中文摘要
近年來廣泛使用的數位相機等取像裝置，在消費性電子產品市場中已經引起許多的重視。然而，與傳統的照相機相比，量測和提升數位相機的影像品質是很重要的；例如，數位取像光學模組的微小化所造成的繞射效應很容易地降低影像的解析度。調變轉移函數(modulation transfer function, MTF)已廣泛被使用來評估透鏡成像品質優劣的重要指標。因此，這篇論文的主要目的是以不同的擴散函數方法，進行MTF量測系統發展之優缺點分析。
在本論文中首先探討點、線、與邊緣擴散函數方法的學理以及其對應量測組態。這些組態所使用的準直光源，是利用準直透鏡與各別的圖樣（針孔、狹縫與刀邊）來產生。再分別利用這些準直光源來測試待測模組的成像品質，並使用影像感測器擷取相關資訊，根據個別的演算法，在電腦計算出待測成像模組的MTF值。針對這些組態的量測方法，我們經由學理分析與實驗來分別比較這些量測組的優劣點。

關鍵字：調變轉移函數、點擴散函數、線擴散函數、邊緣擴散函數

ABSTRACT
For many years, the widening use of digital imaging products, e.g., digital cameras, has given rise to much attention in the market of consumer electronics. However, it is important to measure and enhance the imaging performance of the digital ones, compared to that of conventional cameras. For example, the effect of diffraction arising from the miniaturization of the optical modules tends to decrease the resolution of the image. As a figure of merit, modulation transfer function (MTF) has been broadly employed to estimate the image quality. Therefore, the objective of this paper is to compare the advantage and disadvantages of the MTF measurement systems using different spread function methods.
In this paper, a theoretical framework is first briefly presented and then, a cost-effective approach is proposed. In this approach, we use pinhole, slit, knife-edge and collimating lens to produce the point, line and edge collimation light sources. Collimated light going through the lens module under test is consecutively detected by the imaging sensor of the proposed system. The images formed by the optical modules are acquired by a computer and then, they are processed by algorithms for computing the MTF. Finally, the advantages and disadvantages of the MTF measurement systems using different spread function methods are presented in this thesis.

Key words: modulation transfer function, point-spread function, line-spread function, edge-spread function

[1] Glenn D. Boreman, Modulation Transfer Function in Optical and Electro-optical systems, 2th ed., SPIE, Washington, pp. 69–107, 2001.
[2] J. W. Goodman, Introduction to Fourier Optics, 2nd ed., McGraw-Hill, New York, pp. 137–154, 1996.
[3] R. R. Shannon, The Art and Science of Optical Design, Cambridge U. Press, Cambridge, UK, pp. 265–333, 1997.
[4] C. S. Williams and O. A. Becklund, Introduction to the Optical Transfer Function, Wiley, New York, pp. 149–158, 1989.
[5] http://www.trioptics.com/
[6] http://www.oeg-messtechnik.de/
[7] http://www.optikos.com/
[8] H. Fujita et al, “A simple method for determining the modulation transfer function in digital radiography, ” IEEE. Med. Img., vol. 11, no.1, 1992
[9] E. Samei et al, “Comparison of edge analysis techniques for determination of the MTF of digital radiographic systems, “ IOP., 2005
[10] W. Hon-Sum, “Effect of knife-edge skew on MTF measurements of CCD imagers employing a knife-edge,” Opt. Eng., 30, pp. 1394–1398, 1991.
[11] H. J. Pahk *, Suk Won Lee, Dong Sung Lee, “Computer aided measurement and compensation system for focal length of lenses in camera manufacture based on the MTF performance using the line CCD sensor” International Journal of Machine Tools & Manufacture 40, pp.1493–1511, 2001.
[12] A. Daniels, G. D. Boreman, A. D. Ducharme, and E. Sapir, “Random transparency targets for modulation transfer function measurement in the visible and infrared region,” Opt. Eng., 34, pp. 860-868, 1995.
[13] Sampo M. Backman and Anssi J. Makynen, “Random target method for fast MTF inspection,” JOSA, 2004
[14] E. Levy, D. Peles, M. O. Lipson, and S. G. Lipson, “Modulation transfer function of a lens measured with a random target method,” Appl. Opt., 38, pp. 679-683, 1999.
[15] J. C. GRISOLIA, “A Device for the optical transfer function measurement,” J. Optics (Paris), 1985, vol. 16, no 2, pp. 77-81.