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Rugo
I can see from this response that you are only looking for a response that fits your pre-concieved view.
Any kind of `number' certification ( including interferometry ) can selectively ignore conditions that mean a 'silk purse' is actually a 'sows ear' Bad turned edges , surface roughness, astigmatism, irregular distortion etc, I've seen them all on mirrors that looked like gems on paper.
You'll find just as much respect out there for the work of people who rely on every mirror being testimony to their abilities and standards, as those that rely on numbers to decide when a mirror should go out the door.
I learnt long ago from star testing on the bench that a 'high strehl' mirror on paper can produce a lousy star test , but that is another story.
To reiterate on my last post a piece of paper is just a piece of paper, and your mirror will be what it is regardless so trust your eyes only.
Mark
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