Angular Alignment of Separated Raman Beams Based on Optical Interference in Atom-Interferometer Gyroscopes

The angular alignment of the effective wave vectors of spatially separated Raman beams is crucial for the closed interferometric paths in atom-interferometer gyroscopes. A sensitive and reliable method based on the optical interference is proposed for the preliminary alignment of Raman beams in a four-pulse atom interferometer. The distribution of the optical interference fringe is perpendicular to the angular deviation, while the fringe width reveals the size of the misaligned angle. The alignment method can also be extended in the atom-interferometer gyroscopes with three pairs of separated Raman beams.