| | Telescope - Wikipedia, the free encyclopedia |
 | | Later, Johannes Kepler described the optics of lenses (see his books Astronomiae Pars Optica and Dioptrice), including a new kind of astronomical telescope with two convex lenses (a principle often called the Kepler telescope). |
| | Newtonian or reflecting telescopes employ the reflective properties of light, using a concave paraboic primary mirror to collect and focus incoming light onto a flat secondary (diagonal) mirror that in turn reflects the image through an opening at the side of the main tube and into the eyepiece. |
| | In this generation of telescopes, the mirror is usually very thin, and is kept in an optimal shape by an array of actuators (see active optics). |
| en.wikipedia.org /wiki/Telescope (2065 words) |
