光的世界︰【□○閱讀】折射式望遠鏡《四》

詩經‧國風‧召南‧小星

嘒彼小星,三五在東。
肅肅宵征,夙夜在公。
實命不同!

嘒彼小星,維參與昴。
肅肅宵征,抱衾與裯。
實命不猶!

晨見參昂,入秋矣。因何戴月披星,宵征也。或許詩人李白善解︰良人在公,拋衾與裯。的吧!!

子夜秋歌‧李白

長安一片月,萬戶搗衣聲。
秋風吹不盡,總是玉關情。
何日平胡虜,良人罷遠征。

現今城市光害嚴重,想見嘒彼小星,怕也不能的哩。既然 不得見,掛心星座運勢,又有何徵乎?秋分以過,寒露當令,北半天有

秋季四邊形

秋季四邊形,也稱飛馬座四邊形,是位於飛馬座的巨大四邊形,由室宿一(飛馬座α)、室宿二(飛馬座β)、壁宿一(飛馬座γ)和壁宿二仙女座α)四顆星組成,代表著飛馬的身體。

秋季四邊形觀察法

由於構成這個四邊形四個頂點的恆星均很亮,而內部幾乎沒有較亮的星,所以很容易辨別,通常與北斗七星作為在天空中定位的標誌。

constellation-art-pegasus

Stellarium中飛馬座的星圖,其中秋季四邊形為馬身處最亮的四顆星

 

1280px-pegasus_constellation_map

秋季四邊形星座圖

南半天有

秋季南三角

秋季南三角(又名秋季南天三角形南天大三角秋季大三角)是北半球的秋季時,由南天的三顆亮星所組的三角形,它們分別是南魚座北落師門鯨魚座土司空鳳凰座火鳥六[1][2]這三顆星分別是其所在星座最亮的恆星。

秋季南三角觀察法

秋季南三角位於著名的秋季四邊形以南,順著秋季四邊形往南找,便很容易觀測到。

scl

秋季南三角

 

何不趁機讀讀

Telescope Equations

Useful Formulas for Exploring the Night Sky

Index to This Page

Introduction
The Process
Terms & Symbols
Scope Equations
Special Cases

Introduction

Stars are so unimaginably far away that the light we receive from them arrives in rays that are perfectly parallel. Your eye is designed to focus these parallel rays to a point, allowing you to identify where the light is coming from.

A telescope, in its original configuration (refractor), consists of two lenses. The first one, the objective lens, collects light and focuses it to a point. (Note that the objective mirror in a reflecting telescope does exactly the same thing.) The second lens, the eyepiece, catches the light as it diverges away from the focal point and bends it back to parallel rays, so your eye can re-focus it to a point.

Notice how the telescope has taken all the light passing through the objective lens and compressed it down to a column of light that will pass through the pupil of the eye. This is one of the three major tasks of the telescope, the full list being:

  • Collect way more light than your eye can, to make a bright image
  • Resolve more detail in the image than your eye can without assistance
  • Magnify the image so you can see the additional detail

The equations on this page permit you to find just exactly how well the telescope will perform these tasks, and along the way I also show how the tasks are accomplished, by explaining both the theory and the practice. We will be talking specifically about visual observing through the telescope � how the telescope and your eye work together. Understanding photography starts with understanding these ideas, and here we are going to stick to visual observation.

CAUTION – telescope manufacturers will often advertise the magnification of the scope, and give really big, impressive numbers. The problem is that the number is essentially meaningless.

The magnification of a telescope is a combined function of the scope and the eyepiece that is used, so the user can set the magnification to almost any arbitrary value by selecting a suitable eyepiece. Whether the resulting image is clear, or barely visible, depends on other properties of the telescope. Therefore the magnification is not the most important measure of a telescope.

What actually is the most important measure is the diameter of the objective, or more simply the scope diameter, because that determines both the resolving power (the smallest detail you can see) and the light-gathering power (the faintest objects you can see). How the scope diameter determines the performance of your telescope is explained through the equations below.

 

Tutorial Presentation

Tutorial PowerPoint (2010 version)
Presentation of the Telescope Equations

This is how I teach the equations. Note that the full explanation for each slide is in the notes.
Updated 10 Nov 2012.

PowerPoint 97-2003 version Presentation of the Telescope Equations


Go To Stargazing Page


Thanks for Visiting!

Questions

Your questions and comments regarding this page are welcome. You can e-mail Randy Culp for inquiries, suggestions, new ideas or just to chat.
Updated 16 November 2012

 

,然後拎著望遠鏡

509_p_1440219213740

 

,足步鄉野和山丘,親探星星的故鄉☆★

 

 

 

 

 

 

 

 

 

 

光的世界︰【□○閱讀】折射式望遠鏡《三》

不同領域裡看似無關之問題,如果它們的數學關係式卻相同,或許彼此有更深之聯繫。值得類推比擬,用系統論的觀點一探它的原由 ,可能不期而遇發生跨學科之理解。約莫兩年前,我們談過一個叫『交叉梯子』的幾何學問題︰

559px-CrossedLadders.svgCrossedLaddersProblem_1000

CrossedLaddersProblem2_800

作者不知從何時起網路上開始流傳了一個『交叉梯子之問題』 Crossed ladders problem,根據『 Wolfram‧mathworld』的索引 ,它來自於

Gardner, M. Mathematical Circus: More Puzzles, Games, Paradoxes and Other Mathematical Entertainments from Scientific American. New York: Knopf, pp. 62-64, 1979.

這本書。為什麼它又被稱之為『迷惑‧難題』 puzzle 的呢?假使你知道『巷子』中兩根斜擺的『梯子』的長度是 a,b,你也知道它的『交叉點』距地的『高度』是 h,那麼你能不能算出『巷寬w 的呢?

由 於 h \parallel h_1h \parallel h_2,可以得到 \frac{d_2}{d} = \frac{h}{h_1}\frac{d_1}{d} = \frac{h}{h_2}。然而 d_1 + d_2 = d = \left( \frac{h}{h_2} \right) d + \left( \frac{h}{h_1} \right) d,化簡後得到 \frac{1}{h_1} + \frac{1}{h_2}  = \frac{1}{h},這三者竟然滿足這個『不預期』之『關係式』,而且不見 d 的蹤影了 。假設 h_1 的梯子長 l_1h_2 的梯子長 l_2,由『畢氏定理』 可以得到 l_1^2 + d^2  = h_1^2l_2^2 + d^2  = h_2^2,所以 l_1^2 - l_2^2 = h_1^2 - h_2^2 = (h_1 + h_2) \cdot (h_1 - h_2),因此 {\left[ l_1^2 - l_2^2  \right]}^2 = {(h_1 + h_2)}^2 \cdot {(h_1 - h_2)}^2
= {(h_1 + h_2)}^2 \cdot {\left[ {(h_1 + h_2)}^2 - 4 h_1 h_2 \right] },由於 \frac{1}{h_1} + \frac{1}{h_2}  = \frac{1}{h},因此 h_1h_2 = (h_1+h_2)h,將之代入上式得到
= {(h_1 + h_2)}^2 \cdot {\left[ {(h_1 + h_2)}^2 - 4 (h_1+h_2)h \right] }

。如果我們仔細考察下面的方程式

{\left[ l_1^2 - l_2^2  \right]}^2 =  {(h_1 + h_2)}^2 \cdot {\left[ {(h_1 + h_2)}^2 - 4 (h_1+h_2)h \right] }

,『左邊項』為『已知量』,『右邊項』是『未知數h_1+h_2 的『方程式』。假設 l_1 > l_2,如果我們定義

c = \frac{4 h}{\sqrt{l_1^2 - l_2^2}}x = \frac{h_1+h_2}{\sqrt{l_1^2 - l_2^2}}

, 可以將之化簡為

x^3(x - c) - 1 = 0

,總是不見『巷寬d 的『蹤影』,所以方說令人『迷惑』的啊!竟然得要『求解』四次方程式,因此才是個『難題』的吧!更不要講它還能夠有全『整數解』,舉例來說,(l_1, l_2, h, h_1, h_2, d_1, d_2, d) = (119, 70, 30, 105, 42, 40, 16, 56),果然是奇也怪哉!!

假使我們已經解得了 x_{\lambda},那麼要怎們求出『巷寬d 的呢?我們還得解下面的方程式?? 假設 \alpha = \sqrt{l_1^2 - l_2^2} x_{\lambda}

h_1 + h_2 = \alpha

h_1 \cdot h_2 = \alpha h

,用二次方程式的『公式解』可以得到

h_1 = \frac{\alpha \pm \sqrt{{\alpha}^2 - 4 \alpha h}}{2}

h_2 = \frac{\alpha \mp \sqrt{{\alpha}^2 - 4 \alpha h}}{2}

再 由,l_1^2 + l_2^2 = (h_1^2 + d^2) + (h_2^2 + d^2),因此 d = \sqrt{\frac{(l_1^2 + l_2^2) - (h_1^2 + h_2^2)}{2},因為 h_1^2 + h_2^2 = {(h_1+h_2)}^ 2 - 2 h_1 h_2 = {\alpha}^ 2 - 2 \alpha h,所以那個久違的『巷寬』就是 d = \sqrt{\frac{(l_1^2 + l_2^2) - ( {\alpha}^ 2 - 2 \alpha h)}{2}!!

有人問為什麼要『假設l_1 > l_2 的呢?由於那個『方程式』對於 h_1, h_2l_1, l_2 來講是『對稱的』,所以除非這兩者『相等』,否則『假設l_1 > l_2 只是方便論述而已,畢竟『根號』 內之數在此該是正的啊!再者當 l_1 = l_2 時,就有 {(\frac{l_1}{2})}^2 + h^2 = {(\frac{d}{2})}^2 的關係存在,就可以直接求得 d = \sqrt{l_1^2 + 4 h^2} 的了!如此根本不需要解那個四次方程式的吧!!

如果從『直覺上』來講,假使當 h_2 = \delta h_2 \approx 0,此時 h = \delta h \approx 0,那麼我們能夠求得 \frac{\delta h}{\delta h_2} 之『極限值』 的嗎?因為這時 l_2 \approx d,因此c = \frac{4 h}{\sqrt{l_1^2 - l_2^2}} \approx \frac{4 \delta h}{\sqrt{l_1^2 - d^2}} \approx 0,所以那個四次方程式就變成了 x^3(x - c) -1 =0 \Longrightarrow  x^4 - 1 \approx 0,它有四個解 \pm 1, \pm \sqrt{-1},於是 \alpha = \sqrt{l_1^2 - l_2^2} x_{\lambda} \approx \sqrt{l_1^2 - d^2},由於 h_1 \delta h_2 = \alpha \delta h,故得 \frac{\delta h}{\delta h_2} = \frac{h_1}{\alpha} \approx \frac{h_1}{\sqrt{l_1^2 - d^2}} \approx 1

事實上,即使\angle BAC\angle DCA不是『直角』,依然是 \frac{1}{\overline{AB}} + \frac{1}{\overline{CD}} = \frac{1}{\overline{EF} }。在它們是『直角』時,甚至可以得到 \angle BFE = \angle DFE,如果將它想像成『入射角』等於『反射角』,從 B 點發出的光線,將於 F 點反射到 D 點上。

CrossedLaddersTheorem_1000

許多看似『無關』的『知識』片段,往往具有『內在』的『肌理』關係,就此觀之,『學習』一事常在『發現』這個『關係』,以及『貫通』現象之間內在的『聯繫』的啊!!

摘自《【Sonic π】電路學之補充《四》無窮小算術‧中下中‧下

 

不知如今讀來,是否心有戚戚焉!『幾何光學』之『幾何』何為耶 ?若將

光的軌跡 〒 梯子長度

光程 〒 巷寬

物距 d_o 〒 左梯 h_1

像距 d_i 〒 右梯 h_2

焦距 f 〒 兩梯之交叉點高 h

對應起來,那麼『等光程原理』就是『同一巷子』的乎!☆

如是在等光程下,是否

\frac{\delta f}{\delta d_i}  \approx 1 的呢?★

 

最後且借先前提及之 OpticalRayTracer 軟體工具,追跡光程行徑,假虛擬透鏡實驗折射式望遠鏡之成像控制的穩定性。權當補筆之說而已。

【理想望遠鏡模型 ε=0】

%e6%9c%9b%e9%81%a0%e9%8f%a1%e4%b8%80

 

【ε<0】

%e6%9c%9b%e9%81%a0%e9%8f%a1%e4%ba%8c

 

【ε>0】

%e6%9c%9b%e9%81%a0%e9%8f%a1%e4%b8%89

 

 

 

 

 

 

 

 

 

 

光的世界︰【□○閱讀】折射式望遠鏡《二》

玄疑令人著迷,怪誕使人好奇!如果用科學來解釋玄疑怪誕,其實很無趣?因為總得有個『假說』,希望可被『證偽』的哩??

無論最新之貴州的

500米口徑球面無線電望遠鏡

500米口徑球面無線電望遠鏡英語:Five hundred meter Aperture Spherical Telescope,簡稱FAST)是中國的一座無線電望遠鏡焦比達0.467。FAST位於貴州省平塘縣克度鎮大窩凼窪地,利用喀斯特窪地的地勢而建。FAST已於2008年12月26日奠基,在2016年9月25日開光[4][5]。建成後超越阿雷西博天文台,成為世界上最大的單面口徑球面無線電望遠鏡[6],預計投資7億元人民幣[7][8]

多大多貴,恐怕很難尋找、證實有沒有『外星人』的吧!!然而那蘇軾曾寫道??

遊金山寺

我家江水初發源,宦遊直送江入海。
聞道潮頭一丈高,天寒尚有沙塵在。
中泠南畔石盤陀,古來出沒隨濤波。
試登絕頂望鄉國,江南江北青山多。
羈愁畏晚尋歸楫,山僧苦留看落日。
微風萬頃靴文細,斷霞半空魚尾赤。
是時江月初生魄,二更月落天深黑。
江心似有炬火明,飛燄照山棲鳥驚。
悵然歸臥心莫識,非鬼非人竟何物。
江山如此不歸山,江神見怪警我頑。
我謝江神豈得已,有田不歸如江水。

 

未免於爭議能或不能之紛紛擾擾,就此舉出

月球

月球,俗稱月亮,古時又稱太陰玄兔[5],是地球唯一的天然衛星[nb 4][6],並且是太陽系第五大的衛星。月球的直徑是地球的四分之一,質量是地球的1/81,相對於所環繞的行星,它是質量最大的衛星,也是太陽系內密度第二高的衛星,僅次於木衛一

一般認為月亮形成於約45億年前,地球出現後的不長時間。有關它的起源有幾種假說;最被普遍認可的解釋是,它形成於地球與火星般大小的天體-「忒伊亞」之間一次巨大撞擊所產生的碎片。

如何『形成』之

大碰撞說

大碰撞說英語:Giant impact hypothesis),是一種解釋月球形成原因及過程的假說。該假說認為在大約45億年前(或太陽系形成後約2,000萬到1億年前的冥古宙[1]),地球和一顆火星大小的天體發生撞擊,殘留的碎片形成了月球。這顆撞擊地球的天體被稱為忒伊亞(Theia),這名字是希臘泰坦神話裡月神塞勒涅的母親之名。

大碰撞說是目前最受青睞的科學假說[1],支持的證據包括:地球自轉和月球公轉方向相同[2]、月球曾擁有熔融態的表面、月球擁有較小的鐵核且其密度比地球低、由其他行星系統發生類似碰撞所得到的證據(即導致岩屑盤)、符合主流的太陽系形成理論。最後,月球和地球岩石擁有的穩定同位素比率是相同的,這意味著相同的起源。[3]

儘管為目前最佳的月球形成假說,大碰撞說仍存在一些缺陷[4]。理論上,大碰撞產生的高溫會形成全球性的岩漿海,然而,沒有證據能證明較重的物質因此沈入地函。目前,沒有模型能對於從發生大碰撞到形成月球的過程作出完美解釋。其他問題包括,月球何時開始失去揮發性物質、以及同樣發生過碰撞的金星為何沒有衛星。

為例。再次強調科學的理論,不只想說明『已知』之事實★還更想推演『未知』的現象也☆故可以『事實現象』決疑除怪耶!!??

因此柔情似水 ䷜ 的月亮,為何有此

表面地質

月球是地球的同步自轉衛星,它繞軸自轉的週期與繞地球的公轉周期是相同的,這使得它幾乎永遠以同一面朝向地球。它之前以較快的速度旋轉,在後來由於地球產生潮汐摩擦,讓其自轉速度減慢,直到最後以同一面持續面對地球,即潮汐鎖定[38]。我們將月球朝向地球的一面被稱為正面,而相對的另一面則稱為背面,背面通常也稱為”暗面”,但是事實上它如同正面一樣會被照亮。當月相為新月時,我們看到月球的正面是黑暗的,而月球的背面則被太陽照亮[39]

科學家曾經使用雷射測高儀立體影像分析對月球表面的地形進行測量[40]。月球表面最明顯的地形特徵是位於背面的巨大撞擊坑南極-艾托肯盆地,其直徑有2,240公里,是月球上最大的隕石坑,也是太陽系中已知最大的[41][42]。它的底部是月球上海拔最低的地方,深度達到13公里[41][43]。而月球海拔最高的地點則正好就在它的東南方,有人認為這個區域是造成南極-艾托肯盆地的撞擊所形成的隆起[44]。月球上的其它大撞擊盆地,如雨海澄海危海史密斯海東方海等,也都擁有低海拔的區域和高聳的邊緣[41]。月球背面的平均高度比正面高1.9公里[34]

phase-180

月球正面

far-side-phase-180

月球背面,和正面的不同之處在於缺少黑暗的月海[37]

