A digital speckle pattern interferometer based on a complementary metal-oxide semiconductor (CMOS) camera is described. The temporal evolution of dynamic deformation is measured using interframe phase stepping. The flexibility of the CMOS detector is used to identify regions of interest with full-field time-averaged measurements and then to interrogate those regions with time-resolved measurements sampled at up to 70 kHz. A numerical and analytical investigation shows that the maximum surface velocity that can be reliably measured with interframe phase stepping corresponds to +/-0.3 times the surface velocity at which the interferogram is sampled at the Nyquist limit.
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