Acousto-optic deflector
An acousto-optic deflector is a device that uses the interaction between sound waves and light waves to deflect or redirect a laser beam. AODs are essentially the same as acousto-optic modulators. In both an AOM and an AOD, the amplitude and frequency of different orders are adjusted as light is diffracted.
Operation
In the operation of an acousto-optic deflector the power driving the acoustic transducer is kept on, at a constant level, while the acoustic frequency is varied to deflect the beam to different angular positions. The acousto-optic deflector makes use of the acoustic frequency dependent diffraction angle, where a change in the angle as a function of the change in frequency given as,where is the optical wavelength and is the velocity of the acoustic wave.