A rare look at NASA’s next sharp-eyed space telescope
The central feature of the telescope is an exquisitely polished, concave primary mirror, 2.4 meters (7.9 feet) in diameter.
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Two Types of Telescopes
Instead of a concave lens near the eye ... This was the first working reflecting telescope. Other designers proved unable to grind mirrors with a regular curvature, so the reflector remained ...
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The Evolution Of The Telescope, From Galileo To Hubble And Beyond
He replaced the concave lens with a second convex ... Light travels into the telescope, bounces off a curved mirror at the bottom which aims it all into a focal point, where it hits a mirror ...