have a series of pass bands if the reflectance bands are broad enough and the spacer layer is thick enough. Such pass bands are uniformly spaced in wavenumber. The need sometimes arises for a multi-line narrowband-pass filter in which the wavelengths of the pass bands are not uniformly spaced.

© 1992 Optical Society of America