scholarly journals Fabrication and Optical Characterization of Polymeric Aspherical Microlens Array Using Hot Embossing Technology

2021 ◽  
Vol 11 (2) ◽  
pp. 882
Author(s):  
Yanlong Li ◽  
Kangsen Li ◽  
Feng Gong
Keyword(s):  
Process Parameters ◽  
High Efficiency ◽  
Low Cost ◽  
Microlens Array ◽  
Hot Embossing ◽  
Molding Pressure ◽  
Microlens Arrays ◽  
Aspheric Lens ◽  
Molding Temperature ◽  
Holding Temperature

Hot embossing has been widely used in fabricating microlens arrays because of its low cost, high efficiency, and high quality. The process parameters such as molding temperature, molding pressure, and holding temperature affect the microlens array’s replication quality. This work selected the stainless steel S136H tool steel as the mold material to process an aspheric microlens array structure through ultra-precision milling. Polymethyl methacrylate (PMMA) microlens arrays with different surface replication were prepared by controlling the molding temperature, molding pressure, and holding temperature. By analyzing the surface quality, contour replication, and optical imaging of hot-embossed samples, the optimal molding temperature of PMMA for optimal replication of aspheric lens arrays was determined as 130 °C. Besides, the internal elastic recovery of PMMA affected the dimensional accuracy and optical performance of the lens. The results showed that, at the molding pressure of 400 N and the holding temperature of 60 °C, the surface defects were eliminated, and the aspheric lens array had perfect replication with a profile deviation of only 4 μm. The aspheric microlens array with good quality was eventually achieved by these optimal process parameters, which provides a foundation for producing aspheric microlens arrays in a low-cost and high-efficiency way.

scholarly journals Fabrication of Multiscale-Structure Wafer-Level Microlens Array Mold

2019 ◽  
Vol 9 (3) ◽  
pp. 487 ◽  
Author(s):  
Shuping Xie ◽  
Xinjun Wan ◽  
Xiaoxiao Wei
Keyword(s):  
Low Cost ◽  
Form Factors ◽  
Cost Effective ◽  
Microlens Array ◽  
Practical Method ◽  
Reduced Form ◽  
Wafer Level ◽  
Polycrystalline Aluminum ◽  
Microlens Arrays ◽  
Multiscale Structure

The design and manufacture of cost-effective miniaturized optics at wafer level, usingadvanced semiconductor-like techniques, enables the production of reduced form-factor cameramodules for optical devices. However, suppressing the Fresnel reflection of wafer-level microlensesis a major challenge. Moth-eye nanostructures not only satisfy the antireflection requirementof microlens arrays, but also overcome the problem of coating fracture. This novel fabricationprocess, based on a precision wafer-level microlens array mold, is designed to meet the demandfor small form factors, high resolution, and cost effectiveness. In this study, three different kinds ofaluminum material, namely 6061-T6 aluminum alloy, high-purity polycrystalline aluminum, and purenanocrystalline aluminum were used to fabricate microlens array molds with uniform nanostructures.Of these three materials, the pure nanocrystalline aluminum microlens array mold exhibited auniform nanostructure and met the optical requirements. This study lays a solid foundation for theindustrial acceptation of novel and functional multiscale-structure wafer-level microlens arrays andprovides a practical method for the low-cost manufacture of large, high-quality wafer-level molds.

scholarly journals Effects of Electrospinning Parameters on the Microstructure of PVP/TiO2 Nanofibers

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1616
Author(s):  
Wan-Tae Kim ◽  
Dong-Cheol Park ◽  
Wan-Hee Yang ◽  
Churl-Hee Cho ◽  
Won-Youl Choi
Keyword(s):  
Process Parameters ◽  
Organic Solar Cells ◽  
High Efficiency ◽  
Low Cost ◽  
Fluid Velocity ◽  
Average Diameter ◽  
Electrospinning Process ◽  
Electrical And Optical Properties ◽  
Tio2 Nanofibers ◽  
The Many

Titanium dioxide has excellent chemical, electrical, and optical properties, as well as good chemical stability. For that reason, it is widely used in many fields of study and industry, such as photocatalysts, organic solar cells, sensors, dental implants, and other applications. Many nanostructures of TiO2 have been reported, and electrospinning is an efficient practical technique that has a low cost and high efficiency. In various studies on improving performance, the researchers created nanofibers with suitable microstructures by changing various properties and the many process parameters that can be controlled. In this study, PVP/TiO2 nanofibers were fabricated by the electrospinning process. The diameters of the nanofibers were controlled by various parameters. To understand the effects on the diameter of the nanofibers, various process parameters were controlled: the molecular weight and concentration of the polymers, deionized water, applied voltage, fluid velocity, and concentration of titanium precursor. The average diameter of the PVP nanofibers was controlled in a range of 42.3 nm to 633.0 nm. The average diameter of the PVP/TiO2 nanofibers was also controlled in a range of 63.5 nm to 186.0 nm after heat treatment.

scholarly journals Noncontact Microembossing Technology for Fabricating Thermoplastic Optical Polymer Microlens Array Sheets

