The need for a wide-field IFU at 1 micron

A wide-field IFU (1'x1') sensitive to near-IR light at 950 to 1300nm is a key missing parameter space for the VLT ESO facilities. Such an IFU could characterize the universe during reionization at redshifts 7-10, using Ly-alpha emitters, and measure the sizes of ionization bubbles. Such an IFU could detect key spectral lines, such as Hα and [O III], which are redshifted into the near-IR at intermediate redshifts. Such a wide-field near-IR IFU would complement the near-IR capabilities of the ELT. We will present key science cases for such an IFU and discuss possible concepts.