Fabrication of a micro-tip array mold using a micro-lens mask with proximity printing

In this study, a mold for a micro-tip array is fabricated using a microlens array mask with proximity exposure. The micro-tip array uses a microlens array mask with geometrical optics. Light passing through a microlens is focused at the focal points. There is microlens on the mask and the pattern that results from the light passing through the mask is directly projected onto the photoresist surface. A concave profile is developed using a positive photoresist and the remaining photoresist microstructures are formed after the development process. By changing the distance between the mask and the photoresist and the radius of curvature of the microlens, various tip shapes can be fabricated. The exposure gap is calculated using the microlens array mask and the geometry of the mold of micro-tip array is established using the irradiance absorption maps for the different levels. These methods respectively use the model of the positive photoresist and optical software. When electroforming a metallic micro-tip copy of the patterned photoresist, masters are created. The metal micro-tip array is used membrane probe card.     

微尖的两种制作工艺

描述各向异性腐蚀结合键合和各向异性腐蚀结合电镀来制作微尖的方法,利用这两种方法制作出了针尖直径小于25nm的金字塔形微尖,通过实验证明:这是两种有良好可控性和工艺要求不高的制作方法。微尖的成功制作为传感器微型化提供了一种很有潜力的新型检测方式,解决了检测的灵敏度问题。     

Gravitational lensing by gravitational waves

Gravitational lensing by a gravitational wave is considered. We notice that, although the final and initial directions of photons coincide, there occurs a displacement between the final and initial trajectories. This displacement is calculated analytically for a plane gravitational wave pulse. Observational estimates are discussed.     

聚合物光栅光波导器件的微复制技术

采用纳米压印微复制技术方法,研制了一种新型的聚合物柔性光栅光波导敏感器件,该器件可用于介入式医用导管的微弯挠曲监测或类似场合的微变形监测.重点阐述了聚合物柔性光栅光波导器件的微复制模具和器件微复制的工艺方法,并对制备工艺技术中的关键技术问题进行了讨论,讨论了测试光纤耦合一体化光栅波导器件的工艺方法.最后利用硅微模具和紫外固化介质材料,成功制备出了截面尺寸为4 μm×20 μm、光栅周期为0.75 μm的聚合物柔性光栅光波导器件.     

Fabrication of the monolithic polymer–metal microstructure by the backside exposure and electroforming technology

Monolithic polymer–metal microstructures can be fabricated on the silicon or glass substrate using two kinds of photoresists and electroforming technologies for the inkjet and microfluidic application. However, it suffers from the high shrinkage problem of first SU8 resist after exposure and post exposure baking. This paper reports a novel approach to solve the shrinkage problem by introducing backside exposure of first SU8 resist for the fabrication of the monolithic polymer–metal microstructure. In combination with the light absorption layer coating on the unexposed SU8 resist, metal seed layer deposition, frontside exposure for second JSR resist on the seed layer and the nickel (Ni) electroforming together with release process, we have demonstrated a high physical resolution of 1,200 dpi monolithic Ni nozzle plate with negligible shrinkage. It also has the advantages of low cost and high resolution for the improvement of the traditional bonding of polymer and metal nozzle plate, which is generally in need of a complex alignment to stick the metal nozzle plate and dry film polymer on the heating chip together.     

Fabrication of hollow polymer microstructures using dielectric and capillary forces

Electric Field Assisted Capillarity is a novel one-step process suitable for the fabrication of hollow polymer microstructures. The process, demonstrated to work experimentally on a microscale using Polydimethylsiloxane (PDMS), makes use of both the electrohydrodynamics of polymers subject to an applied voltage and the capillary force on the polymers caused by a low contact angle on a heavily wetted surface. Results of two-dimensional numerical simulations of the process are discussed in this paper for the special case of production of microfluidic channels. The paper investigates the effects of altering key parameters including the contact angle with the top mask, the polymer thickness and air gap, the permittivity of the polymer, the applied voltage and geometrical variations on the final morphology of the microstructure. The results from these simulations demonstrate that the capillary force caused by the contact angle has the greatest effect on the final shape of the polymer microstructures.

