Quote:
Originally Posted by robz
If Mylar is good enough for this purpose, why should it's surface accuracy be lousy for a mirror?
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Well
you just answered your question with the question itself:
Reflecting light from surface is not the same thing as passing the light through the same surface (doubled, if you like).
Mylar foil acts as a plan-parallel plate, so it is suitable for window, even if it is not perfectly flat and stretched. But to use it as mirror is something entirely different.
And, the very complicated method of adjusting the mylar film is just too complicated to be practical.. simple junk of polished glass does the better job, in a cheaper and more stable way, it is not temperature and air pressure dependent.
So why bother at all with all this?
GSO is Guan Sheng Optical company, a Taiwanese manufacturer of cheap (but good) and conventional glass mirrors.