Excitation filter

An excitation filter is a high quality optical-glass filter commonly used in fluorescence microscopy and spectroscopic applications for selection of the excitation wavelength of light from a light source. Most excitation filters select light of relatively short wavelengths from an excitation light source (as light with shorter wavelengths have higher energy, according to the Planck equation E = hc / l). The excitation filters used may come in 2 main types - short pass filters and band pass filters.