Thread: How can I tell if/whether my 4.5" mirror is spherical/parabolic
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Old 04-09-2008, 11:13 PM
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Merlin66 (Ken)
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Join Date: Oct 2005
Location: Junortoun Vic
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Fastest and easiest way to check is using a Ronchi grating focussed on a star with 3- 4 lines visible. If the lines are straight is parabolic; if they curve then its spherical.
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