Cerebral oximetry (also known as Near Infrared Spectroscopy or NIRS) provides a non-invasive measure of regional cerebral tissue oxygen saturation which reflects local oxygen supply and demand, and could indicate cerebral ischemia when desaturation occurs. The FORE-SIGHT cerebral oximeter is a non-invasive, optically-based near-infrared spectrometer that continuously estimates absolute cerebral tissue oxygen saturation, and works based on the principal that hemoglobin's two forms -- oxygenated and deoxygenated -- absorb light differently. The sensor projects laser into the brain at four different wavelengths (to maximize accuracy), with the reflected light being analyzed via algorithm to an absolute value of cerebral saturation. The FORE-SIGHT has been validated in several studies that have shown good precision of the cerebral tissue oxygen saturation value.