According to the teachings of the present invention, {HEAD ~ a system} is provided which retains the versatility and {TAIL ~ benefits} of reflective optics while eliminating the disadvantages of refractive optical systems 
retains
According to the teachings of the present invention , { HEAD ~ a system } is provided which retains the versatility and { TAIL ~ benefits } of reflective optics while eliminating the disadvantages of refractive optical systems
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH