Patent ID: 11921254
Assignee: SOREQ NUCLEAR RESEARCH CENTER
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 13:
14. A seismic surveying method comprising the procedures of:
directing by a multibeam laser source a plurality of laser beams toward an instantaneous area of interest, said laser beams producing an assemblage of laser spots on said instantaneous area of interest;
acquiring a plurality of defocused images of speckle patterns produced by diffused reflections of said laser spots from an instantaneous area of interest, each speckle pattern corresponding to a respective laser spot and thus to a respective sensing point in said instantaneous area of interest;
determining relative displacements between corresponding speckle patterns in pairs of sequential images of received speckle patterns by:
estimating a course spatial displacement between said corresponding speckle patterns in each sequential pair of images;
aligning each pair of sequential images with each other according to said course spatial displacement estimation;
determining a fine relative spatial displacement between said corresponding speckle patterns in each pair of sequential images;
estimating a total relative spatial displacement between each pair of sequential images by combining said estimated coarse relative spatial displacement and said determined fine relative spatial displacement with a highest cross-correlation value; and

determining a respective time signal for each sensing point representing vibrations thereat from total relative displacements between speckle patterns respective of each sensing point.