     

Fabrication of nanomechanical optical devices with aligned wafer bonding

 This paper reports on a new method for making some types of integrated optical nanomechanical devices. Intensity modulators as well as phase modulators were fabricated using several silicon micromachining techniques, including chemical mechanical polishing and aligned wafer bonding. This new method enables batch fabrication of the nanomechanical optical devices, and enhances their performance. Received: 13 May 1998 / Accepted: 30 June 1998     

Thermal-deformation analysis of a polymer micro-mirror optical device

This paper analyzes the thermal deformation in SU-8 polymer materials when subjected to different fabricating parameters and exposed to a high power light source for long durations for 45° micro-mirror applications. By experimentally optimizing the fabrication process, new fabricating technologies for micro-optical components can be developed. During the fabrication process, a polymer-based material is subjected to different soft bake, post exposure bake (PEB), hard baking temperatures; also, the baking times and exposure dosages were varied. Any of these variables can change the thermal stability of the material’s bonding energy and dynamic molecular behavior. There have not been many studies on the thermal deformation of a micro-mirror structure. A thermal dilatometer DIL-402C was used in this study to measure the thermal stability and determine changes in the material phase of SU-8 material. After optimizing the process parameters and finding that the inclined surface roughness was 49 nm, the thermal deformation was found to be 25 ppm (at 100°C).     

直流提取技术对OOK调制的自由空间光通信系统的性能改进

自由空间光通信技术因优点显著目前已经获得了极大的发展,其具有免频谱许可证、安全传输、大容量和低部署成本的特点。然而,光信号在经历大气信道的传输过程中会受到大气湍流效应的影响而发生衰减和波动,这种现象称为闪烁效应,会大大降低系统的传输性能。研究了提取信号中直流分量作为连续波参考光的技术,并将其应用到自由空间光通信系统中。得出了在信道为对数正态分布模型下的误码率模拟结果,并详细分析了通过提取直流信号作为参考波后的性能改进。     

Electro‐optical parameters of FLC layers stabilized by a typical polymer net

Abstract— A typical polymer net with microcells of different sizes (from 25 × 25 to 200 × 200 μm) was formed by using a lithographic process, both on glass and flexible polymeric substrates. To investigate the influence of polymeric walls on FLC‐display cell operation, the typical electro‐optical parameters of FLC layers — light transmission and scattering, optical contrast ratio and response time — were measured under different conditions, such as display cell preparation and processing, driving voltage, microcell dimensions, and temperature.     

Fabrication of suspended electrokinetic microchannels from directly written sacrificial polymer fibers

Freely suspended microchannels with diameters ranging from 4 to 100?μm were fabricated by utilizing directly written PMMA fibers as sacrificial structures. These precisely oriented fibers served as scaffolds around which thin cylinders of glass were deposited (via sputtering), followed by a conformal coating of Parylene to augment the mechanical integrity of the structures. After coating, the PMMA fibers were dissolved to yield suspended, hollow conduits that were hydrophilic and robust. The freely suspended channels were loaded with a buffer solution containing charged particles, which were subsequently electrokinetically manipulated and velocities quantified using microparticle image velocimetry (μPIV). Mobilities within 1.3?% of those observed in conventional, planar microchannels were recorded.     

Fabrication of two dimensional high aspect ratio polymer photonic crystal laser

Photonic crystals have attracted much attention from researchers because of the control over the propagation and emission of light and particular optical properties. In this paper, we reported on the design, fabrication and test of a two-dimensional polymer photonic crystal laser. First of all, a two-dimensional polymer photonic crystal laser with a triangle-lattice structure was described. Rhodamine 6G doped in PMMA was chosen as the gain material. Then, plane wave method based on the Maxwell equations was utilized to calculate the distribution of the photonic band gap. We calculated the band structure of a triangle lattice photonic crystal with a low refractive index. High resolution electron beam lithography combined with electroplating was used to fabricate the silicon nitride mask. A high aspect ratio two-dimensional photonic crystal laser was fabricated by X-ray lithography in one-step process to overcome the limitation of the thickness by the conventional methods to realize a real two-dimensional laser. Meanwhile, processes of sample preparations and fabrication were optimized in order to avoid the oxidation of the gain material and reduce the diffraction effect on the structures.     

Fabrication and characterization of machined 3D diffractive optical elements

The production of three dimensional blazed grating structures based on ultra-precision machining is an up-to-date issue. Hence, in the development of manufacturing technologies technology-related failure modes are generated due to structural variations. These failure errors must be recorded in cause and effect and then characterized by their type in order to achieve the optimum quality. This paper addresses the influence of processing parameters on the shape-persistence and hence on the grating quality and explains the possibility of detection and classification of them.     

