Cardiac monitoring using laser speckle

Laser speckle is an interference phenomena which is always present when a laser is used. Time-average speckle interferograms of the left and right side of the chest of a normal healthy subject were recorded at the Fourier transform plane on a fine grain photographic plate, while the subject held his breath. The interferogram was analysed by the point wise method and a graph was drawn between the position and the displacements at corresponding points on the chest wall* The associated displacements of the chest wall due to heart action are correlated with cardiac function.