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xuefeng Chang ◽  
Dan Xie ◽  
Xiaohong Ge ◽  
Hui Li
Keyword(s):  
Mechanical Characteristics ◽  
Optical Glass ◽  
Low Cost ◽  
Microlens Array ◽  
Production Costs ◽  
Efficient Production ◽  
Promising Technique ◽  
Element Analysis ◽  
Microlens Arrays ◽  
Optical Polymer

Thermoplastic optical polymers have replaced traditional optical glass for many applications, due to their superior optical performance, mechanical characteristics, low cost, and efficient production process. This paper investigates noncontact microembossing technology used for producing microlens arrays made out of PMMA (polymethyl methacrylate), PS (polyStyrene), and PC (polycarbonate) from a quartz mold, with microhole arrays. An array of planoconvex microlenses are formed because of surface tension caused by applying pressure to the edge of a hole at a certain glass transition temperature. We studied the principle of noncontact microembossing techniques using finite element analysis, in addition to the thermal and mechanical properties of the three polymers. Then, the independently developed hot-embossing equipment was used to fabricate microlens arrays on PMMA, PS, and PC sheets. This is a promising technique for fabricating diverse thermoplastic optical polymer microlens array sheets, with a simple technological process and low production costs.

Fast Generation of Micro-Channels on Cylindrical Surfaces by Elliptical Vibration Texturing

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Ping Guo ◽  
Yong Lu ◽  
Pucheng Pei ◽  
Kornel F. Ehmann
Keyword(s):  
Process Parameters ◽  
High Efficiency ◽  
Low Cost ◽  
Pattern Generation ◽  
Depth Of Cut ◽  
Channel Formation ◽  
Structured Surfaces ◽  
Elliptical Vibration ◽  
Micro Channels ◽  
Elliptical Vibration Texturing

Micro-structured surfaces are assuming an ever-increasing role since they define the ultimate performance of many industrial components and products. Micro-channels, in particular, have many potential applications in micro-fluidic devices, micro heat exchangers, and friction control. This paper proposes an innovative vibration-assisted machining method to generate micro-channels on the external surface of a cylinder. This method, referred to as elliptical vibration texturing, was originally developed by the authors to generate dimple patterns. It uses the modulation of the depth-of-cut by tool vibrations to create surface textures. The most promising features of the proposed method are its high efficiency, low cost, and scalability for mass production. It is shown that with proper combinations of the process parameters the created dimples start to overlap and form channels. An analytical model is established to predict channel formation with respect to the overlapping ratios of the dimples. Channel formation criteria and expressions for channel geometries are given along with a channel generation map that relates channel geometry to the process parameters. Experimental results are given to verify the model. A further example of micro-pattern generation is also given to showcase the flexibility of the process.

Nano-modified indium tin oxide incorporated with ideal microlens array for light extraction of OLED

2019 ◽  
Vol 7 (13) ◽  
pp. 3958-3964 ◽  
Author(s):  
Jun-Gui Zhou ◽  
Xiao-Chen Hua ◽  
Yang-Kai Chen ◽  
Yu-Yang Ma ◽  
Chen-Chao Huang ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
High Efficiency ◽  
Microlens Array ◽  
Light Extraction ◽  
Microlens Arrays

Nano-modified ITO anode with low haze incorporated with ideal microlens arrays is achieved for high-efficiency OLED.

A Microlens Array with Different Focal Lengths Fabricated by Roll-To-Roll UV Lithography

2018 ◽  
Vol 26 (2) ◽  
pp. 155-159
Author(s):  
Huichun Ye ◽  
Lianguan Shen ◽  
Mujun Li ◽  
Likai Li
Keyword(s):  
Optical Properties ◽  
Low Cost ◽  
Microlens Array ◽  
Master Mold ◽  
Pdms Mold ◽  
Microlens Arrays ◽  
Array Pattern ◽  
Roll To Roll ◽  
Ultra Precision ◽  
Micro Structures

A simple, highly efficient and low cost roll-to-roll (R2R) UV imprinting lithography facility was achieved for fabricating micro-structures. Firstly, a novel microlens array with focuses distributed on a curved surface was designed and analyzed by an optical software ZEMAX. Then an ultra-precision diamond machine was applied to generate the freeform microlens array features on the master mold, and a belt-type polydimethylsiloxane (PDMS) mold with a microlens array pattern was prepared from the machined master mold. The R2R process was employed to replicate the microlens arrays, followed by an evaluation of their profiles and optical properties. Our experiments demonstrate that the applied method is reliable and efficient for producing the polymeric microlens arrays.

scholarly journals Optimization of molding process parameters for CF/PEEK composites based on Taguchi method

2021 ◽  
Vol 30 ◽  
pp. 263498332110018
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Tensile Strength ◽  
Process Parameters ◽  
Holding Time ◽  
Thermoplastic Composites ◽  
Molding Pressure ◽  
Molding Process ◽  
Molding Temperature ◽  
Transverse Tensile ◽  
Peek Composite ◽  
Transverse Tensile Strength

In this article, nine groups of laminates were prepared according to the Taguchi L9(33) test array to study the influence of three process parameters, including molding pressure, molding temperature, and holding time on the performance of unidirectional carbon fiber/polyetheretherketone (CF/PEEK) laminates. A differential scanning calorimetry test was employed to select a reasonable process parameters range. The transverse tensile strength of the laminates was measured, and the fiber–matrix interfacial bonding behavior of the tested samples was analyzed by scanning electron microscopy. The results showed that the significance of factors to transverse tensile strength were molding temperature, holding time, and molding pressure in sequence. The optimal molding process parameters for CF/PEEK composite laminate were molding temperature of 400°C, molding pressure of 3 MPa, and holding time of 30 min. The optimization results were meaningful for the extension and application of thermoplastic composites.

