Method and a system for reducing motion artefacts in speckle pattern signal

A system for reducing motion artefacts in a speckle pattern signal, the system comprising:

• a light source configured to illuminate a region of a living being by a light signal for forming a speckle pattern;
• an imaging unit configured to acquire a sequence of images representing the speckle pattern at the region of the living being;
• a processor configured to:
• receive the sequence of images from the imaging unit;
• extract a speckle pattern signal from the received sequence of images to form a wave propagation signal representing a variation in time of a pressure wave or a volumetric flow wave in the living being;
• receive a motion compensation signal based on an optical measurement representing the region of the living being, wherein the motion compensation signal represents a variation in time of motion of the living being;
• and
• perform motion compensation of the wave propagation signal based on the motion compensation signal.