{TAIL ~ The sensor} includes a light source and a receiver which is sensitive to {HEAD ~ its radiation} 
{ TAIL ~ The sensor } includes a light source and a receiver which is sensitive to { HEAD ~ its radiation }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD