A system for illuminating a sample with a spectrally filtered illumination source includes an illumination source configured to generate a beam of illumination having a first set of wavelengths. In addition, the system includes a wavelength filtering sub-system, a sample stage, an illumination sub-system, a detector, and an objective to focus illumination from the surface of one or more samples and focus the collected illumination to the detector. Further, the wavelength filtering sub-system includes one or more first dispersive elements positioned to introduce spatial dispersion into the beam, a spatial filter element, and one or more dispersive elements positioned to remove spatial dispersion from the beam. The spatial filter element is further positioned to pass at least a portion of the beam including a second set of wavelengths, wherein the second set of wavelengths is a subset of the first set of wavelengths.