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Re: Knife Edge Testing

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Posted by Robert May on May 6, 1999 18:30:52 UTC

Make your Couder Masks, do the calculations for what the measurements should be for a parabola and do the measuring in a dark room so you can see the shadows well. You may be making a hyperbola and don't know it until you do the measuring. Don't worry about the exact FL of the mirror (let the hole fill the mirror if that is what it wants to do) but rather get the shape correct. Remember that the longer and wider the stroke is, the more it will cause the center to deepen. If you post again, I'd like to see the numbers and what you have recently measured - include the size and Radius of Curvature of the mirror.

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