紫外成像器件中衍射微透镜阵列设计与研制

为了提高紫外成像器件的填充因子,解决凝视型高性能紫外成像器件的核心技术问题,根据标量衍射理论设计了用于128×128日盲型紫外成像器件的微透镜阵列,其工作中心波长为350nm,单元透镜F数为3.56。采用组合多层镀膜与剥离的工艺方法制备衍射微透镜阵列,对具体的工艺流程和制备误差进行了分析,测量了衍射微透镜阵列的光学性能。实验结果表明:衍射微透镜阵列的衍射效率为86%,与理论值95%有偏差,制备误差主要来自对准误差和线宽误差。紫外衍射微透镜阵列的整体性能满足了微透镜阵列与紫外成像阵列的单片集成要求。     

用于无模光刻的连续浮雕谐衍射透镜阵列设计

为了获得实时调焦写入以及高的系统分辨力和衍射效率,提出了一种基于连续浮雕谐衍射透镜阵列的无模光刻方法。该方法采用连续浮雕谐衍射透镜阵列作为无模光刻的物镜阵列,在兼顾系统分辨力和衍射效率基础上,由同一衍射透镜阵列实现聚焦写入和检焦;同时利用谐衍射透镜的深浮雕特性调制透镜的环带宽度,降低透镜的制作难度。在分析谐衍射透镜特点以及考虑激光直写制作工艺对连续深浮雕衍射聚焦特性影响的基础上,设计、制作并测试了设计波长为441.6nm,F数为7.5的连续浮雕谐衍射透镜阵列。测试结果表明,该阵列同时具有聚焦写入和检焦功能,且对写入激光和检焦激光的衍射效率均优于70%,有望改善无模光刻的制作质量。     

基于非接触式热压印技术的微透镜阵列制作

为了降低热压印工艺制作微透镜阵列对模具的要求,提出了非接触式热压印工艺制作微透镜阵列,采用了自主研制的纳米压印样机与光刻工艺制作的通孔式不锈钢模具在PMMA表面压印出微透镜阵列,并分析了压印过程中温度、压力、时间等参数对微透镜阵列表面形貌的影响。研究结果表明,利用非接触式热压印工艺可以制作表面形貌好、位置精度高的微透镜阵列,压印时最佳压印温度为140℃~180℃,最佳脱模温度为80℃,最佳压力为1 500 Pa~3 500 Pa,且采用通孔式模具不需要真空,降低了对环境的要求。     

宽范围高对准精度纳米压印样机的研制

传统的光学光刻技术由于受光波波长和数值孔径等因素的限制难于制作特征尺度小于100nm的图案.与传统光刻相比,纳米压印光刻的分辨率不受光的衍射和散射等因素的限制,可突破传统光刻工艺的分辨率极限,因而被认为是一种获得100nm以下图案较好的下一代方法.介绍了自行研制的具有高定位和对准精度的纳米压印样机.利用该样机压印出的纳米级光栅、微凸点阵列、微透镜阵列等纳米结构和微器件的图形质量均匀性良好.该工艺为实现低成本、大批量复制纳米结构创造了条件,在半导体集成电路、微光学、生物和化学分析等微纳结构和器件的制作中有着广泛的应用前景.     

微拱形阵列导光板快速热压成型与微光学应用

微透镜阵列热压精密成型需要时间保温,生产效率较低。因此,提出在模芯加热表面的微沟槽阵列上对聚合物导光板进行热压,使工件热变形的微米尺度表面层流入微沟槽空间内,快速形成微拱形透镜阵列,而保证工件主体不变形。目的是实现高效率和低能耗的微光学透镜阵列热压成型加工。首先,针对导光板表面的微阵列结构和尺寸分析其微光学性能;然后,使用微磨削技术在模芯表面加工出高精度和光滑的微沟槽阵列结构;最后,研究微拱形阵列的快速精密成型工艺及微光学应用。微光学分析显示,微阵列的高度和分布密度对出光面的光照度影响较大。热压工艺实验结果表明,采用深度为104μm和角度为121°的微沟槽阵列模芯,在12 MPa的压力和110℃的温度下,可以在3s内将高度为50μm的3D微拱形阵列导光板快速精密热压成型。本文方法制作的87mm×84mm的导光板,与市面具有2D点阵且高度为8.2μm的丝网印刷导光板相比,光照度提高了21%,光照均匀度提高了27%。本文研究将促进微光学精准设计和制造在LED照明产业的应用。     

导光均光微槽透镜阵列精密磨削及其热压微成型

薄壁LED照明依赖丝网印刷的微阵列导光板,但其表面油墨点阵易老化,且微结构很难优化。因此,在导光板表面设计出高斯分布的空间微槽透镜阵列,并采用数控微磨削技术对其进行加工,替代市面丝网印刷的2D微圆阵列。首先,用微光学原理模拟导光板导光效率和出光均匀度,优化微透镜阵列的形状、尺寸和分布。利用金刚石砂轮微尖端在PMMA导光板表面精密磨削出微透镜阵列,检测其导光效率及均匀性。最后,利用微磨削加工的微阵列成型钢模芯开发微透镜阵列的快速热压微成型工艺。微光学分析表明,微槽透镜阵列比微方形透镜阵列和微半球透镜阵列分别提高导光效率6%和15%。而且,微槽透镜阵列变间距高斯分布比等间距分布提高导光效率32%,提高出光均匀度73%。试验结果显示,微磨削可以控制微槽透镜阵列加工的表面质量和形状精度,应用于LED导光板后比丝网印刷的导光板提高导光效率7%和出光均匀度9%。此外,开发3 s的快速热压微成型工艺,可以加工出变间距和变深度的微槽透镜阵列,比丝网印刷的微圆阵列提高照度26%和出光均匀度49%。因此,微空间结构优化的微槽透镜阵列比丝网印刷的2D微圆阵列可附加出更高的微光学应用价值。     

集成成像系统中高填充率微透镜阵列的设计与加工

针对目前微透镜设计与加工中存在的问题,本文提出了一种大尺寸、高填充率的微透镜阵列设计与加工方法,并成功应用于基于手机屏幕的三维集成成像显示系统。根据焦面模式下的集成成像原理,建立了透镜阵列参数与集成成像显示关键参数的关系,并设计了高填充率透镜阵列的孔径与焦距。采用超精密铣削方法加工出金属母板,通过纳米压印和图形转移复制的方法,在涂有UV固化胶的PET透明膜上得到了高填充率的微透镜阵列膜,并将其应用于基于手机显示屏的集成成像系统。测试结果表明,在5.7英寸全高清手机屏幕上,直接覆盖孔径为0.526mm、焦距为2mm、填充率为100%的透镜阵列,可以实现立体图像出屏距离达4cm、视场角为12.5°的集成成像显示效果。系统的设计与透镜阵列的制作完全满足集成成像要求,裸眼观看立体图像清晰、逼真,系统集成度高,使用方便。     

用于复制柱面微透镜阵列的铸塑工艺

在光刻热熔成型以及电铸复制得到的柱面微透镜阵列镍模板基础上，采用铸塑工艺得到了高质量的PMMA柱面微透镜阵列。本文介绍了静态铸塑的模具设计、工艺过程、参数控制及测试分析。对柱面微透镜阵列的表面形貌分析表明，铸塑复制的面形误差小于0.5μm．     

用于复制柱面微透镜阵列的铸塑工艺

在光刻热熔成型以及电铸复制得到的柱面微透镜阵列镍模板基础上,采用铸塑工艺得到了高质量的 PMMA 柱面微透镜阵列。文中介绍了静态铸塑的模具设计、工艺过程、参数控制及测试分析。微透镜阵列面形误差小于0.5μm。光刻热熔技术可分为三个步骤:①光刻胶板在掩模的遮蔽下进行紫外曝光;②对已曝光的光刻胶板进行显影和清洗;③热熔成型。     

纳米压印技术的研究

介绍了纳米压印技术的原理,讨论了纳米压印中材料的制备及热压印、紫外压印、微接触印刷等3种常用的压印工艺及其关键技术,提出纳米压印技术的研究方向和面临的挑战。     

A promising thermal pressing used in fabricating microlens array

This paper describes a simple and inexpensive technique for designing and fabricating polygon microlens arrays using a thermal pressing process. Polygon microlens array molds were fabricated using lithography and an electroforming process. The microlens patterns were designed on a photomask and transferred to a substrate through photoresist patterning. Electroforming technology was used to convert the photoresist microlens patterns into metallic molds. A hot pressing machine was then used to produce the microlens array in a polycarbonate (PC) substrate. The experimental variables were compression pressure, temperature, and the pressing time. The surface roughness of the produced microlens array was measured using atomic force microscopy (AFM). The average microlens radii of curvature ranged from 315 to 420 μm and the average sag heights were from 2.98 to 4.03 μm, respectively. The experimental result showed that this fabrication process is useful for microlens array production.     

