how to make a paraboloid mirror with focal length of 10 feet
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Satellite dishes are typically about 3 feet or less focal length. How can I make an optical mirror that is about 3 times that, and about 4 feet in diameter? |
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A side-view of such a parabola would have a curve of y = (1/40) x^2 For a diameter of 4 feet, the outer edge would be only 1.2” raised from the very center, which would make for very difficult manufacturing. You’d need to follow that y = (1/40) x^2 curve very carefully in order to have a functioning parabolic mirror. Most builds use sections of flat stock that are bent to conform to the connective geometry, such as http://www.instructables.com/id/How-to-build-a-strikeheliostatstrike-paraboli/, but that method wouldn’t be accurate enough for your gentle curve. I used the formula for focus, simplified since a and c can be zero, but this excel sheet is a bit more robust than a simple calculation: http://www.greenpowerscience.com/PARABOLAFORMULA.php |
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