We developed the technology of microslice integral field units some years ago as the next step in SAURON type
microlens IFU design with typically 5 times more spatial elements (spaxels) for the same spectrograph and spectral
length aiming at 1,000,000 spaxels IFUs. A full instrument for laboratory demonstration composed of the fore-optics, the
IFU, the spectrograph and the detector has now been built and tested. It has about 10,000 spatial elements and spectra
150 pixel long. Our IFU has 5 cylindrical microlens arrays along the optical axis as opposed to one hexagonal array in
the previous design. Instead of imaging pupils on the spectrograph input focal plane, our IFU images short slitlets 17
pixel long that keep the spatial information along the spatial direction then giving 17 spaxels per slitlet instead of one in
pupil imaging. This removes most of the lost space between spectra leaving place for more and keeps the spatial
information over the element size while pupil images lose it. The fore-optics re-images the field on the input of the IFU.
They are made of cylindrical optics to get the desired different magnifications in both directions. All the optics and
detector fit in a cylinder 35 mm in diameter and 280 mm long. With a different set of fore-optics on a 4-m telescope, a
field of 43" x 6.7" with spatial elements of 0.14" x 0.22" could be observed so 12 of these mini-spectrographs would
cover a field surface area of about 1 arcmin2 and 120,000 spaxels.