De-coupling the Coriolis effect from Raman beams alignment in a fountain atom gravimeter

The alignment of Raman beams is important for high-precision atom interferometry gravimeters, and tilt modulation experiments are usually carried out to calibrate the direction of Raman beams. However, the Coriolis effect could be changed during the tilt modulation experiment, thus introducing a deviation in the alignment of Raman beams. In this work, a method of rotating the sensor head by 90° to eliminate the impact of the Coriolis effect on Raman beams' alignment in a fountain atom gravimeter was proposed and demonstrated experimentally. Using this method, the alignment uncertainty of the Raman beams in the atom gravimeter was reduced to 11 μrad, which contributed an uncertainty of less than 0.1 μGal (1 μGal = 1 × 10-8 m/s2) to the gravity measurement. Further simulations explained the experimental results and pointed out a way to reduce the Coriolis effect in atom gravimeters.