【作者】 王金刚；

【导师】 袁小聪；

【作者基本信息】 南开大学 ， 光学工程， 2013， 博士

【摘要】 集成成像技术是由Lippmann在1908年提出,近十几年来得到迅速发展的新型三维显示技术。其基本原理是利用微透镜阵列记录物体三维场景,利用微透镜阵列再现三维场景。集成成像技术具有许多优点。与偏振、红绿等需要佩戴眼镜的立体显示技术相比,它是一种裸眼三维显示技术；与光栅、柱面透镜等三维显示技术相比,它可以显示三维视场信息；与全息三维显示相比,它不需要激光记录和再现。简而言之,集成成像是一种裸眼、非相干、全视角三维显示技术。然而,这种显示技术也并非十全十美。如分辨率受到显示器像素大小和微透镜数值孔径的制约。微透镜的数值孔径和显示器的像素大小限制了景深。因此,提高集成成像系统的景深和分辨率具有十分重要的意义。本文主要工作是利用波前编码技术拓展集成成像系统的景深,其中包括设计优化用于景深拓展的位相片和具体景深拓展实验。具体内容可以概括为以下6个方面：1、介绍了集成成像技术的原理。分析了集成成像的特征参数,包括视场角、分辨率和景深。重点研究了现有扩大景深的方法,进而提出了基于波前编码技术拓展集成成像系统景深的方法。2、分析了波前编码技术增大景深的原理。指出波前编码技术的本质在于利用位相片改造系统的光学传递函数,使其对离焦变化不敏感。分析了现有两种产生波前编码位相片的方法。给出了各种位相片的表达式。3、提出了一种产生高质量三次位相片的方法。通过在传统位相片上加上闪耀光栅,来克服传统位相片零级光的干扰,提高了位相片衍射图样的质量。以三次位相片为例,通过在三次位相片上加上闪耀光栅,形成闪耀型三次位相片。实验结果表明,闪耀型三次位相片的光斑分布要远好于传统三次位相片的光斑分布。4、提出了一种利用波前编码技术拓展相机阵列集成成像系统景深的方法。具体实验过程中,利用了三次位相片和CCD相机组成波前编码相机。并用单个波前编码相机在二维电动平移台的移动来代替波前编码相机阵列。获取的元素图像结果表明,波前编码相机整列成像系统获取的元素图像景深有着明显增加。同时,我们利用投影仪和微透镜阵列系统组成集成成像显示系统。重构实验显示,波前编码系统的景深得到明显提高。5、提出将波前编码技术运用到显微集成成像系统中。搭建了波前编码显微系统。通过对头发和手表中的齿轮进行成像,获取了编码的元素图像阵列。利用维纳滤波对编码图像进行了解码。结果表明,与传统的显微集成成像相比,解码图像景深有所提高。6、设计并制作了一种改进型正弦位相片。与正弦位相片相比,这种位相片多了一个可以优化的参数。采用一系列的评价函数对现有的各种位相片(包括正弦型、三次型和改进对数型)进行评价。评价结果表明,改进型正弦位相片比三次型、正弦型和改进对数型位相片有更高的景深增强本领。同时,在光刻胶上制作了改进型位相片,并进行了成像实验。实验结果表明,改进型正弦位相片具有景深拓展能力。更多还原

【Abstract】 Integral imaging, as a novel3D imaging and display technique, first proposed by Lippmann in1908, has been resurrected and developed rapidly during these ten years. The principles of this technique can be divided into two parts:Recording3D scene and reconstruct3D scene. To record3D scene, the information of3D scene is recorded onto2D sensor by a micro lens array (MLA). To reconstruct3D scene, we just reverse the record process. There are lots of advantages of integral imaging technique. Compared with polarization and red-green3D display techniques, no glasses are required by integral imaging. Compared with grating and cylindrical lens array3D display technique, full parallax and quasi-continuous views angles can be display by integral imaging. Compared with holography3D display technique, no laser is needed during recording and reconstructing process by integral imaging. All in all, integral imaging is a novel3D technique with merits of viewed by naked eyes, no need of coherent light and displayed with full parallax views. However, every coins has two sides, integral imaging is not perfect. Two major drawbacks of this technique are poor lateral resolution and limited depth of field (DOF), which is either constrained by pixel of display, or limited by sizes of MLA, or both of them. Therefore, it is quite meaningful to improve the DOF and resolution of integral imaging.To contribute to this promising3D technique, we have put our effort into improving the DOF of integral imaging system during" last three years. This dissertation mainly focus on improve DOF of integral imaging system by wave coding technique. Designing new phase plate and concrete experiment are also included. The dissertation can be divided into the following six parts:Firstly, the principles of integral imaging are introduced and three main parameters (view angle, resolution and DOF) of integral imaging are analyzed. After most existent methods to extend DOF of integral imaging system are reviewed, we proposed a new method, which is using wavefront technique to enlarge DOF of integral imaging system. Secondly, we introduce the principles of wavefront coding technique and discuss several asymmetric phase plate used in wavefront coding system. Later, we reviewed all kinds of phase plate to extend DOF. And several continuous relief phase plates are fabricated by laser direct writer.Thirdly, a new method of generating high quality phase plate is proposed. By adding a conventional blazed grating onto a cubic phase plate, it enables elimination of direct incident illumination in the reconstructed beam. Experimentally measured intensity distribution of the blazed cubic plate is found in much better than traditional cubic phase plate.Fourthly, we demonstrate an experimental approach to enhancing DOF of the integral imaging system by using a coded camera array with a cubic phase plate (CPP). A7x7coded elemental image array is acquired by moving a single CPP coded camera placed on the electric translation stage for7x7times. The coded elemental images captured by the coded camera array have larger DOF than common camera array. After digital process of the coded elemental images, we obtained elemental images with enhanced DOF for3D display.Fifthly, we try to apply wavefront coding technique to integral imaging microscopy. We build the wavefront coding integral imaging system and choose hair of a man as a3D sample. After digital process of the coded elemental images, we obtained elemental images with a little enhanced DOF.Finally, an improved sinusoidal phase plate is proposed by adding a new parameter to a conventional sinusoidal phase plate. A series of performance comparisons are made among various phase plates including sinusoidal, cubic phase and the modified logarithmic phase. The results demonstrate that the improved sinusoidal phase plate can further extend the depth of field in incoherent hybrid imaging systems, with a lower surface relief phase structures fabricated in photoresist (AR-N4340, ALL Resist, Germany).更多还原