b) illuminating the sample within {HEAD ~ said test element} with light of {TAIL ~ NIR wavelengths}, 
b ) illuminating the sample within { HEAD ~ said test element } with light of { TAIL ~ NIR wavelengths } ,
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH