The member 12 is made of a material having a low coefficient of {TAIL ~ thermal expansion} and high thermal conductivity, such as {HEAD ~ sapphire} or ruby 
The member 12 is made of a material having a low coefficient of { TAIL ~ thermal expansion } and high thermal conductivity , such as { HEAD ~ sapphire } or ruby
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 OTH HEAD HEAD HEAD HEAD HEAD OTH OTH