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High-resolution imaging and fast number estimation of suspended particles using dewetted polymer microlenses in a microfluidic channel. Micron 2021; 151:103148. [PMID: 34562815 DOI: 10.1016/j.micron.2021.103148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 12/25/2022]
Abstract
We have fabricated polymer micro-lens array by self-organized dewetting inside the microchannel, which shows remarkable enhancement in the resolution, contrast and more than 10 times add-on magnification to a microscope. These lenses are demonstrated to resolve sub-micrometer features and detect moving micro-particles when suspension is flown in a microchannel. Polystyrene (PS) micro-lenses are fabricated on a polydimethylsiloxane (PDMS) substrate using the controlled dewetting of PS thin film then this PDMS substrate is used to close the microchannel with inverted micro-lenses on it. An aqueous suspension of polystyrene particles is flown through the microchannel and we have observed the particles through an optical microscope. Focusing and magnification through PS micro-lenses is analyzed to get a quantitative estimate of the particle number density in the solution. This method offers a promising low-cost high throughput solution for determining the approximate number density of flowing particles or suitably stained biological cells. Particularly in a pathology lab it can tremendously increase detection limit by enabling visibility of sub-micrometer pathogens using a standard laboratory microscope.
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2
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Liang Y, Zhu T, Xi M, Abbasi HN, Fu J, Su R, Song Z, Wang K, Wang H. Fabrication of concave microlenses on a diamond by a spin coating process. OPTICS EXPRESS 2020; 28:9320-9326. [PMID: 32225541 DOI: 10.1364/oe.383640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/02/2020] [Indexed: 06/10/2023]
Abstract
In this study, to fabricate diamond concave microlenses in a simple manner, an approach that combines a spin coating process with subsequent dry etching was demonstrated. First, photolithography was used to produce cylindrical holes in the photoresist layer on the diamond surface. Then, another photoresist was spin coated to fill the holes, and the concave structures with meniscus shapes were then obtained because of centrifugal force and interfacial tension. Finally, diamond concave microlenses were formed by transferring photoresist concave structures onto a diamond substrate using a dry etching technique. The fabricated diamond microlens exhibits a low surface roughness with nanometers as well as high-quality imaging and focusing performances, which is expected to have a wider range of potential applications under harsh and special conditions.
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Kirner R, Béguelin J, Eisner M, Noell W, Scharf T, Voelkel R. Improvements on the uniformity of large-area microlens arrays in Fused Silica. OPTICS EXPRESS 2019; 27:6249-6258. [PMID: 30876213 DOI: 10.1364/oe.27.006249] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
The uniformity of large microlens arrays in Fused Silica is governed by the production process. It comprises photolithographic patterning of a spin-coated layer of photoresist on a 200mm wafer with a molten resist reflow process and subsequent dry etching. By investigating systematic influences throughout the production process we show how to steer the lens production process with a single degree of freedom to improve the uniformity of the final microlens array. To enable this we describe the optical performance of microlenses with only one parameter: the principal aberration component. It is the result of principal component analysis of the chosen optical merit function. We present the case of manufactured microlens arrays with element sizes >100 mm × 100 mm where uniformity was improved by a factor of 2.
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Park HG, Khang DY. High-performance light diffuser films by hierarchical buckling-based surface texturing combined with internal pores generated from physical gelation induced phase separation of binary polymer solution. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.06.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Valyukh S, Slobodyanyuk O. Assessment of minimum permissible geometrical parameters of a near-to-eye display. APPLIED OPTICS 2015; 54:6526-6533. [PMID: 26367839 DOI: 10.1364/ao.54.006526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Light weight and small dimensions are some of the most important characteristics of near-to-eye displays (NEDs). These displays consist of two basic parts: a microdisplay for generating an image and supplementary optics in order to see the image. Nowadays, the pixel size of microdisplays may be less than 4 μm, which makes the supplementary optics the major factor in defining restrictions on a NED dimensions or at least on the distance between the microdisplay and the eye. The goal of the present work is to find answers to the following two questions: how small this distance can be in principle and what is the microdisplay maximum resolution that stays effective to see through the supplementary optics placed in immediate vicinity of the eye. To explore the first question, we consider an aberration-free magnifier, which is the initial stage in elaboration of a real optical system. In this case, the paraxial approximation and the transfer matrix method are ideal tools for simulation of light propagation from the microdisplay through the magnifier and the human eye's optical system to the retina. The human eye is considered according to the Gullstrand model. Parameters of the magnifier, its location with respect to the eye and the microdisplay, and the depth of field, which can be interpreted as the tolerance of the microdisplay position, are determined and discussed. The second question related to the microdisplay maximum resolution is investigated by using the principles of wave optics.
