The device includes a first subset of {TAIL ~ light modulators} and a second subset of {HEAD ~ light modulators} 
The device includes a first subset of { TAIL ~ light modulators } and a second subset of { HEAD ~ light modulators }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD