Optical designs of fore-optics and Advanced Image Slicer (AIS) systems made for the second generation VLT instruments KMOS1 and MUSE2,3 conceptual design studies are presented. KMOS is an infrared multi-integral-field spectrograph with 24 fields, each 2.8" x 2.8" with a 0.2" resolution, patrolling a 7' field. The described optics of KMOS are the fore-optics, from the images given by the pickoff system to the slicers, and the slicer systems themselves. The study also includes a derotator design in case the instrument would have been too heavy to be attached to the telescope. MUSE is an integral field spectrograph for the 0.465 µm to 1 µm bandwidth with a 1' x 1' field and a resolution of 0.2". Two optical designs were proposed, one mostly transmissive which is now the baseline, the other mostly using reflective optics. The later is described in this paper. It includes a derotator, an atmospheric dispersion corrector, a transmissive removable magnifier, a transmissive field splitter that cut the field in 24 subfields, the relay optics of each subfield to each slicer and the slicer systems. While MUSE is for the visible and would then in principle need transmissive optics, the use of reflective optics is justified because its minimum wavelength is 0.465 µm; modern reflective coatings give transmission larger than 98% for these wavelengths. We discuss the development of the manufacturing of AIS to extend its application to the visible from its actual use in the IR.