A Novel Method for Fabrication of the Biomimetic Shark-Skin Coating

2011 ◽  
Vol 239-242 ◽  
pp. 3014-3017 ◽  
Author(s):  
Xin Han ◽  
Juan Wang
Keyword(s):  
High Efficiency ◽  
Skin Effect ◽  
Low Cost ◽  
Hot Embossing ◽  
Skin Sample ◽  
Shark Skin ◽  
Submicron Scale ◽  
Good Repeatability ◽  
Novel Method ◽  
First Time

The shark-skin effect motivated from the dermal surface morphology of sharks hastens the imitation and manufacture of the non-smooth drag reduction bionic coating based on shark skin. The fabrication of the bionic shark-skin coating with life-sized scale-like microstructure was presented in this paper. Using hot embossing technology, the direct micro replication of the microstructure on shark skin was investigated for the first time. Modeled after the shark skin sample, the negative structure was directly replicated and printed on PMMA flat plate in the hot embossing process, relied on which the bionic shark-skin coating made of silica gel was fabricated in the end. The preliminary experiment results indicate that this method is a high precision, high throughput, high efficiency and low cost way to fabricate bionic microstructure in micron and submicron scale with good repeatability and availability.

scholarly journals Optimization of Process Parameters for Friction Materials Using Multi-Criteria Decision Making: A Comparative Analysis

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1570
Author(s):  
Dinesh Shinde ◽  
Hasan Öktem ◽  
Kanak Kalita ◽  
Shankar Chakraborty ◽  
Xiao-Zhi Gao
Keyword(s):  
Heat Treatment ◽  
Decision Making ◽  
Comparative Analysis ◽  
Case Studies ◽  
Process Parameters ◽  
Surface Hardness ◽  
Molding Pressure ◽  
Multi Criteria Decision Making ◽  
Friction Materials ◽  
Molding Temperature

Friction materials, mainly made of reinforced composites, should possess excellent physical and tribological properties, such as a higher coefficient of friction, minimum wear, adequate surface hardness, and higher porosity for various automotive brake applications. Attainment of those properties greatly depends on the settings of different input parameters, such as molding pressure, temperature and time, temperature and time of heat treatment/sintering, etc., during the processing of friction materials. In this article, four multi-criteria decision-making (MCDM) tools, i.e., technique for order of preference by similarity to ideal solution (TOPSIS), evaluation based on distance from average solution (EDAS), VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR), and multi-objective optimization on the basis of ratio analysis (MOORA) are applied to identify the optimal parametric combinations for two different friction materials. A comparative analysis of the derived results suggests the same optimal parametric mixes for all the MCDM techniques for both case studies. Thus, for the considered case studies, the optimal parametric combinations as molding time = 8 min, molding temperature = 175 °C, molding pressure = 27 MPa, sintering time = 10 h and sintering temperature = 225 °C, and molding pressure = 27.90 MPa, molding temperature = 170 °C, curing time = 8 min, and heat treatment time = 1 h, respectively, would help in attaining the most desired properties of friction materials. Improvements in the predicted response values prove the efficacy of the adopted MCDM techniques in determining the optimal combinations of various process parameters for friction materials.

Realization of Mass Production of Microlens Array by Hot Embossing on Silicon Substrate

2010 ◽  
Vol 139-141 ◽  
pp. 1562-1565
Author(s):  
Xi Qiu Fan
Keyword(s):  
High Resolution ◽  
High Throughput ◽  
Silicon Substrate ◽  
Mass Production ◽  
Low Cost ◽  
Microlens Array ◽  
Hot Embossing ◽  
High Fidelity ◽  
Optical Performance ◽  
Large Area

Tradition lithographic techniques to produce micrlens array are complicated and time consuming. Due to the capability to replicate nanostructures repeatedly in a large area with high resolution and uniformity, hot embossing has been recognized as one of the promising approaches to fabricate microlens array with high throughput and low cost. This paper introduces processes to realize fabricating microlens array in mass production by direct hot embossing on silicon substrate. The mold is fabricated by multi-photolithography and etching steps and polymethyl methacrylate (PMMA) is chosen as the resist. Processes include coating, heating, pressing, etc. Fidelity and optical performance of the embossed microlens array were measured. High fidelity and fine optical performance of the embossed microlens array demonstrate the possibility of hot embossing to fabricate microlens array in mass production.

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