Acousto-optic Device

Acousto-optics is a branch of physics that studies the interactions between sound waves and light waves,
especially the diffraction of laser lightby ultrasound (or sound in general) through an ultrasonic grating.

Three categories of acousto-optic devices will be discussed. They include the acousto-optic modulator, 
filter and deflector.

1.Acousto-optic modulator
  By varying the parameters of the acoustic wave, including the amplitude, phase, 
  frequency and polarization, properties of the optical wave may be modulated. 
  The acousto-optic interaction also makes it possible to modulate the optical beam 
  by both temporal and spatial modulation.

2.Acousto-optic filter
  The principle behind the operation of acousto-optic filters is based on the wavelength of 
  the diffracted light being dependent on the acoustic frequency. 
  By tuning the frequency of the acoustic wave, the desired wavelength of the optical wave can 
  be diffracted acousto-optically.

3.Acousto-optic deflectors
  An acousto-optic deflector spatially controls the optical beam. 
  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.