Recording of efficient high-order Bragg reflectors in opticalfibres by mask image projection and single pulse exposure with anexcimer laser

A technique using high resolution mask projection for creating efficient Bragg grating reflectors in optical fibres by single excimer laser pulse exposure is described. Using a deep UV projection system with a large image field size and micrometre resolution, gratings with periods between 1 and 6 μm have been recorded in Ge-doped fused silica fibres that produce high order Bragg reflections in the wavelength range 1.43-1.65 μm     

激光光刻大面积扫描投影成像光学系统测试及评价

基于351nm XeF激光大面积投影成像光刻系统,通过对其光学系统包括光学照明系统和折叠投影系统进行光学性能测试。由激光经过柱面透镜、微透镜阵列均束器以及投影折叠物镜之后产生的能量及光束质量变化,将准分子激光光束均匀性评价指标部分运用到光学系统的评价之中,得到光学系统在不同关键位置的能量分布曲线以及平顶因子关系图,表明微透镜阵列均束器虽保证了整个光学系统各处光斑的均匀性,但衍射却造成了能量利用率的降低。同时,通过对印制电路板(PCB)和玻璃(ITO)进行曝光和显影实验,表明该双远心共焦投影光学系统,只要控制使均匀输出的能量符合曝光剂量,就能够满足分辨率的要求。     

智能激光3D投影空间定位精度分析

为了解决激光3D投影定位无法兼顾高精度、实时性、智能补偿定位的问题,搭建了一种基于激光跟踪定位技术的智能激光3D投影系统,并进行空间精度分析。首先,建立激光3D投影系统数学模型;其次对激光3D投影系统进行光学中心标定,再利用投影承接部件基准点对部件坐标系进行标定,从而完成智能激光3D投影系统的标定及搭建;最后,建立智能激光3D投影定位精度模型。仿真结果显示,激光3D投影仪投影区域中间部分精度最佳,由激光跟踪测量精度引起的投影承接面投影点误差小于投影仪引起的投影承接面投影点误差。实验结果显示:在3~4 m的投影距离上,所研制的智能激光3D投影系统的投影形状及位置准确度可以优于0.3 mm。与传统的激光投影系统相比,该系统解决了大尺寸投影承接部件不能大量安装合作目标问题,使工作中无需目标反射头及校准工装,省略校准过程,当投影系统或被测部件移动或漂移时,智能化识别、解算、补偿相对位移量,保证实时、精确投影至正确位置,极大提高了投影定位系统的工作精度和定位效率。     

用于平板显示LTPS制备的ELA光束整形系统

介绍了多晶硅薄膜较非晶硅薄膜在平板显示领域的优势以及准分子激光晶化制备多晶硅膜的结晶过程。介绍了透镜阵列实现匀光的原理。阐述了典型的准分子激光退火线型光束整形系统的扩束、匀光、投影等结构。并介绍了连续横向固化技术在准分子激光制备低温多晶硅领域的应用。讨论了准分子激光退火光学系统的发展现状,指出了其在平板显示行业的重要意义。     

激光投影虚拟键盘的研究与设计

针对激光投影虚拟键盘的实际需求,结合嵌入式技术和图像处理技术,研究设计了一套激光投影虚拟键盘设备.硬件模块以ARM Cortex-M4架构的微处理器作为主控器,采用数字型CMOS摄像头;软件模块的处理过程中利用MATLAB进行部分数字图像的处理并将处理结果导入到微控制器中进行嵌入式图像处理.在完成系统的软硬件设计后,对整个系统的功能进行测试,由测试结果表明整个系统达到了预期的目的.     

印刷电路板激光投影成像照明系统均匀性分析

针对351 nm波长的XeF准分子激光器,自行设计了用于高精度、高产率、大面积且常规抗蚀剂曝光的印刷电路板(PCB)激光投影成像照明系统.根据准分子激光的部分相干平顶高斯光束(PCFGB)理论模型,对微透镜阵列器(MLA)均束的衍射特性进行了理论分析.由PCFGB分布函数、稳定光强输出的衍射角和菲涅耳-基尔霍夫衍射积分公式,定量分析衍射效应对MLA均束的影响.理论计算表明,微透镜边缘发生菲涅耳衍射和微透镜产生的多光束干涉都能引起光振幅调制,只不过衍射产生的尖峰更明显地出现在光束边缘.同时,由数值积分得到的PCFGB曲线,发现9×9 MLA均束器既能保证多个微透镜产生光束叠加的均匀性,又最大程度地减少了衍射和多光束干涉效应.通过采取加正六边形光阑的方法,不仅能满足大面积无缝扫描光刻的需要,而且能剪裁由衍射引起的光束边缘尖峰.由ZEMAX光学设计软件模拟其效果,显示其加工窗不大于±2%.     

