Left - The Figure shows the layout of three out of the four arms composing a channel of the Multi-Integral Field unit VESPER. Each channel is composed of 6 Integral Field Selectors (IFS, contiguous in the x direction) ~1.7"x1.5" each, and deployable along the y direction to probe an area of x*y~10"x58". The optical path starts from the focal plane where, upstream of the system, it is placed the image slicer. Right -The image slicer is made up of 192 mirrors of dimension 32x1mm. The 192 mirrors are divided into four groups (3 groups are shown), each of which feeds an arm. There are 192 pupil mirrors and four mirrors to fed the four arms. All the curved optical surfaces of VESPER are spherical. 

The size of one channel (four arms, 6 IFSs over 10"x58") is ~45 cm height, while a diameter of 3 m is needed for the rotation in this configuration. The size of the image slicer is about 50x20 cm.