A type of filter that uses the effect of interference of light to limit the wavelengths that pass through it. Ordinary filters are coloured, but interference filters consist of very thin multiple layers of alternating high and low refractive index (e.g. zirconium dioxide, magnesium fluoride) coated on glass. The incident light reflects backwards and forwards between the layers, thereby interfering with itself. By appropriate choice of thicknesses, the range of wavelengths that the filter transmits (the passband) can be adjusted. Nebula filters and the anti-reflection coatings on camera and binocular lenses are simple interference filters.
Subjects: Astronomy and Astrophysics — Chemistry.