  FALCON is an original concept for a next generation spectrograph at ESO VLT
or at future ELTs. It is a spectrograph including multiple small integral field
units (IFUs) which can be deployed within a large field of view such as that of
VLT/GIRAFFE. In FALCON, each IFU features an adaptive optics correction using
off-axis natural reference stars in order to combine, in the 0.8-1.8 \mu m
wavelength range, spatial and spectral resolutions (0.1-0.15 arcsec and
R=10000+/-5000). These conditions are ideally suited for distant galaxy
studies, which should be done within fields of view larger than the galaxy
clustering scales (4-9 Mpc), i.e. foV > 100 arcmin2. Instead of compensating
the whole field, the adaptive correction will be performed locally on each IFU.
This implies to use small miniaturized devices both for adaptive optics
correction and wavefront sensing. Applications to high latitude fields imply to
use atmospheric tomography because the stars required for wavefront sensing
will be in most of the cases far outside the isoplanatic patch.
