An improved compact spectrometer system comprising an improved spatially variable filter is disclosed herein. A spatially variable filter may be configured to have a plurality of different transmission profiles at different locations of the filter, to spectrally separate light incident on the filter. The spatially variable filter may comprise a plurality of different filter regions having different transmission profiles, and a plurality of similar filter regions comprising similar transmission profiles. The spatially variable filter may be optically coupled to a detector comprising a plurality of detector elements configured to measure the intensity of light. The measurement data generated by the plurality of detector elements coupled to the plurality of similar filter regions can be used to determine a spatial variation on incident light intensity.