Fringe signal effect on the absolute gravimeter FG5 No. 215

Abstract

For highly accurate absolute gravity measurements (on the level of 1-2 $\mu Gal$) using FG5 gravimeters it is necessary to ensure a correct adjustment of the meter and to guarantee many optimal conditions at the observing site. Effects of the interference fringe size on the FG5 No. 215 results were experimentally studied by absolute gravity measurements repeated under different conditions. The fringe signal size was changed for first by rotation of the Faraday isolator and for second with the help of additional polarization filter. The relation between the gravity and fringe signal size within the range of 180-430 mV was approximated by a regression line with the regression coefficient of 0.015 ± 0.002 $\mu Gal$/mV and 0.011 ± 0.002 $\mu Gal$/mV, respectively. Although the fringe signal effect is not dramatic for FG5 No. 215, the correction of FG5 results to the same fringe signal level improve the accuracy of absolute measurements.