AOM is the abbreviation of "Acousto-optic Modulator". In the show laser industry this term defines a component which makes a static, non-modulating laser beam an analog modulated laser system. This way of creating an analog modulation was used for gas laser systems, whereas it mostly isn't any more for contemporary show laser systems, because the single laser sources themselves normally can modulate very much more efficiently.
An AOM is a glass or crystal with a Piezo-transductor (of sound waves) on one side and an (sound waves) absorber on its other side. Incident light is deflected from its actual direction by the (moving phase) diffraction grating, generated by the sound waves, traversing the glass/crystal. The itensity depends on the frequency.
An AOM is also called 'Bragg cell'.

See PCAOM as well.