This article is an update of the original article
filters, optical
in which the theory of optical filters, the basic physical phenomena, and several types of filters were described.
Starting from these concepts, a number of examples of filter applications are reported, showing the variety of wavelength ranges and filter dimensions that could be required.
Application fields such as automobiles and buildings, lighting and displays, laser facilities, and space and security are considered, as representative of different conditions of use. Traditional and more recent types of filters are described, taking into account the development of less conventional materials and structures.