Conducting resolved spectroscopy on large samples of very faint objects is a strong requirement for the Next Generation Space Telescope (NGST). We are presenting the IFMOS concept, a 1 to 5 microns integral field spectrograph developed under contract with ESA. Image slicers are feeding compact spectrograph modules with very few moving parts. The wide field survey mode has low spatial - low spectral resolution over a field similar to 46 x 40 arcsec(2) (0.19 arcsec per resolved element). The hi...