In this talk I will outline the future perspective of optical spectroscopic study in the era of very large (VLT/Keck)
and extremely large telescope (TMT/E-ELT). In particular, I will focus on ESPRESSO, the radial velocity machine at
ESO-VLT (deliver: mid 2017) that will lead for the first time a 16-mt equivalent optical telescope equipped with an
high resolution ultra stable spectrograph. Pushing the limit toward 40mt class telescope I will present the case of
ESO-HIRES , an high resolution fiber feed spectrograph for the Extremely Large Telescope currently evaluated by ESO
for Phase1 design study.
The talk will also outline how the newly available instruments coupled with large telescope aperture (30-40my) could be exploited for the optical spectroscopic confirmation of FERMI Unidentified Gamma-ray Sources and how they will improve the determination of the redshift of BL Lacertae.