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Gallego S, Fernández R, Márquez A, Ortuño M, Neipp C, Gleeson MR, Sheridan JT, Beléndez A. Two diffusion photopolymer for sharp diffractive optical elements recording. OPTICS LETTERS 2015; 40:3221-3224. [PMID: 26176434 DOI: 10.1364/ol.40.003221] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Photopolymers as recording media are widely used in optical applications. In such materials, changes in the phase of the transmittance function are generated during exposure due to refractive index and thickness modulations. These changes arise primarily as a consequence of photopolymerization and mass transport processes. Characterizing polymers' performance, for example, quantifying the value of monomer diffusion, is therefore very important. Applying index matching, the volume and surface optical effect are separated in an acrylamide/polyvinylalcohol (AA/PVA) material. Using a simplified model that includes the effects of the holes produced during polymerization, both hole and monomer diffusion are analyzed. The analysis presented indicates higher material sensitivity than previously estimated. The results also indicate the possibility of recording sharper diffractive optical elements profiles, like blazed gratings, having diffraction efficiencies higher than 80%.
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Takehara H, Ohta Y, Motoyama M, Haruta M, Nagasaki M, Takehara H, Noda T, Sasagawa K, Tokuda T, Ohta J. Intravital fluorescence imaging of mouse brain using implantable semiconductor devices and epi-illumination of biological tissue. BIOMEDICAL OPTICS EXPRESS 2015; 6:1553-1564. [PMID: 26137364 PMCID: PMC4467724 DOI: 10.1364/boe.6.001553] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 03/16/2015] [Indexed: 06/04/2023]
Abstract
The application of the fluorescence imaging method to living animals, together with the use of genetically engineered animals and synthesized photo-responsive compounds, is a powerful method for investigating brain functions. Here, we report a fluorescence imaging method for the brain surface and deep brain tissue that uses compact and mass-producible semiconductor imaging devices based on complementary metal-oxide semiconductor (CMOS) technology. An image sensor chip was designed to be inserted into brain tissue, and its size was 1500 × 450 μm. Sample illumination is also a key issue for intravital fluorescence imaging. Hence, for the uniform illumination of the imaging area, we propose a new method involving the epi-illumination of living biological tissues, and we performed investigations using optical simulations and experimental evaluation.
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Affiliation(s)
- Hiroaki Takehara
- Institute for Research Initiatives, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Yasumi Ohta
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Mayumi Motoyama
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Makito Haruta
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Mizuki Nagasaki
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Hironari Takehara
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Toshihiko Noda
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Kiyotaka Sasagawa
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Takashi Tokuda
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
| | - Jun Ohta
- Institute for Research Initiatives, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192,
Japan
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Jiang C, Li X, Tian H, Wang C, Shao J, Ding Y, Wang L. Lateral flow through a parallel gap driven by surface hydrophilicity and liquid edge pinning for creating microlens array. ACS APPLIED MATERIALS & INTERFACES 2014; 6:18450-18456. [PMID: 25348103 DOI: 10.1021/am506067v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This letter proposes a surface-energy driven process for economically creating polymer microlens array (MLA) with well controllable curvatures. When a UV-curable prepolymer flows into a cell constructed by multiple holes on a top template and a flat substrate, since the edge pinning of the contact line, an array of curved air/prepolymer interface forms around each microhole of the template. Then a UV-radiation of the bulk prepolymer leads to a solid microlens array. The curvature of the air/prepolymer interface can be controlled by choosing materials with different interface free energy or varying the gap height mechanically.
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Affiliation(s)
- Chengbao Jiang
- Micro-/Nano-technology Research Center State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 West Xianning Road, Xi'an, Shaanxi 710049, China
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Chen F, Deng Z, Yang Q, Bian H, Du G, Si J, Hou X. Rapid fabrication of a large-area close-packed quasi-periodic microlens array on BK7 glass. OPTICS LETTERS 2014; 39:606-9. [PMID: 24487877 DOI: 10.1364/ol.39.000606] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Large-area close-packed microlens arrays (MLAs) are highly desirable for structured light and integrated optical applications. However, efficient realization of ultralarge area MLAs with a high fill factor is still technically challenging, especially on glass material. In this Letter we propose a high-efficiency MLA fabrication method using single-pulsed femtosecond laser wet etch and close-packed quasi-periodic concave MLAs consisting of three million units fabricated on silica glass within an hour. The fabricated MLAs are demonstrated to have extreme optical smoothness (∼8.5 nm) by an atomic force microscope. It has also been demonstrated that the profile of the quasi-periodic concave structures could be easily tuned by changing the laser scanning speed or the pulse energy. Additionally, the optical performances of the MLA diffusers were investigated by using sharp focusing, high-resolution imaging, and flat-top illumination.
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Li X, Tian H, Ding Y, Shao J, Wei Y. Electrically templated dewetting of a UV-curable prepolymer film for the fabrication of a concave microlens array with well-defined curvature. ACS APPLIED MATERIALS & INTERFACES 2013; 5:9975-9982. [PMID: 23902897 DOI: 10.1021/am402043u] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This paper presents an economic method, based on electrically templated dewetting of a UV-curable prepolymer, for fabricating a concave microlens array (MLA) of high quality and high density. In our strategy, a voltage is applied to an electrode pair consisting of a conductive substrate coated with a UV-curable prepolymer film and a microhole-arrayed silicon template, sandwiching an air gap, to dewet the prepolymer film into a curved air-liquid interface. At or beyond a critical voltage, the curved prepolymer can be pulled quickly into contact with the protrusive underside of the silicon template. Contact of the prepolymer with the template can be detected by monitoring the leaky current in the polymer, followed by a UV curing of the prepolymer. Finally, by separating the mold from the solidified polymer, a concave MLA is obtained. The curvature of the MLA can be well-defined simply by changing the air gap between the mold and prepolymer film. Besides, the dewetting strategy results in a much smaller adhesion area between the mold and solidified polymer structures, which allows for easy separation of the mold from the MLA in a large-area operation.
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Affiliation(s)
- Xiangming Li
- Micro- and Nano-manufacturing Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 Xianning Road, Xi'an 710049, People's Republic of China
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11
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de la Barrière F, Druart G, Guèrineau N, Taboury J, Gueugnot A, Huc V. Fabrication of concave and convex potassium bromide lens arrays by compression molding. APPLIED OPTICS 2012; 51:4936-4944. [PMID: 22858931 DOI: 10.1364/ao.51.004936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 06/01/2012] [Indexed: 06/01/2023]
Abstract
A new simple and cost-effective method has been developed for the fabrication of both plano-convex and plano-concave lens arrays with potentially important sag heights. The process is based on the use of potassium bromide (KBr) powder. At ambient temperature and under pressure, KBr powder is compressed on a molding die with the desired shape to form a solid lens array. The quality of the lens arrays has been assessed, and we present the first image produced by a converging KBr lens array.