Linewidth control in projection lithography using a multilayer resist process

Linewidth control using a tri-layer resist system on wafers with topography is investigated. An absorbing dye is incorporated in the bottom layer to improve the usable resolution. Resist patterns of 1-µm lines and spaces over aluminized topography are demonstrated using a projection aligner. The advantages of a multilayer system are investigated using an exposure and development simulation program for optical lithography. The relative contributions of planarization and reflection suppression are discussed.     

激光投影显示中新型散射体的散斑抑制

激光的强相干性造成了激光投影显示中出现大量干涉条纹和散斑,为了消除干涉条纹和散斑对图像质量的影响,采用旋转新型散射体(Engineered DiffuserTM)的方法在一定积分时间内获得叠加的清晰图像。首先,介绍了激光投影显示中散斑的成因及采用时间平均抑制散斑的理论依据。接着,分析了传统散射体毛玻璃和Engineered DiffuserTM在结构及功能上的区别。最后,建立了旋转新型散射体抑制散斑的激光投影显示实验装置,对比验证了旋转新型散射体抑制散斑的效果。实验结果表明:散斑对比度降低到3.08%,图像质量良好,无明显干涉条纹。该方法满足商用激光投影显示体积小、简单易行等要求。     

Excimer Laser Projection Photoablation Patterning of Metal Thin Films for Fabrication of Microelectronic Devices and Displays

A nonlithographic process is demonstrated for patterning Al, Cr, Cu, Ni, Ti, and W thin films, which are widely used in microelectronic and display fabrication. A projection photoablation process using 248-nm-deep ultraviolet radiation from a KrF excimer laser was used to pattern a polyimide film coated on a SiN layer deposited on glass. The photoablation-patterned polyimide film was used as a sacrificial layer in a lift-off patterning process for the metal films, which resulted in clean metal patterns with fine line-edge definition being fabricated after lift-off. This process provides a simpler and more economical patterning technique compared to conventional lithography methods, eliminating the developing and etching steps.     

Phase unwrapping based on deep learning in light field fringe projection 3D measurement

Phase unwrapping is one of the key roles in fringe projection three-dimensional (3D) measurement technology. We propose a new method to achieve phase unwrapping in camera array light filed fringe projection 3D measurement based on deep learning. A multi-stream convolutional neural network (CNN) is proposed to learn the mapping relationship between camera array light filed wrapped phases and fringe orders of the expected central view, and is used to predict the fringe order to achieve the phase unwrapping. Experiments are performed on the light field fringe projection data generated by the simulated camera array fringe projection measurement system in Blender and by the experimental 3×3 camera array light field fringe projection system. The performance of the proposed network with light field wrapped phases using multiple directions as network input data is studied, and the advantages of phase unwrapping based on deep learning in light filed fringe projection are demonstrated.     

Removal of hot spot speckle on rear projection screen using the rotating screen system

This paper investigates a method to remove hot spot speckle, which is produced by laser-long coherence, on a projection screen. The objective of the work has been to first create an image from a digital light processing (DLP) display system using an RGB laser source. We then successfully obtained a high-quality image with speckle contrast, which is less than 2% when the screen was rotated by piezoelectric motor.     

A portable image overlay projection device for computer-aided open liver surgery

Image overlay projection is a form of augmented reality that allows surgeons to view underlying anatomical structures directly on the patient surface. It improves intuitiveness of computer-aided surgery by removing the need for sight diversion between the patient and a display screen and has been reported to assist in 3-D understanding of anatomical structures and the identification of target and critical structures. Challenges in the development of image overlay technologies for surgery remain in the projection setup. Calibration, patient registration, view direction, and projection obstruction remain unsolved limitations to image overlay techniques. In this paper, we propose a novel, portable, and handheld-navigated image overlay device based on miniature laser projection technology that allows images of 3-D patient-specific models to be projected directly onto the organ surface intraoperatively without the need for intrusive hardware around the surgical site. The device can be integrated into a navigation system, thereby exploiting existing patient registration and model generation solutions. The position of the device is tracked by the navigation system's position sensor and used to project geometrically correct images from any position within the workspace of the navigation system. The projector was calibrated using modified camera calibration techniques and images for projection are rendered using a virtual camera defined by the projectors extrinsic parameters. Verification of the device's projection accuracy concluded a mean projection error of 1.3 mm. Visibility testing of the projection performed on pig liver tissue found the device suitable for the display of anatomical structures on the organ surface. The feasibility of use within the surgical workflow was assessed during open liver surgery. We show that the device could be quickly and unobtrusively deployed within the sterile environment.     

