  We present the optical and cryo-mechanical solutions for the Spectrograph of
VSI (VLTI Spectro-Imager), the second generation near-infrared (J, H and K
bands) interferometric instrument for the VLTI. The peculiarity of this
spectrograph is represented by the Integrated Optics (IO) beam-combiner, a
small and delicate component which is located inside the cryostat and makes VSI
capable to coherently combine 4, 6 or even 8 telescopes. The optics have been
specifically designed to match the IO combiner output with the IR detector
still preserving the needed spatial and spectral sampling, as well as the
required fringe spacing. A compact device that allows us to interchange
spectral resolutions (from R=200 to R=12000), is also presented.
