A high numerical aperture, polymer-based, planar microlens array (original) (raw)
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Monolithic polymer microlens arrays with high numerical aperture and high packing density
ACS applied materials & interfaces, 2015
This work reports a novel method for monolithic fabrication of high numerical aperture polymer microlens arrays (high-NA MLAs) with high packing density (PD) at wafer level. The close-packed high-NA MLAs were fabricated by incorporating conformal deposition of ultrathin fluorocarbon nanofilm and melting the cylindrical polymer islands. The NA and PD of hemispherical MLAs with a hexagonal arrangement increase up to 0.6 and 89%, respectively. The increase of NA enhances the lens transmission securing the beam width down to 1.1 μm. The close-packed high-NA MLAs enable high photon collection efficiency with signal-to-noise ratio greater than 50:1.
Low-cost polymeric microlenses array
2002
A process for large-scale fabrication of an array of divergent cylindrical micro lenses is presented. The device was fabricated employing a silicon-based micromachined mould combined with a replication technique of PMMA spin casting and a suiting post baking cycle. The resulting device is capable to split an incoming laser beam at a high fan-out angle. Key-words microlenses array, silicon-based micromould, polymer-based microlenses
A New Approach to Polymeric Microlens Array Fabrication Using Soft Replica Molding
IEEE Photonics Technology Letters, 2004
This letter reports a new fabrication method of polymeric, nonspherical microlens arrays based on the soft replica molding process, employing elastomeric molds with desired microlens patterns. The elastomeric molds are made of polydimethylsiloxane (PDMS) and prepared through an innovative process consisting of excimer laser microdrilling, spin coating, and soft replica molding. The demonstrated microlens arrays, made of polymethylmethacrylate, include three footprints with diameters of 50, 100, and 150 m. Results show the microlens arrays have both good surface uniformity and high-quality optical properties. The resulting microlenses have focal lengths varying from tens to hundreds of micrometers and present low-number ranging between 0.8 and 1.5. The facts that the PDMS elastomeric molds are chemically inert and that all processing steps are executed in ambient environment and at low temperature render the proposed approach a potential method for mass production of microlens arrays.
Journal of Micromechanics and Microengineering, 2007
We present a complete and precise quantitative characterization of the different process steps used in an elastomeric inverse moulding and vacuum casting technique. We use the latter replication technique to fabricate concave replicas from an array of convex thermal reflow microlenses. During the inverse elastomeric moulding we obtain a secondary silicone mould of the original silicone mould in which the master component is embedded. Using vacuum casting, we are then able to cast out of the second mould several optical transparent poly-urethane arrays of concave refractive microlenses. We select ten particular representative microlenses on the original, the silicone moulds and replica sample and quantitatively characterize and statistically compare them during the various fabrication steps. For this purpose, we use several state-of-the-art and ultra-precise characterization tools such as a stereo microscope, a stylus surface profilometer, a non-contact optical profilometer, a Mach-Zehnder interferometer, a Twyman-Green interferometer and an atomic force microscope to compare various microlens parameters such as the lens height, the diameter, the paraxial focal length, the radius of curvature, the Strehl ratio, the peak-to-valley and the root-mean-square wave aberrations and the surface roughness. When appropriate, the microlens parameter under test is measured with several different measuring tools to check for consistency in the measurement data. Although none of the lens samples shows diffraction-limited performance, we prove that the obtained replicated arrays of concave microlenses exhibit sufficiently low surface roughness and sufficiently high lens quality for various imaging applications.
Optics express, 2015
Plano-convex microlens arrays of organic-inorganic polymers with tailored optical properties are presented. The fine-tuning of each microlens within an array is achieved by confining inkjet printed drops of the polymeric ink onto pre-patterned substrates. The lens optical properties are thus freely specified, and high numerical apertures from 0.45 to 0.9 and focal lengths between 10 μm and 100 μm are demonstrated, confirming theoretical predictions. Combining nanoimprint lithography approaches and inkjet printing enables using the same material for the microlenses and their substrates, improving the optical performances. Microlens arrays with desired specifications are printed reaching yields up to 100% and high lens reproducibility with standard deviations of the apparent contact angle under 1° and of the numerical apertures and focal lengths under 6%. Microlens arrays involving lenses with different characteristics, e.g. multi focal length, and thus focal planes separated by only ...
Flat polymeric microlens array
Optics Communications, 2006
A polymer-based flat microlens array is demonstrated. Within each pixel of the array, the polymer presents a circular central-symmetric inhomogeneous orientation. Pixel with such a structure behaves a lens-like character. A suitable amount of liquid crystal mixed in the polymer host can improve not only the lens flexibility but also the lens performance. Moreover, the polymer-based microlens array has the advantages of real planar surface, ultra-thin thickness, and can be designed with any aperture size.
We demonstrate the cost-effective and facile method of fabricating close-packed microlens arrays using photoinduced two-dimensional (2-D) surface relief structures as original templates. 2-D surface relief structures are produced by successive inscription of two beams interference patterns with different grating vectors on azopolymer films. The employed exposure dose of 1 st inscription stage and 2 nd inscription stage are optimized to obtain symmetrical modulation heights. These photoinduced 2-D surface relief structures on azopolymer films are used directly to mold PDMS, and PDMS molds were then transferred onto photopolymer to imprint microlens arrays. Using this method, tetragonally and hexagonally close-packed microlens arrays are successfully fabricated in rapid and cost-effective way.
Applied Optics, 2001
High-performance polymer microlens arrays were fabricated by means of withdrawing substrates of patterned wettability from a monomer solution. The f-number ͑f # ͒ of formed microlenses was controlled by adjustment of monomer viscosity and surface tension, substrate dipping angle and withdrawal speed, the array fill factor, and the number of dip coats used. An optimum withdrawal speed was identified at which f # was minimized and array uniformity was maximized. At this optimum, arrays of f͞3.48 microlenses were fabricated with one dip coat with uniformity of better than ⌬f͞f ϳ Ϯ3.8%. Multiple dip coats allowed for production of f͞1.38 lens arrays and uniformity of better than ⌬f͞f ϳ Ϯ5.9%. Average f # s were reproducible to within 3.5%. A model was developed to describe the fluid-transfer process by which monomer solution assembles on the hydrophilic domains. The model agrees well with experimental trends.
Tailored polymer microlenses on treated glass surfaces
Applied Physics Letters, 2007
Integrating arrayed biosensors ͑biochips͒ or micro-and nanofluidic devices with readout systems is an important step towards their realization in lab-on-a-chip devices. To this end, we present a straightforward method of fabricating polymer microlenses in precise locations, with desired optical characteristics, using a combination of two methods: surface energy tuning using low-energy electron irradiation, to control the numerical aperture, and time-controlled nanofountain pen deposition of polymer microlenses, to control the focal length. The authors demonstrate the tuning of focal length between 8 and 20 m with numerical apertures between 0.16 and 0.26.
A New Process For Manufacturing Arrays Of Microlenses
6th Mtg in Israel on Optical Engineering, 1989
The need for microlenses with a wide -range of focal lengths from 10µ to 100mm and with a diameter varying from 10µ to 1mm lead to the development of various techniques which are able to generate these lenses in a photoresist substrate. The existing techniques are reviewed and a new one proposed. In this technique a positive or negative photoresist layer is exposed to a tailored light intensity distribution. After development of the photoresist, its surface is identical to the spatial intensity light distribution. Photoresist with an index of refraction of n =1.6 in the visible spectrum, can be used as a lens.