以及那麼多的

撞擊坑

另一個會影響月球表面地形的主要地質事件是撞擊坑[56]小行星彗星撞擊月球表面時都會形成隕石坑,現在估計單在月球正面直徑大於1公里的隕石坑就大約有300,000個[57],其中有些隕石坑以知名的學者、科學家、藝術家和探險家的名字命名[58]月球地質年代是根據月面上的重大隕石撞擊事件進行分界,包括在酒海雨海東方海等的撞擊事件。這些撞擊事件的結構特徵是產生多層物質隆起的環,通常是由數百至數千公里直徑的圍裙狀噴發物沉積形成一個區域性的地層視界[59]。由於月球沒有大氣層、天氣變化,在最近幾十億年也沒有地質活動,大部分環形山都保存得很完好。雖然有幾個多環盆地明顯的已經很久遠,它們還是能用於分派相對的年齡。由於撞擊坑是以恆定的速率累積,計算單位面積內的撞擊坑數目可以用來估計表面的年齡[59]阿波羅任務收集撞擊熔化的岩石以輻射測定年齡,群集在38億和41億年的年齡:這已被用來建議撞擊的後期重轟炸期[60]

覆蓋在月球地殼上的是高度粉碎的(碎裂成更小的顆粒)和撞擊園藝下的表面層稱為風化層,是由撞擊過程形成的。最細微的風化層,是二氧化矽月球土壤玻璃狀物體,有著像雪一樣的紋理和聞起來像用過的火藥[61]。較老的風化層表面一般比年輕的表面厚;在高地的厚度在10-20米之間,在海的厚度則是3-5米。[62] 在細緻的粉碎風化層下面是「粗風化層(megaregolith)」,厚達數公里高度碎裂的基岩[63]

1024px-moon_south_pole

克萊門汀號拍攝的月球南極馬賽克圖:請注意極地的永久陰影。

,不會被描述成︰替大地之母 ䷁ 蓋亞檔災殃的乎??!!

如是觀之太陽系 ䷀ 的『穩定性』,不過講其對『撞擊』之『靈敏度 』不高矣︰

假使說一個系統 S 很『靈敏』 sensitive ,是講當系統的『輸入』 I 有一點『變化』 \Delta I ,系統之『輸出』 O ,產生很大的『改變』 \Delta O ,也就是說

\frac{\Delta O}{\Delta I} 的『比值』很大。

然而『靈敏度』 Sensitivity 一詞,用於不同的領域、場合,常帶著點不同的意味,遇到此詞時,避免望文生義。如果將『靈敏度』用於『量測儀器』,通常是指儀表對於『輸入變化』的『分辨能力』 ,一般用著某種 \frac{\Delta O}{\Delta I} 之『比值』來表示。

Rayleigh_criterion_plot
瑞利準則

比方說 一個光學儀器的『角分辨度』 Angular resolution

\theta \approx \sin \theta = 1.220 \frac{\lambda}{2 R}

表示要是透鏡和兩個物件之間的夾角少於 \theta ,透鏡的觀察者便無法分辨出有兩個物件。不要以為『分辨能力』愈『』,就一定是愈『』,通常顯微鏡的放大倍數『越高』,可能操作上也『越難』 。設使每個人的『視力』都能睹『秋毫之末』,怕世間『』『』的『標準』會變的吧?難想像會發明『幾 K 』的電視的哩!

『量測裝置』 S_M 是一個『物理系統』,待量測『自然萬象』 S_P 也是一個『物理系統』,彼此『交互作用』 ── 能量和物質轉化與交換 ──,得到『度量』之數據,『測知』現象系統的『狀態』。自考察『現象』之『狀態』上來講,假使從『微觀上』將之當成由『粒子系統』所構成,或許可以用『相空間』之『相圖』來觀察︰

300px-Focal_stability

430px-Pendulum_Phase_Portrait

Hamiltonian_flow_classical

340px-Limitcycle.svg

一個質量 m 物體,初始位置在 x_0,初始速度為 v_0 ,在 x 軸上運動,依據牛頓的第二運動定律,它的運動滿足一個二階微分方程式︰

\vec{F} = m \cdot \vec{a} = m \cdot \frac{d^2 x}{dt^2}

一般而言,除了一些特殊的力 \vec{F} 的形式,比方說簡諧運動之線性彈力 F = k \cdot x,微分方程式很難有『確解』,大概都得用『數值分析』的方式求解。那麼有沒有另一種運動描述辦法的呢?龐加萊和玻爾茲曼 Boltzmann 等人發展了『相空間』phase space 的想法,因為物體一旦給定了初始位置與初始速度── 一般使用動量 p = m \cdot v ──,它的運動軌跡就由牛頓的第二運動定律所確定,相空間是一個 (位置,動量) 所構成的座標系,這樣該物體的運動軌跡就畫出了相空間裡的一條線 ── 叫做相圖 phase diagram ──。一般這條曲線不會『自相交』,因為相交代表有不同的運動軌跡可以選擇,所以一旦相交會就只能是一種『週期運動』。龐加萊在研究三體問題的相圖時,卻發現只要『初始點』──  位置或動量 ──,極微小的變化,相圖就發生很大的改變,這種『敏感性』可能導致系統的『不可預測性』或是『不穩定性』。那我們的太陽系是穩定的嗎??

─── 摘自《失之豪釐,差以千里!!《中》

 

因為望遠鏡不同圖示、說明之差異︰

The Astronomical Telescope

The astronomical telescope makes use of two positive lenses: the objective, which forms the image of a distant object at its focal length, and the eyepiece, which acts as a simple magnifier with which to view the image formed by the objective. Its length is equal to the sum of the focal lengths of the objective and eyepiece, and its angular magnification is -fo /fe , giving an inverted image.

The astronomical telescope can be used for terrestrial viewing, but seeing the image upside down is a definite inconvenience. Viewing stars upside down is no problem. Another inconvenience for terrestrial viewing is the length of the astronomical telescope, equal to the sum of the focal lengths of the objective and eyepiece lenses. A shorter telescope with upright viewing is the Galilean telescope.

Galilean Telescope

The Galilean or terrestrial telescope uses a positive objective and a negative eyepiece. It gives erect images and is shorter than the astronomical telescope with the same power. It’s angular magnification is -fo/fe .