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Liu R, Ye Z, Park JM, Cai M, Chen Y, Ho KM, Shinar R, Shinar J. Microporous phase-separated films of polymer blends for enhanced outcoupling of light from OLEDs. OPTICS EXPRESS 2011; 19 Suppl 6:A1272-A1280. [PMID: 22109624 DOI: 10.1364/oe.19.0a1272] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Thin microporous films were formed by dropcasting a toluene solution containing various ratios of polystyrene:polyethylene glycol blends on a glass substrate, with OLEDs on the ITO that coated the opposite side of that substrate. We demonstrate for the first time that such easily-fabricated films with surface and bulk micropores in the index-matching polystyrene can serve as random microlens-like arrays to improve forward OLED light extraction by up to ~60%. A theoretical interpretation of the angular emission profile of the device, considering the geometrical change at the substrate/air interface and the scattering by the pores within the films, was established in excellent agreement with the experiments. The use of such blended thin films provides an economical method, independent of the OLED fabrication technique, for improving the outcoupling efficiency.
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Affiliation(s)
- Rui Liu
- Ames Laboratory - USDOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
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13
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Merola F, Miccio L, Coppola S, Vespini V, Paturzo M, Grilli S, Ferraro P. Exploring the capabilities of Digital Holography as tool for testing optical microstructures. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/3dres.01(2011)3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Li X, Ding Y, Shao J, Liu H, Tian H. Fabrication of concave microlens arrays using controllable dielectrophoretic force in template holes. OPTICS LETTERS 2011; 36:4083-4085. [PMID: 22002393 DOI: 10.1364/ol.36.004083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This Letter presents a method for fabricating concave microlens arrays of UV-curable polymer by using the dielectrophoresis (DEP) force. The DEP force, generated by a voltage between the patterned conductive template and substrate, acting on the polymer-air interface, can drive the dielectric liquid polymer into the template holes and change the shape of the polymer-air interface. The upper polymer surface of fabricated microlens is super smooth, which can reduce optical noise. The upper surface geometry is measured approximately as parabolic in general, which can lead to a negligible spherical aberration, compared to spherical surfaces.
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Affiliation(s)
- Xiangming Li
- State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, China
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Kim JY, Choi KC. Improvement in Outcoupling Efficiency and Image Blur of Organic Light-Emitting Diodes by Using Imprinted Microlens Arrays. ACTA ACUST UNITED AC 2011. [DOI: 10.1109/jdt.2011.2121053] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Chen F, Liu H, Yang Q, Wang X, Hou C, Bian H, Liang W, Si J, Hou X. Maskless fabrication of concave microlens arrays on silica glasses by a femtosecond-laser-enhanced local wet etching method. OPTICS EXPRESS 2010; 18:20334-43. [PMID: 20940925 DOI: 10.1364/oe.18.020334] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A simple and efficient technique for large-area manufacturing of concave microlens arrays (MLAs) on silica glasses with femtosecond (fs)-laser-enhanced chemical wet etching is demonstrated. By means of fs laser in situ irradiations followed by the hydrofluoric acid etching process, large area close-packed rectangular and hexagonal concave MLAs with diameters less than a hundred of micrometers are fabricated within a few hours. The fabricated MLAs exhibit excellent surface quality and uniformity. In contrast to the classic thermal reflow process, the presented technique is a maskless process and allows the flexible control of the size, shape and the packing pattern of the MLAs by adjusting the parameters such as the pulse energy, the number of shots and etching time.
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Affiliation(s)
- Feng Chen
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education, School of Electronics & Information Engineering, Xi'an Jiaotong University, Xi'an, China.
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Li K, Liu HD, Zhou Q, McIntosh D, Campbell JC. SiC avalanche photodiode array with microlenses. OPTICS EXPRESS 2010; 18:11713-11719. [PMID: 20589031 DOI: 10.1364/oe.18.011713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A simple technique to incorporate microlenes with small photodiode arrays is demonstrated and analyzed. Using this method, the fill factor was increased from 2.6% to 22.4% for a two by two array. Simulation results are also shown. The photocurrent with microlens was approximately 8.6 times larger than without the microlens, which is consistent with simulation results.
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Affiliation(s)
- Kejia Li
- Department of Electrical and Computer Engineering, University of Virginia, 351 McCormick Road, Charlottesville, Virginia 22904, USA.
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