在影像系統中容易由於焦距的不準確，對影像的品質造成影響。這篇論文目
的在設計與分析一種治療失焦的薄膜。
景深(depth of field)表示可以形成清楚成像的範圍。 由於透鏡只能夠將光
聚到某一固定的範圍(焦距)，越遠離此範圍則會越模糊。在1995 年由Dowski 和
Cathey 提出。可以利用波前編碼(Wave-front coding)[1]來增加系統的景深，使
影像不易受到焦距不準確而模糊。做法是靠著在透鏡前加上一治療薄膜，便可在
相同條件下延長景深的範圍。
本篇論文是以二階相位薄膜為基礎拓展到多階的相位薄膜，在模擬的結果中
顯示，多階的相位薄膜有不錯的表現。

The image quality will degrade if the misfocusing problem occurs in the imaging
system. This paper is aimed to design and analyze a phase mask for mutifocusing
problem.
Depth of field is the range to get a clear image. As the lens can only gather the light
in a fixed range. Image will be more blurred when it is more from this range. In 1995
Dowski and Cathey proposed the wave-front coding to increase the system's depth of
field so that the image will less susceptible to blur due to the mutifocusing problem. A
treatment with a mask before the lens can extend the depth of field.
In this paper, we extend to multi-levels phase mask. The simulation results show
that multi-level phase mask has a better performance than the two-level phase mask.

論文審定書……………………………………………………… i
誌謝………………………………………………………… ii
中文摘要………………………………………………….….. iii
英文摘要………………………………..……………………. iv
第一章引言…………………..……………...………………..1
第二章 光學影像系統之基礎……………………………….4
2.1 同調影像系統………………………………………. 4
2.2 非同調影像系統……………………………...……..… 5
2.3失焦概念………………………….…………...………….8
2.4多重焦距下的光學轉移函數…….…………...….… … 10

第三章 各種治療多重聚焦薄膜………………………………12
3.1 三次方薄膜……………………………………....….... 12
3.2 二階薄膜……………………………………….……..... 16
第四章 新的治療多重聚焦薄膜…………………….………17
4.1 環狀薄膜（遞迴型）………………………….…….... 17
4.2 環狀薄膜（非遞迴型）…………………….…….... 25

第五章 模擬結果與分析………………………….……..... 30
5.1 模擬結果和比較………………………….….….... 30

第六章 結論…………………………………..…….…….... 45
參考文獻……………………………...……….…… 46

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