The optical surfaces have {HEAD ~ a high value} of {TAIL ~ elastic modulus}, reducing coma and other aberrations associated gravity and acceleration 
The optical surfaces have { HEAD ~ a high value } of { TAIL ~ elastic modulus } , reducing coma and other aberrations associated gravity and acceleration
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH