We sometimes see fingerprints on the concave sides of AR lenses where the operators have flipped them over (They always coat the concave side first).
I am seeing such fingerprints at the moment. They are invisible, even under an arc lamp, unless I breathe on the lens.
I am assuming that breathing on them would make no difference if the fingerprints were under the coating, but I do not understand why I cannot clean them off with cloths, detergents and solvents etc.
Perhaps touching the lens immediately after a side has been coated causes damage and leaves a permanent mark? It has been suggested that lenses at the bottom of a calotte may become slightly overcoated with material when the other side is coated. Is this possible?
On the good side, as far as I am aware, there have been no complaints by customers, but I find the whole situation alarming, and would like the operators not to touch the faces of the lenses at all. This would not be easy to implement or police however.
Any suggestions, or am I worrying needlessly?
Falstaff.
Bookmarks