US Patent 11531249 Constant-frequency acousto-optic beam steering

A pair of acousto-optic deflectors (AODs) is used to steer a pair of laser beams to address individual atoms of an array of atoms so that the beams can conditionally induce a 2-photon transition between the atom's quantum energy levels. The first beam is deflected into a +1 diffraction order, resulting in an AOD output beam with a frequency greater than that of the respective AOD input beam. The second beam is deflected into a −1 diffraction order so that the AOD output beam has a frequency less than that of the respective AOD input beam. The equal and opposite frequency changes compensate it other so that the sum of the output frequencies remains constant.