In some embodiments, {TAIL ~ another light source} 314 and associated optics may be provided by {HEAD ~ an analyzer} 
In some embodiments , { TAIL ~ another light source } 314 and associated optics may be provided by { HEAD ~ an analyzer }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD