Coded aperture spectral imaging device

An imaging spectrometer, comprising:

• an entrance opening configured to admit light to the spectrometer, a coded aperture, at least one dispersive element, a two-dimensional array detector, and a plurality of converging optical elements;
• wherein:
• the plurality of converging optical elements are configured to focus light from the entrance opening at the coded aperture, and to focus light from the coded aperture at the detector,
• the coded aperture is arranged to modulate light from the entrance opening in at least one of the spatial and spectral domain,
• the at least one dispersive element comprises a dispersive element between the coded aperture and the detector,
• wherein the at least one converging optical element comprises at least one concave reflector;
• wherein the coded aperture is operable in a transmissive mode, such that a coded pattern of light is transmitted towards the detector by the coded aperture, and the inverse of the coded pattern of light is dumped and/or absorbed by the coded aperture.