Rotating furnace
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A rotating furnace is a device for making solid objects which have concave surfaces that are segments of axially symmetrical paraboloids. Usually, the objects are made of glass. The furnace makes use
Parabolic shape formed by a liquid surface under rotation. Two liquids of different densities completely fill a narrow space between two sheets of plexiglass. The gap between the sheets is closed at the bottom, sides and top. The whole assembly is rotating around a vertical axis passing through the center.
Primary mirror
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A primary mirror is the principal light-gathering surface of a reflecting telescope.
Rotating furnace
…identical to the shape of a reflecting telescope's primary focusing mirror. Paraboloids can be used in various ways, including (after being silvered) as primary mirrors in reflecting telescopes and solar cookers. The furnace includes a mechanism that rotates an open-topped container at constant speed around a vertical…
Six of the 18 primary mirrors of the James Webb Space Telescope being prepared for acceptance testing.
The correctly ground backup primary mirror built by Eastman Kodak for the Hubble space telescope (the mirror was never coated with a reflective surface, hence its honeycomb support structure is visible). It now resides in the National Air and Space Museum in Washington, DC.
The largest non-segmented mirror in an optical telescope in 2009, one of the Large Binocular Telescope's two mirrors.