Synchronous imaging is used for the dynamic space-domain studies of vibration profiles in capacitively driven, thin n + doped polysilicon microbridges oscillating at rf frequencies. Fast and high-resolution actuation profile measurements of micromachined resonators are useful when significant device nonlinearities are present. For example, bridges under compressive stress near the critical Euler value often reveal complex dynamics stemming from a state close to the onset of buckling. This leads to enhanced sensitivity of the vibration modes to external conditions, such as pressure, temperatures, and chemical composition, the global behavior of which can be conveniently evaluated using synchronous imaging combined with spectral measurements. We performed an experimental study of high drive amplitude and ambient pressure effect on the resonant vibration profiles in electrically driven microbridges near critical buckling. Numerical analysis of electrostatically driven post-buckled microbridges supports the richness of complex vibration dynamics that are possible in such microelectromechanical devices. ©2012 American Institue of Physics.