Figure 2. Schematic illustration of the path of light photons through tissue, which are emitted by the O2C device from two sources (laser light and white light source). The white light is scattered and returned to the detectors of the O2C probe. Depending on the degree of blood cell oxygenation, specific spectra of backscattered light can be measured and the local amount of blood can be calculated from this method. By applying the Doppler principle, the backscattered laser light gives additional information about the movement of the erythrocytes, which determines blood flow. With kind permisson of LEA Medizintechnik, Germany.