提高准分子激光打孔质量的方法研究

为了提高准分子激光打孔质量,分析了影响现行加工系统打孔质量的因素,在此基础上提出利用钻孔法改进打孔效果的解决方案。根据此方案设计了加工光路,进行了微孔加工实验。实验结果表明,采用248nm准分子激光加工有机材料聚甲基丙烯酸甲酯,微孔形状规则,孔径锥度可减小至0.055。该加工系统和方法提高了微孔加工的速度和质量,在微加工领域具有很好的实际应用价值。     

基于视景仿真技术的虚拟激光投影动态交互方法北大核心CSCD

虚拟激光投影在动态交互时,易用性差、鲁棒性低都会导致交互方法的交互性能变差,为提高激光投影交互效果,提出基于视景仿真技术的虚拟激光投影动态交互方法。利用VEW方法采集激光投影视频图像,利用加权平均法对采集到的视频图像背景去噪,并基于红绿蓝三原色建立视频的RGB彩色空间模型,对背景去噪后的图像灰度转换后,进行阈值分割;依据预处理结果确定激光投影中心点位置,通过投影的中心点映射,实现投影动态交互;使用视景仿真技术对交互场景图像的交互效果实施增强,提高激光投影的动态交互性能。实验结果表明,运用该方法开展激光投影动态交互时,交互性高、易用性好、鲁棒性高。     

激光投影显示色彩管理系统

本文提出了一种适用于激光电视的新的颜色显示管理方法,该方法建立了激光三基色颜色显示与荧光粉三基色颜色显示之间的色度转换关系,不仅扩大了色彩显示的色域,而且实现两种色彩管理系统的相互兼容,该方法对于LED显示等宽色域显示系统的颜色管理,也有积极的借鉴意义。     

用光致抗蚀剂膜层制作衰减相移掩模

提出一种用光致抗蚀剂膜层制作单层结构衰减相移掩模的新方法,介绍这种方法的原理和制作工艺,并给出这种方法制作的衰减相称掩模用于准分子激光光刻实验,得到显著提高光刻分辨力的实验结果。     

Unsupervised hyperspectral image analysis with projection pursuit

Principal components analysis (PCA) is effective at compressing information in multivariate data sets by computing orthogonal projections that maximize the amount of data variance. Unfortunately, information content in hyperspectral images does not always coincide with such projections. The authors propose an application of projection pursuit (PP), which seeks to find a set of projections that are "interesting," in the sense that they deviate from the Gaussian distribution assumption. Once these projections are obtained, they can be used for image compression, segmentation, or enhancement for visual analysis. To find these projections, a two-step iterative process is followed where they first search for a projection that maximizes a projection index based on the information divergence of the projection's estimated probability distribution from the Gaussian distribution and then reduce the rank by projecting the data onto the subspace orthogonal to the previous projections. To calculate each projection, they use a simplified approach to maximizing the projection index, which does not require an optimization algorithm. It searches for a solution by obtaining a set of candidate projections from the data and choosing the one with the highest projection index. The effectiveness of this method is demonstrated through simulated examples as well as data from the hyperspectral digital imagery collection experiment (HYDICE) and the spatially enhanced broadband array spectrograph system (SEBASS).     

PLZT ceramic display devices for slow-scan graphic projection displays

A projection display device for slow-scan graphics has been developed using the scattering properties of PLZT ferroelectric ceramics. The device consists of a ferroelectric-photoconductor sandwich in which a Cd1-xZnxS mixture is used as a photoconductive film. The composition of the film is controlled to provide peak photosensitive response at 441.6 nm, corresponding to the blue line from a He-Cd laser. Any image can be written into the device with a combination of steered laser beam (less than 1 mW) and electrically applied pulses, held for an indefinite time without sustaining power and erased electrically. Because of the properties of the photoconductive film, selective erase and simultaneous reading and writing are possible. The all-solid-state structure of the device combined with the scattering properties of the ceramic permit the device to be used as a slide in a conventional 35-mm projector.     

二元光学元件的制作及其误差分析

详细介绍了二元光学元件制作的光刻技术和一些新的制作工艺,包括薄膜沉积法、激光束或电子束直接写入法和准分子激光加工法．针对用于ＣＯ２激光器模式优化的二元光学反射镜,分析了元件制作误差,包括掩模对准误差、台阶刻蚀深度误差和台阶刻蚀宽度误差对谐振腔振荡模式的影响．     

Optimization of an injection-controlled excimer laser guided byanalytical modeling

The application of an analytical model describing the injection control of pulsed laser systems is successfully demonstrated for the design of a scaled XeF(C→A) excimer laser system. Enhancements to an earlier version o the model which improve the treatment of spatial beam overlap and saturation, unpumped volume, intracavity losses, and a noninteger number of roundtrips in the unstable resonator are described. These result in the accurate simulation of injection-controlled laser performance over a wide range of unstable resonator magnifications, mirror spacings, and intracavity optical losses. Excellent agreement between calculated and experimentally observed energies and temporal profiles of the injection-controlled laser output was obtained