To measure the dynamic behavior of rotating fiber reinforced polymer structures, an optical diffraction grating based sensor has been developed to measure in-plane strain and out-of-plane tilts on the rotor surface with high spatio-temporal resolution. A novel modal analysis approach based on the combination of consecutive measurements with a known excitation and varying time delays was used to extract fully featured modal parameters from a rotating composite disk. The results of the diffraction grating based approach were compared to the results of a commercial triangulation sensor and a piezoresistive strain gauge and showed excellent SNR at surface speeds up to 280 m/s.