應用微機電可形變鏡片與自由曲面組成微型自動對焦相機系統

Compact Autofocus Camera with MEMS Deformable Mirror and Freeform Surface

張瑋玲(Wei-Ling Chang)

指導教授 ： 蘇國棟

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.10325

摘要

我們實驗室提出一個微小型並能夠自動對焦的相機模組,不同於傳統相機的對焦方式為移動元件來達到不同的焦距,我們的相機模組採用的是我們實驗室製造的微機電可形變鏡面(MEMS deformable mirror),當物體在無窮遠處時, deformable mirror為平面;當物體移近時, deformable mirror彎曲,便可成像在相同位置的影像感測元件如CCD、CMOS上。一開始這個相機模組是200萬畫素,而藉由多加一面球面透鏡當孔徑光欄以及精確調整鏡組中每一參數的數值,可以大幅改善像差,增加成像品質。而這個設計可以再進階,我們藉由設計,從200萬畫素擴充到800萬畫素,而在思考了成本考量之後,我們決定將透鏡數量由三面減少至兩面,並將反射鏡指定為由Zernike 方程式所描述的自由曲面來修正像差, deformable mirror也設計成自由曲面,此時,一個800萬畫素有自動對焦功能且視野可達±26°的相機模組便可完成,這個系統的MTF值在空間頻率為113.5/mm處可以高於30%。

關鍵字

微機電可形變鏡片 ； 自動對焦 ； 調變轉換函數 ； 自由曲面

並列摘要

Our lab proposed a miniature autofocus camera without moving parts. We substantiated the autofocus camera by utilizing a MEMS deformable mirror(DM) made by our lab. When the objects are in the infinity, the DM is flat; When the objects get closer, the DM actuates. At first, our camera can cover 2-Mega-Pixel image with pixel size 2.2μm × 2.2μm. We added one more lens as a stop and specified the beginning parameters in the camera to correct the aberration and increase the image performance. This design can be further improved. We expanded 2-Mega-Pixel image plane to 8-Mega-Pixel image plane with pixel size 1.4μm × 1.4μm. For the concern of the cost, we distributed the optical power of the adding lens to the fixed mirror and the deformable mirror, and we designed them as freeform surfaces to compensate aberrations. We described the fixed mirror by Zernike polynomials. Finally, a 8M pixel auto-focus image system whose FOV is ±26° can be achieved. The MTF at 113.5 spatial frequency is above 30%.

並列關鍵字

MEMS deformable mirror(DM) ； auto-focus ； MTF ； freeform

參考文獻

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