A Bragg configuration gives a single first order output beam, which intensity is directly linked to the power of RF control signal, and which angle is directly linked to the RF frequency. By varying the frequency, the output laser beam angle is modified. A deflector is used to scan a laser beam over a range of angles, or to control with accuracy the output angle of the laser beam. The main parameters to qualify a deflector are 1. Deflexion angle range, 2. Resolution and 3. Random Access Time. The deflexion angle range is the maximum angle variation of the laser beam: it is linked to the frequency range of the device. The resolution of a deflector is the number of distinct directions which can be addressed by the deflector : it is linked to the deflexion angle range and laser divergence.

Two deflectors can be used in series and at right angles to give full two-dimensional scanning. Main Applications: Generation of pictures and graphics, Compensation of tracking errors in rotating polygon mirrors, Opticals tweezers - a laser beam is steered with an AO deflector in two dimensions to trap atoms or molecules, Two and Three dimensions measurements...

A frequency shifter uses the shift inherent in the acousto-optic interaction to up- or down-shift a laser's frequency. Two kinds of shifters can be distinguished : the fixed frequency shifter, and the variable frequency shifter. The frequency shift is directly equal to the RF frequency applied to the transducer(we must not forget that the output angle is also linked to the frequency : see deflectors). Various techniques can be used to shift the laser beam, such as multiple travels inside the shifter to double or triple the frequency shift, or a combination of two frequency shifters to achieve low amount of shift. Main application : optical heterodyning and interferometric applications, laser doppler velocimetry for particle velocity analysis in sprays.