Fig. 1. Schematic diagram of the optical interference optical path inside the cold atom gravimeter. (a) Overall schematic and the setup for the whole gravimeter inclination measurement. (b) Specific schematic: the setup for retro-reflection Raman beam inclination measurements.

Fig. 2. Schematic diagram of the calculation process.

Fig. 3. Simulation of the relationship among the measured angle variation, the actual angle variation, and α₁. The ratio is the measured angle deviation divided by the true angle variation.

Fig. 4. A raw interferogram versus the image after filtering using our method. Top: original interferogram. Bottom: filtering with our method.

Fig. 5. Results of angular variation measurement in the field.

Fig. 6. Apparatus of the nonlinearity test.

Fig. 7. Nonlinearity test results. O.O.I. is the output of our optical interference method; O.E.T. is the output of the ET; O.M.T. is the output of the MT; and O.B.A. is the output of the beam analyzer. The blue circles represent the measured data. The red solid lines are the linearly fitted results of the output of the tiltmeters and the beam analyzer. The orange curves represent the residual. The first set of results [(a), (d), and (g)] has been averaged over 20 s. The second and third sets of results [(b), (e), and (h); (c), (f), and (i)] have been averaged over 50 s to reduce the effect of small vibrations on the results.

Fig. 8. Long-term test results. Storage issues resulted in the loss of some data.

Fig. 9. Variation of measured gravity with inclination measurement. The blue triangles and dashed curves represent the five data points and the corresponding fitting results, respectively. The red circles are the appended points and the red solid curves are the fitting results of the seven points.