The image below shows parallel rays from two helium-neon lasers passing through a Galilean telescope made from an objective with f=30cm and an eyepiece with f=-10cm.

With the lenses placed 20 cm = fo+fe apart, the parallel input rays are rendered parallel again by the eyepiece lens, giving an image at infinity. This shows one of the uses of Galilean telescopes. It is useful as a collimator that takes a large beam of parallel light and reduces the size of the beam, keeping the rays parallel. The angular magnification of this Galilean telescope is 3. The beams of the helium-neon lasers were made visible with a spray can of artificial smoke.

───

2:黃福坤(研究所)張貼:2006-10-22 13:02:58:

一旦你清楚瞭解了放大鏡的工作原理 之後要理解 望遠鏡或顯微鏡就很簡單了

放大鏡藉由將物體放在焦距內一點點 產生虛像的視角放大 讓眼睛看到更大的影像於視網膜上

若是有物體位於很遠的地方 我們知道 加上透鏡後物體會呈現於透鏡的焦點附近!
但是影像會很小 因此可以利用放大鏡的效果將其放大
若是我們在物體成像位置後放置另一個透鏡 且透鏡焦距就是該像與透鏡的距離(稍大一點)
於是 很遠處的物體所形成的像 被第二個透鏡以視角放大的方式讓我們看到 就是 望遠鏡了!

如下圖

 

在此假借『微擾理論』︰

Perturbation theory

Perturbation theory comprises mathematical methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middle step that breaks the problem into “solvable” and “perturbation” parts.[1] Perturbation theory is applicable if the problem at hand cannot be solved exactly, but can be formulated by adding a “small” term to the mathematical description of the exactly solvable problem.

Perturbation theory leads to an expression for the desired solution in terms of a formal power series in some “small” parameter – known as a perturbation series – that quantifies the deviation from the exactly solvable problem. The leading term in this power series is the solution of the exactly solvable problem, while further terms describe the deviation in the solution, due to the deviation from the initial problem. Formally, we have for the approximation to the full solution A, a series in the small parameter (here called ε), like the following:

A=A_{0}+\varepsilon ^{1}A_{1}+\varepsilon ^{2}A_{2}+\cdots

In this example, A0 would be the known solution to the exactly solvable initial problem and A1, A2, … represent the higher-order terms which may be found iteratively by some systematic procedure. For small ε these higher-order terms in the series become successively smaller.

An approximate “perturbation solution” is obtained by truncating the series, usually by keeping only the first two terms, the initial solution and the “first-order” perturbation correction

A\approx A_{0}+\varepsilon A_{1}~.

………

History

Perturbation theory was first devised to solve otherwise intractable problems in the calculation of the motions of planets in the solar system. The gradually increasing accuracy of astronomical observations led to incremental demands in the accuracy of solutions to Newton’s gravitational equations, which led several notable 18th and 19th century mathematicians to extend and generalize the methods of perturbation theory. These well-developed perturbation methods were adopted and adapted to solve new problems arising during the development of Quantum Mechanics in 20th century atomic and subatomic physics.

Beginnings in the study of planetary motion

Since the planets are very remote from each other, and since their mass is small as compared to the mass of the Sun, the gravitational forces between the planets can be neglected, and the planetary motion is considered, to a first approximation, as taking place along Kepler’s orbits, which are defined by the equations of the two-body problem, the two bodies being the planet and the Sun.[3]

Since astronomic data came to be known with much greater accuracy, it became necessary to consider how the motion of a planet around the Sun is affected by other planets. This was the origin of the three-body problem; thus, in studying the system Moon–Earth–Sun the mass ratio between the Moon and the Earth was chosen as the small parameter. Lagrange and Laplace were the first to advance the view that the constants which describe the motion of a planet around the Sun are “perturbed” , as it were, by the motion of other planets and vary as a function of time; hence the name “perturbation theory” .[3]

Perturbation theory was investigated by the classical scholars — Laplace, Poisson, Gauss — as a result of which the computations could be performed with a very high accuracy. The discovery of the planet Neptune in 1848 by Urbain Le Verrier, based on the deviations in motion of the planet Uranus (he sent the coordinates to Johann Gottfried Galle who successfully observed Neptune through his telescope), represented a triumph of perturbation theory.[3]

Rise of understanding of chaotic systems

The development of basic perturbation theory for differential equations was fairly complete by the middle of the 19th century. It was at that time that Charles-Eugène Delaunay was studying the perturbative expansion for the Earth-Moon-Sun system, and discovered the so-called “problem of small denominators”.[citation needed] Here, the denominator appearing in the n-th term of the perturbative expansion could become arbitrarily small, causing the n-th correction to be as large or larger than the first-order correction.

At the turn of the 20th century, this problem led Henri Poincaré to make one of the first deductions of the existence of chaos,[citation needed] and what is poetically called the “butterfly effect”:[citation needed] that even a very small perturbation can ultimately have a very large effect on non-dissipative or “friction-free” dynamic systems.

A partial resolution of the small-divisor problem was given by the statement of the KAM theorem in 1954. Developed by Andrey Kolmogorov, Vladimir Arnold and Jürgen Moser, this theorem stated the conditions under which a system of partial differential equations will have only mildly chaotic behaviour under small perturbations.

 

之名舖成一番,讀者但求其實的了。

【僅供參考】

pi@raspberrypi:~ $ ipython3
Python 3.4.2 (default, Oct 19 2014, 13:31:11) 
Type "copyright", "credits" or "license" for more information.

