Patent ID: 7831298

Claim:
A method for optically measuring blood in lung, comprising: directing to a target area of a lung light in two spectral bands centered at two different wavelengths at which oxygenated blood and the de-oxygenated blood in the target area possess distinctively different absorption characteristics, wherein the two different wavelengths are selected to be located respectively at a lower side and upper side of a light wavelength at which absorption of light by the oxygenated blood equals absorption of light by the de-oxygenated blood; measuring reflection of the light from the target area of the lung in the two spectral bands centered at the two different wavelengths to obtain optical images of the target area of the lung at different depths from a surface of the target area; and processing the obtained optical images to extract information on an oxygen exchange state in blood present at the target area of the lung to produce a map of the oxygen exchange state in blood at different depths at each location where the light enters the target area.