Table 1: Effect of sputtering on “CCR” at λ=118.8 µm.

Mirror Samples	R Before Ion Bombardment		R after Ion Bombardment
	Single Mirror	“Retro-Reflector”	Single Mirror	“Retro-Reflector”
O-free copper	97.7%	93.5%	97.8%	93.7%
CuCr	99.2%	97.6%	97%	91%