Line scale comparison Nano3

This contribution will report on the results of the international line scale comparison Nano3, which was carried out between 2000 and 2003. The comparison was initiated by the BIPM working group on nanometrology as one of five comparisons in the field of nanometrology. Two high quality line scales of Zerodur and quartz with 280 mm graduations were chosen as transfer standards. They were measured by 13 national metrology institutes from 4 different metrology regions. The measurement uncertainties which were evaluated by the participants over the 280 mm length showed a variation from about 300 nm down to 30 nm.