In article , whunter <whunterjr@xxxxxxxx> writes
What I implied, but did not stress: Glass, a 'non-crystalline' melt of
boron, silicon oxides and other elements, lacks the radiation sensitive
organic carbon bonds. Glass is so resistant to radiation damage that
zillions of $ have been invested in the development of processes for
encapsulation of extrEMEly radioactive waste for 'eternity'. Depending
on the ingredients of a specific glass, glass can be susceptible to
'fogging' or color change induced by intense ionizing radiation.
Distilling all this to the pragmatics of a discolored Zuiko from rare
earth containing coatings: First, the ionizing radiation level is
extremely low. While difficult to separate radiation induced change
from chemical degradation of the organic coatings, the science says the
damage is on the exterior of the lens, not within the inorganic glass
matrix.
All of that would be fine Bill, but if you take one of these lenses
apart and isolate the yellow element, it doesn't take much work to
demonstrate that the discoloration is in the *volume* of the glass, and
certainly not just on the surface. At least, on the ones I have
examined, that is the case - I don't preclude that there are examples
where only the coating has yellowed. Many single coatins had a yellow
sheen in the first place, but that isn't what we are talking about here.
Also, I am not aware of ANY organic compounds used for coatings - the
coating fabrication, being a plasma deposoition process, tends to
preclude most organics. I have specified diamond coating on some
optics, which technically is an organic material but not an organic
compound, and most coating materials are generally MgF or similar
materials.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's pissed.
Python Philosophers
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