Optical seismic surveying system

An optical seismic surveying system comprising:

• a multibeam laser source including a plurality of laser sources and a Diffractive Optical Element, said plurality of laser sources configured to direct respective laser beams toward a single common focal point, said Diffractive Optical Element being located at said single common focal point, said Diffractive Optical Element configured to split each of said laser beams into a plurality of laser beams and to direct said laser beams toward an instantaneous area of interest, said laser beams impinging on said instantaneous area of interest and producing a laser spot assemblage, said laser spot assemblage including a plurality of laser spots;
• an imager, directed toward said instantaneous area of interest, said imager including an optical arrangement and an imaging sensor, said imager configured to acquire a plurality of defocused images of speckle patterns produced by diffused reflections of said laser spots from said instantaneous area of interest toward said imager, each speckle pattern corresponding to a respective laser spot and thus to a respective sensing point in said instantaneous area of interest;
• and
• a processor, coupled with said imager, said processor configured to determine a relative displacement between corresponding speckle patterns in sequential pairs of images, said processor further configured to determine a respective time signal for each sensing point representing vibrations thereat from said relative displacement between speckles patterns respective of each sensing point.