A non-contact method and apparatus for continuously monitoring a
physiological event in a human or animal, such as blood pressure, which
involves utilizing a laser-based interferometer system to produce a
waveform that is representative of continuous blood pressure in a
subject. The invention may preferably utilize a laser Doppler vibrometer
which is oriented to produce a laser beam directed toward the subject
substantially perpendicular to a skin surface of the subject wherein the
skin surface is moveable in response to blood pressure. The vibrometer is
sensitive to motion of the skin surface in a direction parallel to the
laser beam and produces a signal representative of this motion. By
plotting the velocity of the skin surface movement in the direction
parallel to the laser beam with respect to time, a waveform is produced
that has been found to be representative of the blood pressure waveform
and highly defined to thereby permit accurate timing analysis thereof
relating to cardiac cycles.