Highly uniform manufacturing method for large-area microlens arrays

The microlens array is a key microstructure component in imaging systems, such as in light field cameras. A resolution of the light field camera can facilitate the use of a small-area microlens array. However, fabricating a large-area microlens array with a highly accurate and consistent surface finish is still difficult and high-cost. A low-cost manufacturing method is proposed in this study, where the mould core of the microlens array is fabricated with high precision and high uniformity by cylindrical ultra-precision diamond turning. The proposed tool path strategy is employed to achieve superior surface quality and avoid the dynamic vibration of an unsmooth path. Light field camera prototypes are developed using a commercial DSLR camera with a fabricated microlens array. The successful performance of the prototypes confirms that the proposed manufacturing method satisfies the application demands of large-area microlens arrays.     

Integration of functionality into polymer-based microfluidic devices produced by high-volume micro-moulding techniques

Microfluidic devices with integrated functional elements have gained increasing attention in recent years. Many prototypes covering a wide range of applications have been fabricated and tested, especially in the fields of chemical and biomedical sciences. Nevertheless, integrated microfluidic devices are still far from being widely used as cost-efficient commercial products, often because they are produced by fabrication methods that are not suitable for mass production. Several methods have been recently introduced for cost-efficient high-volume production of micro-featured plastic parts, such as microinjection moulding and hot embossing. These methods have been widely used for fabricating simple disposable microfluidic chips on a commercial scale, but have not yet been similarly applied for producing integrated microfluidic devices. This review paper aims at presenting the state of the art in integrated microfluidic devices produced by cost-efficient high-volume replication processes. It takes microinjection moulding and hot embossing as its two process examples. Several types of elements are classified according to their functions, defined relative to their physical inputs and outputs. Their level of integration is reviewed. In addition, elements are discussed from a manufacturing viewpoint in terms of being readily produced by replication techniques or by back-end processes. Current and future challenges in integration are presented and discussed.     

热压法快速制作微流控芯片模具

提出了一种微流控芯片模具的快速批量制作方法。应用光刻与湿法腐蚀技术制作玻璃母模,然后采用热压成形技术批量制作聚甲基丙烯酸甲酯(PMMA)阳模,再利用阳模浇模、键合批量制作聚二甲基硅氧烷(PDMS)微流控芯片。结果表明,该法制作的PMMA模具及复制得到的PDMS芯片平整度好、一致性高,其沟道宽度和深度的相对标准偏差分别小于0.5%和1.5%。     

微压印聚合物微流控芯片的传热分析研究

微压印是制造聚合物微流控芯片的主要技术之一,其加工过程中的工艺参数对聚合物微流控芯片成型质量具有重要影响。在聚合物微流控芯片压印成型机理研究基础上,对其压印过程中的热传导进行分析,建立了多层材料一维热传导的模型,并用有限元法进行温度响应求解,进而可获得压印加热时间等工艺参数。     

变温蠕变实验的COP微流控芯片热压制备

采用热压方法制备了COP微流控芯片。由于温度对微结构热压成形的质量影响最大,基于材料的粘弹性特性,通过变温准蠕变实验获得热压参考温度T_r,即从材料玻璃点温度以下开始,以1.5 ℃/min的温升速率,在热压工作压力下热压聚合物基片,通过温度-位移实时采集系统获得材料的温度-形变曲线,曲线的拐点对应的温度即是热压参考温度。实验证明了在该温度下热压成形具有高复制精度和低整体变形,微结构宽度和深度方向的复制精度分别达到97.6%和94.3%。电泳实验和DNA分析实验得出COP芯片具有良好的生物兼容性,适用于生化分析。     

Development of roll-to-roll hot embossing system with induction heater for micro fabrication

In this paper, a hot embossing heating roll with induction heater inside the roll is proposed. The induction heating coil is installed inside a roll that is used as a heating roll of a roll-to-roll (R2R) hot embossing apparatus. Using an inside installed heating coil gives the roll-to-roll hot embossing system a more even temperature distribution on the surface of the heating roll compared to that of previous systems, which used an electric wire for heating. This internal induction heating roll can keep the working environment much cleaner because there is no oil leakage compared to the oiled heating roll. This paper describes the principles and provides an analysis of this proposed system; some evaluation has also been performed for the system. A real R2R hot embossing heating roll system was fabricated and some experiments on micro-pattering have been performed. After that, evaluation has been performed on the results.