Single-Shot Microvibration Detection and Its Application in Spatial Multipoints Vibration Sensing

Extraction of micro-vibration information from a single-shot speckle image is realized base on the row-by-row exposure mechanism of a rolling shutter camera and the high intensity of laser speckle. Normalized cross correlation and cubic spline interpolation algorithm is firstly used between nonoverlapping gray scales of adjacent rows to infer micro-displacement information. With number of rows set as 342, wide frequency range from 300 Hz to 20 kHz sinusoid signals are recovered with relative errors smaller than 2%. For low frequency signals from 40 Hz to 300 Hz, the relative errors of the extracted frequency are smaller than 5%. The effects of number of sampling cycles (NSC) and sampling points in unit period on the system performance are investigated and high accuracy is obtained with NSC of 4 and sampling points of 3 per signal period. In a single shot image, spatial multi points vibration detection scheme is presented and experimentally realized. The representative signals of 5 kHz, 10 kHz and 20 kHz are successfully extracted in the multidimensional scenes of 1D, 2D and 3D respectively, and the relative errors are all within 0.5%. This scheme can be potentially used in air surveillance for wide range remote sensing of interested object or sounding.