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Newton's Telescope Design


At the left is a curved mirror AB, which brings light coming in from the right from some distant object to a focus(the mirror’s focal length is the distance to the focus). Along the way the light is intercepted by a small flat mirror CD and sent off to the side so the focus, where the image of the distant object is formed, is at E. A small lens at F is used as an eyepiece to magnify the image for the observer’s eye. The basic arrangement resembles the Keplerian telescope (see this diagram) except with a curved metal mirror instead of the glass objective lens.

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Early Reflectors