Proceedings PaperOptical cardiograph using laser speckle
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The deformation of a vein due to heart beats is measured by sticking a small mirror to the skin and recording the deviation of a laser beam incident upon the mirror as a function of time. As an example of possible clinical applications of this method the curves (vein deformation vs. time) corresponding to an individual executing a physical effort of increasing intensity are presented. In another experiment the skin is directly illuminated without interposition of a mirror. The reflected speckle pattern is deformed when the pulse is passing through. It is shown that the contrast of the recorded speckle pattern is a minimum at the instants of time when the vein deformation speed is a maximum. This allows remote measuring of heart beats frequency by a fully non-invasive technique.