A conventional spatial heterodyne spectrometer (SHS) comprises a beam splitter and a pair of diffraction gratings, one in each arm of the SHS. The beam splitter separates an input beam of light into first and second sub-beams for transmission to a respective diffraction grating, and then recombines the diffracted sub-beams for focusing onto a camera. A field widened SHS enables much larger range of input angles of the original beam to be focused onto the camera, so that a broader range of wavelengths may be collected. Increasing the range of wavelengths may be provided by one or more of the following: combining the beam splitter with a field widening prism, making one diffraction grating farther from the beam splitter than the other, and placing a plurality of diffraction gratings in each arm of the SHS.