IPython 2.3.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: from sympy import *

In [2]: from sympy.physics.optics import FreeSpace, FlatRefraction, ThinLens, GeometricRay, CurvedRefraction, RayTransferMatrix

In [3]: init_printing()

In [4]: fo, ε, fe, X, I = symbols('fo, ε, fe, X, I')

In [5]: 理想模型 = ThinLens(fe) * FreeSpace(fe + fo) * ThinLens(fo)

In [6]: 理想模型
Out[6]: 
⎡       fe + fo                 ⎤
⎢   1 - ───────        fe + fo  ⎥
⎢          fo                   ⎥
⎢                               ⎥
⎢      fe + fo                  ⎥
⎢  1 - ───────                  ⎥
⎢         fe     1       fe + fo⎥
⎢- ─────────── - ──  1 - ───────⎥
⎣       fo       fe         fe  ⎦

In [7]: 理想模型.A.simplify()
Out[7]: 
-fe 
────
 fo 

In [8]: 理想模型.C.simplify()
Out[8]: 0

In [9]: 理想模型.D.simplify()
Out[9]: 
-fo 
────
 fe 

In [10]: 理想模型 = RayTransferMatrix(-fe/fo, fe+fo, 0, -fo/fe)

In [11]: 理想模型成像 = FreeSpace(I) * 理想模型 * FreeSpace(X)

In [12]: 理想模型成像
Out[12]: 
⎡-fe     I⋅fo   X⋅fe          ⎤
⎢────  - ──── - ──── + fe + fo⎥
⎢ fo      fe     fo           ⎥
⎢                             ⎥
⎢               -fo           ⎥
⎢ 0             ────          ⎥
⎣                fe           ⎦

In [13]: 理想模型成像物距 = solve(理想模型成像.B, X)

In [14]: 理想模型成像物距
Out[14]: 
⎡   ⎛          2        ⎞⎤
⎢fo⋅⎝-I⋅fo + fe  + fe⋅fo⎠⎥
⎢────────────────────────⎥
⎢            2           ⎥
⎣          fe            ⎦

In [15]: 實物望遠鏡 = ThinLens(fe) * FreeSpace(fe + fo + ε) * ThinLens(fo)

In [16]: 實物望遠鏡
Out[16]: 
⎡       fe + fo + ε                     ⎤
⎢   1 - ───────────        fe + fo + ε  ⎥
⎢            fo                         ⎥
⎢                                       ⎥
⎢      fe + fo + ε                      ⎥
⎢  1 - ───────────                      ⎥
⎢           fe       1       fe + fo + ε⎥
⎢- ─────────────── - ──  1 - ───────────⎥
⎣         fo         fe           fe    ⎦

In [17]: 實物望遠鏡.A.simplify()
Out[17]: 
-(fe + ε) 
──────────
    fo    

In [18]: 實物望遠鏡.C.simplify()
Out[18]: 
  ε  
─────
fe⋅fo

In [19]: 實物望遠鏡.D.simplify()
Out[19]: 
-(fo + ε) 
──────────
    fe    

In [20]: 實物望遠鏡 = RayTransferMatrix(-(fe+ε)/fo, fe+fo+ε, ε/(fe*fo), -(fo+ε)/fe)

In [21]: 誤差矩陣 = 實物望遠鏡 - 理想模型

In [22]: 誤差矩陣
Out[22]: 
⎡fe   -fe - ε              ⎤
⎢── + ───────       ε      ⎥
⎢fo      fo                ⎥
⎢                          ⎥
⎢     ε        fo   -fo - ε⎥
⎢   ─────      ── + ───────⎥
⎣   fe⋅fo      fe      fe  ⎦

In [23]: 誤差矩陣.A.simplify()
Out[23]: 
-ε 
───
 fo

In [24]: 誤差矩陣.D.simplify()
Out[24]: 
-ε 
───
 fe

In [25]: 微擾矩陣 = ε * RayTransferMatrix(-1/fo, 1, 1/(fe*fo), -1/fe)

In [26]: 微擾矩陣
Out[26]: 
⎡ -ε       ⎤
⎢ ───    ε ⎥
⎢  fo      ⎥
⎢          ⎥
⎢  ε    -ε ⎥
⎢─────  ───⎥
⎣fe⋅fo   fe⎦

In [27]: 微擾成像 = FreeSpace(I) * 微擾矩陣 * FreeSpace(X)

In [28]: 微擾成像
Out[28]: 
⎡ I⋅ε    ε     I⋅ε     ⎛ I⋅ε    ε ⎞    ⎤
⎢───── - ──  - ─── + X⋅⎜───── - ──⎟ + ε⎥
⎢fe⋅fo   fo     fe     ⎝fe⋅fo   fo⎠    ⎥
⎢                                      ⎥
⎢    ε                X⋅ε    ε         ⎥
⎢  ─────             ───── - ──        ⎥
⎣  fe⋅fo             fe⋅fo   fe        ⎦

In [29]: solve(微擾成像.B, X)
Out[29]: [fo]

In [30]: 實物望遠鏡成像 = FreeSpace(I) * (理想模型 + 微擾矩陣) * FreeSpace(X)

In [31]: 實物望遠鏡成像
Out[31]: 
⎡ I⋅ε    fe   ε     ⎛  fo   ε ⎞     ⎛ I⋅ε    fe   ε ⎞              ⎤
⎢───── - ── - ──  I⋅⎜- ── - ──⎟ + X⋅⎜───── - ── - ──⎟ + fe + fo + ε⎥
⎢fe⋅fo   fo   fo    ⎝  fe   fe⎠     ⎝fe⋅fo   fo   fo⎠              ⎥
⎢                                                                  ⎥
⎢       ε                           X⋅ε    fo   ε                  ⎥
⎢     ─────                        ───── - ── - ──                 ⎥
⎣     fe⋅fo                        fe⋅fo   fe   fe                 ⎦

In [32]: 實物望遠鏡成像物距 = solve(實物望遠鏡成像.B, X)

In [33]: 實物望遠鏡成像物距
Out[33]: 
⎡   ⎛                2               ⎞⎤
⎢fo⋅⎝-I⋅fo - I⋅ε + fe  + fe⋅fo + fe⋅ε⎠⎥
⎢─────────────────────────────────────⎥
⎢                   2                 ⎥
⎣          -I⋅ε + fe  + fe⋅ε          ⎦

In [34]: 

 

 

 

 

 

 

 

 

 

 

 

光的世界︰【□○閱讀】折射式望遠鏡《一》

武陵春圖卷
一一三四年‧紹興四年冬十月
避亂金華

李清照‧武陵春

風住塵香花已盡,日晚倦梳頭。
物是人非事事休,欲語淚先流。
聞說雙溪春尚好,也擬泛輕舟。
只恐雙溪舴艋舟,載不動許多

一九四零年,美國哲學家莫蒂默‧傑爾姆‧阿德勒 Mortimer Jerome Adler 寫了一本《如何閱讀一本書》的書。其後於一九七二年,美國哥倫比亞大學的教授查爾斯‧范多倫 Charles Van Doren 重新修訂。這本書主要論述如何『通過閱讀』增進『理解力』。《如何閱讀一本書》將閱讀分做四個層次『基礎閱讀』、『檢視閱讀』、『分析閱讀』和『主題閱讀』。並在書後推薦了一系列的『經典名著』。『 目的』是強調閱讀是一種『自主活動』。

───  摘自《如何閱讀□○??

