Patent ID: 8417307

Claim:
A blood oximeter for measuring the oxygenation and at least one other parameter of flowing blood in living tissue, comprising: an infrared light source configured to emit light of infrared wavelengths into the tissue; a red laser with a laser cavity configured to emit a red laser beam into the tissue, the red laser being adapted to allow a part of the red laser beam which is scattered by the tissue to re-enter into the laser cavity; a red laser beam sensor for measuring the light emitted from the red laser, the red laser beam sensor outputting a signal which varies in accordance with the self-mixing interferometric effect between the red laser beam and the scattered red laser beam; a pulse oximetry photodiode configured to receive the infrared wavelength light from the infrared light source which has passed through the tissues and to receive the red laser beam which has passed through the tissue from the red laser; and one or more processing units which receives and processes output signals from the red laser beam sensor and the pulse oximetry photodiode to determine an arterial blood oxygen concentration and the at least one other parameter.