Evaluating the effect of wavefront aberrations in an atom gravimeter^*

Abstract The effect of wavefront aberrations, arising from both Raman beam phase distribution and atomic cloud thermal expansion, represents a critical error in atom gravimeters. This work introduces a strategy to reduce and evaluate the effect of wavefront aberrations in an atom gravimeter. First, the optical elements were installed inside the vacuum chamber to minimize the uncertainty of wavefront aberrations effect; Second, a method based on combining precise optical surface measurements with atomic cloud parameters characterization was employed to evaluate this effect; finally, two distinct modulation experiments were conducted to verify the correctness of the evaluation results. Based on this strategy, the uncertainty of wavefront aberrations effect was determined to be 1.4 µGal (1 µGal = 1 × 10 −8 m s −2 ), and the total uncertainty of the atom gravimeter was thus reduced to 1.6 µGal. This study proposes a comprehensive methodology for evaluating the effect of wavefront aberrations in atom gravimeters, which will significantly advance the development of atom interferometers toward higher precision measurements.