 

閱讀最重要的事就是學會閱讀的方法。如是方能自主學習有興趣的知識,得到讀書的樂趣。因此在讀過一系列文本後,相信讀者已能輕輕鬆鬆瀏覽維基百科詞條︰

Refracting telescope

A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses. Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes the refracting telescope has been superseded by the reflecting telescope which allows larger apertures. A refractor’s magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece.[1]

Refracting telescope designs

All refracting telescopes use the same principles. The combination of an objective lens 1 and some type of eyepiece 2 is used to gather more light than the human eye is able to collect on its own, focus it 5, and present the viewer with a brighter, clearer, and magnified virtual image 6.

The objective in a refracting telescope refracts or bends light. This refraction causes parallel light rays to converge at a focal point; while those not parallel converge upon a focal plane. The telescope converts a bundle of parallel rays to make an angle α, with the optical axis to a second parallel bundle with angle β. The ratio β/α is called the angular magnification. It equals the ratio between the retinal image sizes obtained with and without the telescope.[4]

Refracting telescopes can come in many different configurations to correct for image orientation and types of aberration. Because the image was formed by the bending of light, or refraction, these telescopes are called refracting telescopes or refractors.

kepschem

Galileo’s telescope

The design Galileo Galilei used in 1609 is commonly called a Galilean telescope. It used a convergent (plano-convex) objective lens and a divergent (plano-concave) eyepiece lens (Galileo, 1610).[6] A Galilean telescope, because the design has no intermediary focus, results in a non-inverted and upright image.

Galileo’s best telescope magnified objects about 30 times. Because of flaws in its design, such as the shape of the lens and the narrow field of view, the images were blurry and distorted. Despite these flaws, the telescope was still good enough for Galileo to explore the sky. The Galilean telescope could view the phases of Venus, and was able to see craters on the Moon and four moons orbiting Jupiter.

Parallel rays of light from a distant object (y) would be brought to a focus in the focal plane of the objective lens (F′ L1 / y′). The (diverging) eyepiece (L2) lens intercepts these rays and renders them parallel once more. Non-parallel rays of light from the object traveling at an angle α1 to the optical axis travel at a larger angle (α2 > α1) after they passed through the eyepiece. This leads to an increase in the apparent angular size and is responsible for the perceived magnification.

The final image (y″) is a virtual image, located at infinity and is the same way up as the object.

galileantelescope

Optical diagram of Galilean telescope y – Distant object ; y′ – Real image from objective ; y″ – Magnified virtual image from eyepiece ; D – Entrance pupil diameter ; d – Virtual exit pupil diameter ; L1 – Objective lens ; L2 – Eyepiece lens e – Virtual exit pupil – Telescope equals [5]

 

解釋折射式望遠鏡成像原理的吧☆

遠物→do = do’ – f1→F1面→望遠鏡→F2面→z=z’-f2→眼→e→成像

pi@raspberrypi:~ ipython3 Python 3.4.2 (default, Oct 19 2014, 13:31:11)  Type "copyright", "credits" or "license" for more information.  IPython 2.3.0 -- An enhanced Interactive Python. ?         -> Introduction and overview of IPython's features. %quickref -> Quick reference. help      -> Python's own help system. object?   -> Details about 'object', use 'object??' for extra details.  In [1]: from sympy import *  In [2]: from sympy.physics.optics import FreeSpace, FlatRefraction, ThinLens, GeometricRay, CurvedRefraction, RayTransferMatrix  In [3]: init_printing()  In [4]: do, f1, f2, z, f, e = symbols('do, f1, f2, z, f, e')  In [5]: 平行光分解變換 = RayTransferMatrix(- f2/f1, f1+f2, 0, -f1/f2)  In [6]: F1F2面參考系 = FreeSpace(f2) * 平行光分解變換 * FreeSpace(f1)  In [7]: F1F2面參考系 Out[7]:  ⎡-f₂       ⎤ ⎢────   0  ⎥ ⎢ f₁       ⎥ ⎢          ⎥ ⎢      -f₁ ⎥ ⎢ 0    ────⎥ ⎣       f₂ ⎦  In [8]: F1F2面物距 = FreeSpace(do)  In [9]: F1F2面觀看距離Z = FreeSpace(z)  In [10]: 眼睛 = ThinLens(f)  In [11]: 成像 = FreeSpace(e)  In [12]: 光線追跡 = 成像 * 眼睛 * F1F2面觀看距離Z * F1F2面參考系 * F1F2面物距  In [13]: 光線追跡.B Out[13]:          ⎛  e    ⎞      ⎛      ⎛  e    ⎞⎞   do⋅f₂⋅⎜- ─ + 1⎟   f₁⋅⎜e + z⋅⎜- ─ + 1⎟⎟         ⎝  f    ⎠      ⎝      ⎝  f    ⎠⎠ - ─────────────── - ────────────────────          f₁                  f₂           In [14]: 成像條件 = solve(光線追跡.B.expand(), e)  In [15]: 1 / 成像條件[0] Out[15]:       2       2     2   do⋅f₂  - f⋅f₁  + f₁ ⋅z ──────────────────────     ⎛     2     2  ⎞     f⋅⎝do⋅f₂  + f₁ ⋅z⎠    In [16]:  </pre>    假設角放大率M = \frac{f_1}{f_2},那麼望遠鏡成像可以表示成 \frac{1}{e} = \frac{1}{f} - \frac{1}{\frac{d_o' - f_1}{M^2} + (z' -f_2)} }$ 。

