Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/91325
標題: Design and fabrication of diffraction optical elements for stereoscopic measuring system
立體量測系統之繞射光學元件設計與製作
作者: 杜佩芩
Pei-Qin Du
關鍵字: computer generated hologram
IFTA
speckle diffractive element
two-leveled quantification
電腦全像片
傅立葉迭代法
斑點繞射元件
二階化
引用: [1] Horn, B.K.P., 'Obtaining Shape from Shading Information,' chapter 4 in The Psychology of Computer Vision, Winston, P. H. (Ed.), McGraw-Hill, New York, April 1975, pp. 115-155 [2] Joseph W. Goodman,'Introduction to Fourier Optics',McGraw-Hill,Inc. 1996 [3] D. Gabor. 'A new microscopic principle', Nature, 161, pp. 777-778, May 1948 [4] B. R. Brown, A. W. Lohmann. 'Complex spatial filtering with binary masks', Applied Optics, 5, 6, pp. 967-969, June 1966. [5] Bernard C. Kress, Patrick Meyrueis,' Applied Digital Optics: From Micro-Optics to Nanophotonics',26 OCT 2009 [6] L. B. Lesem, P. M. Hirsch, J. . Jordan, Jr. 'The Kinoform: A New Wavefront Reconstruction Device', IBM Journal of Research and Development, 13, 2, pp.150-155, 1969. [7] Victor Soifer, Leonid Doskolovich, 'Iterative Methods for Diffractive Optical Elements Computation' [8] 林政宏,'相位式電腦全像片之研究',國立台灣師範大學光電科技研究所,碩士論文,中華民國93年 [9] Frank Wyrowski and Olof Bryngdahl, 'Iterative Fourier-transform algorithm applied to computer holography', J. Opt. Soc. Am. A/Vol. 5, No. 7/July 1988 [10] Kazuhiro Suzukia and Yuji Sakamotoa, 'Measurement method for objective evaluation of reconstructed image quality in CGH.' Proc. of SPIE Vol. 8644 864412-7(2013) [11] 林嘉軒,'以遞迴傅立葉法設計非均勻相位繞射光學元件之研究',國立台北科技大學,光電技術研究所,中華民國92年 [12] 張耿維,' 純相位繞射光學元件的設計並以液晶空間光調製器實現之',國立中央大學光電科技研究所,碩士論文,中華民國94年 [13] 江昶慶,'以電腦全像片實現之遠場繞射投影顯示技術',國立交通大學顯示科技研究所,碩士論文,中華民國100年 [14] Ignacio Moreno et al.,'effects of amplitude and phase mismatching errors in the generation of a kinoform for pattern recognition', Jpn. J. Appl. Phys.Vol. 34 (1995) pp. 6423-6432 [15]龍俊霖,'以全像光學元件與空間頻率為基礎隻立體量測系統',國立中興大學機械工程所,碩士論文,中華民國102年 [16]黃韋閔,' 應用於Kinect立體感測器之新式投影元件設計',國立中興大學機械工程所,碩士論文,中華民國101年
摘要: The Kinect is a stereoscopic sensor which can sense the depth and position information of objects. Its recording method is called the light coding. The principle is to project a light pattern with speckles into the space and generate different speckle distribution at each position in the space. That is to mark each position in the space. Generally, the Kinect stereoscopic sensor was used to capture body's actions in game applications. Because the human body is of big range area, it doesn't need high dense speckle patterns to capture body's actions. However, if we want to apply the light coding technology to the high-precision measuring systems, it is necessary to increase the density of speckle so that the profile of objects can be measured more precisely. The purpose of this study is to design the phase-only binary diffractive optical element (DOE) which can generate speckle patterns with higher density. The algorithm for achieving this element is the same as that for designing a computer generated hologram (CGH). It adopts the Fourier transform and inverse Fourier transform to iteratively calculate the wavefront distribution between input plane (element plane) and output plane (diffractive plane) and sets different