Acousto-optical elements have successfully replaced planar filters in many positions. The white confocal, regarded as the fully spectrally tunable confocal microscope, was not possible without this technique. Acousto-optical elements are highly transparent, quickly tunable and allow many colors to be managed simultaneously. As they show a strong dependence in polarization and have comparably small dimensions, their active part is used to modify and guide the laser illumination light, thereby leaving the principal beam (0th order) unaffected. Excitation color selection and attenuation (excitation filtering), as well as separation of illumination and detection light (beam splitting) are the main fields of application.