Wide field-of-view imaging spectrometer using imaging fiber bundles

A field-of-view-folding approach is proposed to extend the field of view (FOV) of a dispersive imaging spectrometer after introducing several linear arrays of imaging fiber bundles to which to replace the slit. The fiber bundles can flexibly connect fore-optics with a spectrometer to yield an imaging fiber-optic spectrometer (IFOS). The technology of FOV segmenting and folding, which can decrease simultaneously the dimension and spectral distortion of the imaging spectrometer, is described in detail. Because of the sampling function of the fiber bundles, the IFOS is a double-sampling imaging system. We analyze the effect of fiber coupling on the modulation transfer function (MTF) and then develop a cascade MTF model to estimate the imaging performance of the IFOS. A spaceborne IFOS example is presented to describe how the method can be used.