A tunable spectral filter, comprising: a first tunable dispersive element, wherein a dispersion of the first tunable dispersive element is adjustable, wherein the first tunable dispersive element is configured to introduce spectral dispersion to an illumination beam; a first optical element, the first optical element configured to receive the illumination beam from the first tunable dispersive element and focus the illumination beam at a focal plane, wherein a spatial distribution of a spectrum of the illumination beam at the focal plane is controllable by adjusting the dispersion of the first tunable dispersive element; a spatial filtering element located at the focal plane, wherein the spatial filtering element filters a spectrum of the illumination beam based on the spatial distribution of the spectrum of the illumination beam at the focal plane; a second optical element configured to collect the illumination beam having a filtered spectrum from the spatial filtering element; a second tunable dispersive element configured to receive the illumination beam from the second optical element, wherein a dispersion of the second tunable dispersive element is configured to correspond to the dispersion of the first tunable dispersive element, wherein the second tunable dispersive element is configured to remove the spectral dispersion introduced by the first tunable dispersive element from the illumination beam a controller communicatively coupled to the first tunable dispersive element, the second tunable dispersive element and the spatial filtering element, wherein the controller is configured to modify the dispersion characteristics of the first tunable dispersive element and second tunable dispersive element to modify the distribution of the spectrum of the illumination beam on the spatial filtering element and to adjust the spectral transmittance distribution of the spatial filtering element; and wherein both of the first tunable dispersive element and the second tunable dispersive element each comprise a diffraction grating, wherein the diffraction gratings each comprise an acousto-optic deflector; wherein the second tunable dispersive element is oriented with respect to the illumination beam from the second optical element such that the distributed spectral components of the illumination beam recombine and follow a common propagation path such that the illumination beam exiting the second tunable dispersive element is a spectrally-filtered version of the input illumination beam. a first tunable dispersive element, wherein a dispersion of the first tunable dispersive element is adjustable, wherein the first tunable dispersive element is configured to introduce spectral dispersion to an illumination beam; a first optical element, the first optical element configured to receive the illumination beam from the first tunable dispersive element and focus the illumination beam at a focal plane, wherein a spatial distribution of a spectrum of the illumination beam at the focal plane is controllable by adjusting the dispersion of the first tunable dispersive element; a spatial filtering element located at the focal plane, wherein the spatial filtering element filters a spectrum of the illumination beam based on the spatial distribution of the spectrum of the illumination beam at the focal plane; a second optical element configured to collect the illumination beam having a filtered spectrum from the spatial filtering element; a second tunable dispersive element configured to receive the illumination beam from the second optical element, wherein a dispersion of the second tunable dispersive element is configured to correspond to the dispersion of the first tunable dispersive element, wherein the second tunable dispersive element is configured to remove the spectral dispersion introduced by the first tunable dispersive element from the illumination beam a controller communicatively coupled to the first tunable dispersive element, the second tunable dispersive element and the spatial filtering element, wherein the controller is configured to modify the dispersion characteristics of the first tunable dispersive element and second tunable dispersive element to modify the distribution of the spectrum of the illumination beam on the spatial filtering element and to adjust the spectral transmittance distribution of the spatial filtering element; and wherein both of the first tunable dispersive element and the second tunable dispersive element each comprise a diffraction grating, wherein the diffraction gratings each comprise an acousto-optic deflector; wherein the second tunable dispersive element is oriented with respect to the illumination beam from the second optical element such that the distributed spectral components of the illumination beam recombine and follow a common propagation path such that the illumination beam exiting the second tunable dispersive element is a spectrally-filtered version of the input illumination beam.