transverse acoustic waves or perpendicular longitudinal waves can change the polarization. The acoustic waves induce a birefringent phase-shift, much like in a Pockels cell. The acousto-optic tunable filter, especially the dazzler, which can generate variable pulse shapes, is based on this principle. Modelocking Acousto-optic modulators are much faster than typical mechanical devices such as tiltable mirrors. The time it takes an AOM to shift the exiting beam in is roughly limited to the transit time of the sound wave across the beam (typically 5 to 100 ns). This is fast enough to create active modelocking in an ultrafast laser. When faster control is necessary electro-optic modulators are used. However, these require very high voltages (e.g. 1...10 kV), whereas AOMs offer more deflection range, simple design, and low power consumption (less than 3 W). Applications Q-switching Regenerative amplifiers Cavity dumping Modelocking Laser Doppler vibrometer RGB Laser Light Modulation for Digital Imaging of Photographic Film Confocal microscopy Synthetic array heterodyne detection Hyperspectral Imaging See also Acousto-optics Acousto-optic deflector Electro-optic modulator Jeffree cell Acousto-optical spectrometer Liquid crystal tunable filter Photoelasticity Pockels effect Frequency shifting External links Olympus Microscopy Resource Center References Optical devices