The properties of free-standing epoxy polymer multi-mode optical waveguides

The paper reports on the fabrication and characterisation of free-standing multimode optical epoxy polymer waveguides consisting of a core made of EpoCore and EpoClad polymer cladding and cover protection layers. The 50 × 50 μm² rectangular waveguides are intended for short-reach optical interconnection and optimised for an operating wavelength of 850 nm. The waveguides of the proposed shapes were fabricated by a standard photolithography process on a silicon substrate provided with a Poly(vinyl alcohol) thin layer. The free-standing structure was then achieved by peeling the deposited EpoClad/EpoCore/EpoClad structures of that substrate. The optical scattering losses of the created planar waveguides, measured by the fibre probe technique at 632.8 and 964 nm, were 0.30 dB cm⁻¹ at 632.8 nm and 0.17 dB cm⁻¹ at 964 nm. Propagation optical loss measurements for rectangular waveguides were performed by the cut-back method and the best samples had optical losses below 0.55 dB cm⁻¹ at 850 and 1310 nm.

     

Remote sensing technique for near-surface wind by optical images of rough water surface

The study of a new remote-sensing technique for the investigation of near-surface wind fields is an important oceanographic problem. This article is focused on a new method of recording wind fields by the analysis of optical images of sea surface and range–time–intensity images (RTI images) of the sea surface. An RTI image constructed from optical profiles of the sea surface is an optical analogue of a side-looking radar image of the sea surface but has a higher spatial resolution and some possibility for remote sensing of sea roughness. It is possible to form RTI images with a range from some tens of metres to tens of kilometres, depending on the spatial resolution needed. A set of original optical devices for recoding RTI images using linear arrays of CCD-photodiodes was created. An analytical model of sea surface radiance for visible light was developed taking into account the polarization of light and shadowing of surface waves for grazing view geometry. The principle of remote sensing of near-surface winds by its manifestations on a waved surface under grazing angles based on a comparison of measured and modelled surface radiance is discussed. Investigations of near-surface wind field features in internal reservoirs and various regions of the seas during the last few years have been conducted by optical systems. The structure of near-surface wind fields, eddies, wind fronts, and katabatic wind flows for ranges from hundreds of metres to some tens of kilometres was recorded and analysed. Derived data of optical monitoring of water surfaces may serve for future investigations of near-surface wind features.     

Fabrication of high aspect-ratio polymer microstructures for large-area electronic portal x-ray imagers

Megavoltage X-ray imaging performed during radiotherapy is the method of choice for geometric verification of patient localization and dose delivery. Presently, such imaging is increasingly performed using electronic portal imaging devices (EPIDs) based on indirect detection active matrix flat panel imagers (AMFPIs). These devices use a scintillating phosphor screen in order to convert incident X-rays into optical photons, which are then detected by the underlying active matrix photodiode array. The use of a continuous phosphor introduces a trade-off between X-ray quantum efficiency and spatial resolution, which limits current devices to use only 2% of the incident X-rays. This trade-off can be circumvented by “segmented phosphor screens”, comprising a two-dimensional matrix of optically isolated cell structures filled with scintillating phosphor. In this work we describe the fabrication of mm-thick segmented phosphor screens using the MEMS (micro-electro-mechanical-system) polymer SU-8. This method is capable of being extended to large-area substrates.     

Fabrication of CNT field‐emitter array using a polymer insulator

Abstract— The fabrication process of a carbon‐nanotube (CNT) field‐emitter array (FEA) having a polymer insulator is reported. This polymer material is suitable for a large‐sized FEA because of its coating property and thermal stability. These features contribute to the display‐image uniformity, the tolerance to the thermal‐sealing process, etc. A new method of forming via holes on the insulator instead of gate holes has been developed. The method uses a spin‐wet‐etching (SWE) technique instead of the typical reactive‐ion‐etching (RIE) method. The RIE method damages and contaminates the CNT at the end of the etching process. However, the SWE technique ensures fine gate hole configurations with little under‐cut without any damage nor contamination. An FEA panel 1.5 in. on the diagonal was fabricated by using the method. The FEA showed good emission uniformity with proper surface treatment of the CNT.