{HEAD ~ The time delay unit} also includes a reflecting element for reflecting the optical signal back to the dispersive element along an optical path {TAIL ~ whose length} is a function of the angle 
{ HEAD ~ The time delay unit } also includes a reflecting element for reflecting the optical signal back to the dispersive element along an optical path { TAIL ~ whose length } is a function of the angle
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH