US Patent 7304735 Broadband wavelength selective filter

An optical filter for the selective attenuation of specific wavelengths of light includes at least one spectrally dispersive element, such as a diffraction grating or prism, in combination with an optical filter. A dispersive element separates broadband light into a constituent wavelength spread in angle space. An optical filter, or filter array, can block and/or attenuate specific wavelengths or wavelength ranges of interest while the light is angularly dispersed. A second dispersive element can recombine this filtered, separated wavelength fan of light into a coaxial broadband beam having a smoother intensity profile than the unfiltered beam.