5.1.1 Integral Field Concept

The integral field unit (IFU) allows FIFI-LS to obtain spectra at each point in its FOV in contrast to a spectrometer with a slit which only provides spectra along the slit. Each channel in FIFI-LS has an IFU, which consists of 15 specialized mirrors to "slice" the two dimensional 5x5 pixel FOV into five slices (of five pixels length each) which are then reorganized along a (one dimensional) line (25x1 pixel). This line forms the entrance slit of the actual spectrometer. The diffraction grating disperses the incoming light in the spectral dimension. Finally the dispersed light reaches the 16x25 pixel detector array. The result is a "data cube" with 5x5 spatial pixels (spaxels) and 16 pixels in the spectral "dimension". Figure 5-1 shows the concept.

Illustration of the field imaging concept in FIFI-LS

Figure 5-1: Illustration of the field imaging concept in FIFI-LS. The optics slice the rows of the 5x5 pixel field of view into a 25x1 pixel pseudo slit.

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