Improvements of IMGC absolute gravimeter

International comparisons, periodically organized by the Bureau International des Poids et Mesures (BIPM) and in the future jointly with the Working Group on Gravimetry (WGG) of the Consultative Committee for Mass and Related Quantities (CCM) of the Comité International des Poids et Mesures (CIPM), show significant differences between absolute gravity measurements. Many sources of errors have been considered to evaluate each uncertainty budget, in spite of that, in some cases, the observed differences from an averaged value are statistically larger than expected by these evaluations; some causes of uncertainty cannot be well quantified because they are based on theoretical hypothesis. In this framework the Istituto di Metrologia “G. Colonnetti” (IMGC) is developing a second new gravimeter which will replace the old one, with the aim of decrease the uncertainty budget. It is derived from the original design, but it has been radically modified for what concerns the optical, mechanical and electronic system. The present paper underlines the improvements achieved with this second generation gravimeter.