Notch filters allow blocking a specific wavelength of light (up to >OD6), while showing high transmittance for the remaining part of the spectrum. The bandwidth of the blockband can be as narrow as 10 nm in the VIS range. Multi-notch filters block up to 4 different wavelengths. Notch filters are composed of a complex multilayer stack deposited onto glass substrates. They can be designed for user defined blocking wavelength, blocking depth and angle of incidence.