constrains in each plane. In the input plane, the amplitude of input wavefront amplitude was set to be 1 and the phase was binarized. In the output plane, the wavefront amplitude was changed into the goal pattern values. The phase among the whole calculating process was not changed. After several iterations, the diffractive pattern generated by the element after being calculated using the algorithm would be close to the goal pattern. It is called the iterative Fourier transform algorithm (IFTA). During the IFTA process, the goal pattern was made by Excel software to produce finer speckle distribution. The spot size of a speckle was 4?4 pixels. There are goal patterns of 400?400, 210?210, 1000?1000 pixel matrices designed with speckle spacing of 2, 3, and 5 pixels, respectively. The designed speckle patterns occupied only half area of the overall goal patterns. The reason is that the two-leveled quantified element would generate a conjugate image in the diffractive pattern. Both diffractive images finally constitute the whole speckle distribution. The designed goal patterns were substituted into the IFTA to count the phase mapping of the speckle elements. These calculated phase mappings were then sent into the spatial light modulation (SLM) for observing whether the diffractive patterns would compliance with the design or not. The designed CGHs were vectorized by the WinTopo software, modified by the AutoCAD software, and drawn into the photo masks. Finally, the speckle elements were fabricated by the technologies of photolithography and etching processes for verifying the properties. The original speckle element of the Kinect stereoscopic sensor can produce a diffractive light field with the dimension of about 68?54cm at the distance of 240cm from the element. The spacings between spots are from 0.6cm to 3cm. The elements designed in this study can generate the regular speckle pattern with the spot spacing of 0.7cm at the same distance. The result shows that the way to design the speckle element can indeed improve the spot density.
Kinect為一個可感測物體深度與位置資訊的立體感測器,其記錄深度資訊的技術稱為光空間編碼技術。原理為投射一個散斑光場到空間中,造成空間中不同位置的散斑分佈皆不相同,也就是說將空間上每個位置作記號。一般而言,此感測器被使用在遊戲應用中對人物動作捕捉。由於人體是屬於大範圍的面積,所以其散斑密度並不需要很高即可捕捉到人體的動作與位置,然而若想讓光空間編碼技術應用在更高精度的量測系統上,勢必要提高散斑的密度才能更精確的量測物體。 本研究目的為設計出能繞射出密度較高之斑點圖形的二階式純相位繞射光學元件(diffractive optical element, DOE),此元件的演算方法與電腦全像片(computer generated hologram, CGH)的設計方式相同,其方法是在輸出面(繞射面)與輸入面(元件面)之間以傅立葉及反傅立葉來回計算波前分佈,並且分別在輸入面與輸出面上做不同的條件設定。在輸入面中設定輸入光場振幅為1、將相位作二階化,而輸出光場振幅改為目標圖形值,其中相位則是保留不作任何更動。經由多次迭代後,經此演算法計算出之元件面所繞射出的光場會愈趨近於目標圖形。此方法即稱為傅立葉迭代演算法(Iterative Fourier transform algorithm, IFTA)。 在IFTA過程中,輸出的目標圖形是以Excel軟體設計精細度較高的斑點分佈,設計出斑點大小為4?4畫素,間距分別為2、3、5等畫素的單位斑點矩陣整合成整體畫素為400?400、210?210、1000?1000之目標圖形。在整個目標圖形斑點只占據整體面積的一半,由於二階化後元件所重建的繞射圖形會產生共軛影像,兩繞射影像進而組成整體之斑點分佈。將目標圖形(斑點圖形)代入傅立葉迭代演算法來計算散斑元件的相位圖形。之後,將設計出來的相位圖形輸入光空間調製器(spatial light modulation, SLM)中,觀測其繞射圖案是否與設計吻合。所設計的電腦全像片(散斑元件)以Wintopo軟體進行向量化,並輸入AutoCAD軟體中修改並繪製成光罩。 最後,以微影與蝕刻技術製作散斑元件,並進行元件之性質驗證。原Kinect 感測器中的散斑元件於在距離元件240cm處能夠產生一個大小約為68?54cm的繞射光場,繞射的光斑間距從0.6~3cm,而本研究所製的散斑元件可以在相同距離處繞射出斑點間距為0.7cm的規律斑點圖。證明了本研究的設計方式確實可以提高斑點的密度。
URI: http://hdl.handle.net/11455/91325
文章公開時間: 2016-08-31
Appears in Collections:機械工程學系所

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