Abstract
Because of usability in less-restraint condition, the fNIRS measurement has been increasingly utilized for detecting human cerebral activity in many disciplines. There, however, they often suffer from motion artifacts caused by optode movement during subjects' task execution when the task includes motion. We propose a new method for removing the motion artifact caused by optode-setting instability. In such cases, the optode movement causes a signal contamination through the light reflection change at hair. In this method, the contaminants of specular reflection at hair are optically eliminated from the NIRS signal by utilizing linearly polarized light sources, detectors with orthogonally polarized analyzer, and a multidistance measurement using them. The method was validated with an optical phantom with haired surface. The optical absorbance change of a close source-detector (S-D) pair equipped with polarizers was very similar to that of distant S-D pairs even when these optodes were extraneously fluctuated. Using these signals, multidistance measurement can effectively eliminate contaminants from subject's motion as well as hemodynamics in scalp layer.
