每日彙整: 2016-10-12

樹莓派、樹莓派之學習、樹莓派之教育

光的世界︰【□○閱讀】反射式望遠鏡《四》

為著方便有興趣用 SymPy 作反射光學矩陣計算的讀者，在此引用Justin Peatross 和 Michael Ware 兩位先生所寫的 Optics Textbook 裡的範例，以為符號慣例之參考︰

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且藉此讓讀者可以再次欣賞他們的文筆風采。一探促使 ABCD 矩陣光學興起的『雷射共振腔』穩定性之問題︰

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至於將之用來分析典型的反射式望遠鏡︰

Gregorian

The Gregorian telescope, described by Scottish astronomer and mathematician James Gregory in his 1663 book Optica Promota, employs a concave secondary mirror that reflects the image back through a hole in the primary mirror. This produces an upright image, useful for terrestrial observations. Some small spotting scopes are still built this way. There are several large modern telescopes that use a Gregorian configuration such as the Vatican Advanced Technology Telescope, the Magellan telescopes, the Large Binocular Telescope, and the Giant Magellan Telescope.

gregorian_telescope-svg

Light path in a Gregorian telescope.

Newtonian

The Newtonian telescope was the first successful reflecting telescope, completed by Isaac Newton in 1668. It usually has a paraboloid primary mirror but at focal ratios of f/8 or longer a spherical primary mirror can be sufficient for high visual resolution. A flat secondary mirror reflects the light to a focal plane at the side of the top of the telescope tube. It is one of the simplest and least expensive designs for a given size of primary, and is popular with amateur telescope makers as a home-build project.

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Light path in a Newtonian telescope.

The Cassegrain design and its variations

The Cassegrain telescope (sometimes called the “Classic Cassegrain”) was first published in an 1672 design attributed to Laurent Cassegrain. It has a parabolic primary mirror, and a hyperbolic secondary mirror that reflects the light back down through a hole in the primary. Folding and diverging effect of the secondary creates a telescope with a long focal length while having a short tube length

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Light path in a Cassegrain telescope.

 

，由於光徑的圖示已經清楚明白，其餘則與折射式一般，茲不贅述的了！！