A technique and apparatus for noncontact dynamic parameter measurement of micro- and macrodevices using an acousto-optic (AO) deflector for scanning is introduced. This system adopts an AO deflector to induce scanning in the laser beam rather than deflecting mirror or the movement of the X- Y stages to improve the positioning accuracy. The apparatus for incorporating a homodyne system in a laser scanning system is described. The system is composed of an interference technique by which the frequency shift induced in the scanning beam using the AO deflector is canceled out. Experimental results on measuring the dynamic parameter of the hard disk surface and the slider head on different scanning points are discussed.