Systems and methods are disclosed for measuring a physiological signal of a patient without having to contact the patient. A system can include a laser configured to provide an optical beam to a surface associated with a patient. A detector receives light from the surface in response to the optical beam. A controller is configured to generate velocity data representing a velocity of the surface based on the detected interference of the optical beam and the reflected light. A processor computes a corresponding displacement waveform representing displacement of the surface based on the velocity waveform, the displacement waveform representing the physiological condition.