 

 

 

 

 

 

 

 

 

 

 

 

光的世界︰【□○閱讀】平行光之疑惑

在《M♪o 之學習筆記本《丑》控制︰【紅火南】東籬南山》文本中

派生碼訊

丑 牛

陶淵明‧飲酒 其五

結盧在人境,面無車馬喧
問君何能爾,心遠地自偏
採菊東籬下,悠然見南山
山氣日夕佳,飛鳥相與還
此中有真意,欲辨以忘言。

紅火南︰ 鑽木取火,木雖燼,火可傳;思接千載,思愈,越益物。

派︰《思創》事物因何起?『傳記』長史一線牽,有心哉花花不發,無心插柳柳成蔭;心有靈犀一點通,窮經皓首難為功?若說到底︰真積力,久則入。人不能通,神來通!真情真事喜相逢!

碼 ︰無 習 。☿☹

行 ︰雖無有瑞士軍刀,何妨效法馬蓋仙,兩根母母線,一個『一千』導阻,玩個過癮︰☿☺!

訊 ︰ ☿ 山窮水盡疑無路,柳暗花明又一村。

 

我們談及了馬蓋仙

百戰天龍》(MacGyver)(港譯《玉面飛龍》),美國電視劇系列,最初是在1985年9月在美國廣播公司電視網播出的,一直到1992年中的一季才結束,全劇共有七季139集。

故事舞台遍及世界各地,然而實際都是在加州南部(第一季、第二季和第七季)與加拿大溫哥華周邊地區(第三季至第六季)拍攝 。雖然影集已經停播,但後來仍有兩部電視電影,分別是《馬蓋先奪寶奇謀[1](The Lost City of Atlantic)》和《馬蓋先橫掃千軍[2](Trail to Doomsday)》。影集及電影大致上的情節在於馬蓋先的冒險故事與化解危機。他從來不帶武器,只靠一把瑞士刀,他過人的智慧,利用身邊任何不起眼的物品來解決困難。馬蓋先有著廣泛的物理化學知識,還有一切能實行他的「馬蓋先主義(MacGyverism)」的東西。

 

此處以平行光,思無窮,鑽籬木取離火!得百戰天龍智慧之旨耶☆物理固非數學,當物理原理用數學式子表達時,數學之正確,或需物理的詮釋乎?論疑惑生之所焉★

若問焦、焦面

牛頓成像公式

之成像法則

x \cdot x' = {f_{eff}}^2

所說何事?不管 f_{eff} 是正或是負,  {f_{eff}}^2 都是正的也!如是對凸透鏡來講,無窮遠之物 x \to \infty ,將成像於後焦點之平面上 x' \to 0 。那麼對凹透鏡來說,分明數學式子一樣!!又怎麼能一樣的呢??假使知道凹透鏡的後焦距面在凹透鏡之前,前焦距面在凹透鏡之後 ,能否釋疑呢???當真成像還是在後焦距面上!!!

其實物理的基礎是現象事實,從幾何光學來談光行經透鏡時的現象 ,不過是光束之聚或散而已。事實與成不成像 ── 有人在看、相機在拍 ── 語意有差異矣。就像『照明

Lighting

Lighting or illumination is the deliberate use of light to achieve a practical or aesthetic effect. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting (using windows, skylights, or light shelves) is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.

Indoor lighting is usually accomplished using light fixtures, and is a key part of interior design. Lighting can also be an intrinsic component of landscape projects.

 

豈因為要成像嘛。而且見物攝影無非是見物之像而已。所以虛、實之名義,只是說︰透鏡後光線聚焦稱實像;若是透鏡後光線往前之延伸線才匯聚叫虛像的哩。

【實】

522px-Lens1.svglarge_convex_lens

 

【虛】

522px-Lens1b.svgConcave_lens

 

所以『實點光源』、『虛點光源』不過『它』在哪裡的說法。物理現象『聚後實散』與『散前虛匯』,實際上是相同的吧。

因此一個一般光學矩陣

  \left( \begin{array}{cc} A &  B  \\ C & D  \end{array} \right)

,可以等效於一個透鏡

  \left( \begin{array}{cc} 1 & 0  \\ -\frac{1}{f_{eff}} & 1  \end{array} \right)

,在主平面參考系裡,享有著同樣的成像公式

\frac{1}{d_o} + \frac{1}{d_i} = \frac{1}{f_eff}}

又說什麼呢?設若以 {f_{eff}}^+ 表示物距 d_o 比等效焦距大,但是很接近那個焦距。{f_{eff}}^- 表達物距 d_o 比此等效焦距小,但是也很接近那個焦距。當此實、虛之際,聚、散之時

\frac{1}{d_o_{\to {f_{eff}}^+}} + \frac{1}{d_i_{\to + \infty}} = \frac{1}{f_{eff}}

\frac{1}{d_o_{\to {f_{eff}}^-}} + \frac{1}{d_i_{\to - \infty}} = \frac{1}{f_{eff}}

到底該哪樣解釋

\frac{1}{d_o_{\to f_{eff}}} + \frac{1}{d_i_{\to \pm \infty}} = \frac{1}{f_{eff}} 的啊??倘以現象而言,同也。皆平行光罷了!!

實發光體 d_o 自無窮遠處 + \infty 向凸透鏡之前焦距趨近,其像距 d_i 將由後焦距往後遠離,當 d_o \to {f_{eff}}^+ ,像將在無窮遠也 d_i \to \infty ,豈非透鏡後之平行光耶?★要是它從凸透鏡之主平面向後開始靠近前焦距面 d_o \to {f_{eff}}^- ,那麼 d_i \to -\infty ,難到能不是以『所見』為重,省略其透鏡後已然平行的乎!☆

試請讀者想想凹透鏡一致的乎★探探物貼 d_o \to 0 凹凸鏡面上之理耶☆

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