【正文】 elate to image quality can also be controlled by the lens design program. Specific construction parameters, such as radii, thicknesses, spaces, and the like, as well as focal length, working distance, magnification, numerical aperture, required clear apertures, etc., can be controlled. Some programs include such items in the merit function along with the image defects. There are two drawbacks which somewhat offset the neat simplicity of this approach. One is that if the firstorder characteristics which are targeted are not initially close to the target values, the program may correct the image aberrations without controlling these firstorder characteristic。 另一個經(jīng)常遇到的問題是一個設(shè)計會持續(xù)陷入到一個明顯的不良形式（當你知道有一個更好的，非常不同的，你想要的一個）設(shè)計中。 事實上，自動設(shè)計程序是極其有限的。 圖 表示面形的一個兩變量評價函數(shù)，有三個主要極小值（ A， B， C）和三個相對較不重要的極小值（ D， E， F）。 人們可以想象只有兩個變量參數(shù)的情況。對評價函數(shù)產(chǎn)生變化的每一項進行計算。 通常情況下 ,評價函數(shù)用一個單純的數(shù)值來表示系統(tǒng)的質(zhì)量，這個數(shù)值是通過評價函數(shù)的缺陷項經(jīng)過加權(quán)求和計算出來的。一些程序包括了隨圖像失真而變化的評價函數(shù)的項目。這種類型的評價函數(shù)的效率較為低下，因為它需要追跡大量的光線，但它所具有的 優(yōu)點也正是在于它追蹤了大量的光線，因此從某種意義上說它所包含的數(shù)據(jù)量很大，對于光線的反映十分的完整全面。使用缺陷的平方來計算可以確保一個負值的缺陷不會抵消其它的正值的缺陷。 畢業(yè)設(shè)計 (論文 )外文資料翻譯 系： 電子工程與光電技術(shù)系 專 業(yè)： 光電信息 科學與 工程 姓 名： 學 號： 外文出處： Smith W J. Modern lens design[M]. New York: McGrawHill, 2022. 附 件： ； 。典型的評價函數(shù)是許多圖像缺陷值的平方之和，通常這些圖像的缺陷通過視場中的三個位置參數(shù)來進行評價（除非該系統(tǒng)包括一個非常大或非常小的視場角）。因此，評價函數(shù)是光斑在幾個視場角的有效尺寸總和的均方根（ RMS）。具體的結(jié)構(gòu)參數(shù)如：半徑，厚度，空氣間隔以及焦距，工作距離，倍率，數(shù)值孔徑，光闌等，都是可以被控制的。用這些代數(shù)求解的半徑或空間來得到所需的射線斜率或高度。 優(yōu)化 鏡頭設(shè)計程序通常這樣操作 ： 每個變量參數(shù)變化 (每次一個 )的增量大小是選擇一個較大的值 (以獲得良好的數(shù)值精度 )和一個較小的值 (獲得本地微分 )之間的值。 如果優(yōu)化結(jié)果的變化很小 ， 非線性計算不會破壞過程以及結(jié)果 ， 盡管是一個 近似的結(jié)果 ， 但程序?qū)τ谠O(shè)計上的優(yōu)化計算將開始不斷重復，直到最終使設(shè)計達到最近似的局部最優(yōu)解。若換做 Y 點開始優(yōu)化，最低的極值將變?yōu)?C。為了在尋找最小值的過程中可以從這些極小值中“震蕩”逸出，設(shè)計如下所述。幸運的是 ， 這些條件都很少恰好滿足 ,并且他們可以很容易地被避免發(fā)生。 usually most are related to the quality of the image. However, any characteristic which can be calculated may be assigned a target value and its departure from that target regarded as a defect. Some less elaborate programs utilize the thirdorder (Seidel) aberrations。 after the system is jolted, it is probably in a highly nonlinear region and a big damping factor may be needed to prevent a breakdown. A manual increase of the damping factor can often avoid this problem. Another oftenencountered problem is a design which persists in moving to an obviously undesirable form (when you know that there is a much better, very different one— the one that you want). Freezing the form of one part of the lens for a few cycles of optimization will often allow the rest of the lens to settle into the neighborhood of the desired optimum. For example, if one were to try to convert a Cooke triplet into a split front crown form, the process might produce either a form which is like the original triplet with a narrow air spaced crack in the front crown, or a form with rather wild meniscus elements. A technique which will usually avoid these unfortunate local optima in this case is to freeze the front element to a planoconvex form by fixing the second surface to a plane for a few cycles of optimization. Again, one must know which lens forms are the good ones.