Fabrication of microlenses by plasmaless isotropic etching combined with plastic moulding

Köhler, Uwe; Guber, A.E.; Bier, W.; Heckele, M.

doi:10.1016/0924-4247(96)01164-8

Cited by 29 publications

(12 citation statements)

References 1 publication

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“…M ICROLENSES are key elements in optical microsystems and the majority of them are made of plastic materials in common MEMS (Microelectromechanical Systems) applications. Previously, attempts were made to fabricate threedimensional (3-D) lenses with different micromachining techniques, including lithographic methods [1], [2], reflow of photoresist [3] and isotropic etching of silicon as mold inserts for the plastic molding processes [4], [5]. Surface roughness and the controllability of radius of curvature of the microlens are two major engineering challenges.…”

Section: Microplastic Lens Array Fabricated By a Hot Intrusion Processmentioning

confidence: 99%

“…7. The average radius of curvature is 41.4 m with a standard deviation of 1.05 m. The -number, #, or the inverse of the relative aperture can be calculated as # (4) where is the diameter of the opening hole and is the focal length as derived as (5) In the prototype demonstration, one side of the microlens is flat and the refractive index of the PC material is 1.58 such that the average focal length is 70.7 m and the average f/# is 0.88.…”

Section: A Radius Of Curvature Of the Microlensesmentioning

confidence: 99%

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Microplastic Lens Array Fabricated by a Hot Intrusion Process

Pan

Shen

Lin

2004

J. Microelectromech. Syst.

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A microplastic lens array has been successfully constructed on top of a 500-m-thick PC (Polycarbonate film) by using a micro hot intrusion process. A single-layer LIGA process is used to fabricate the high-aspect-ratio nickel mold insert that has circular hole patterns of 80 m in diameter and 200 m in depth. Under the hot intrusion process, plastic material can be intruded into these circular-shape holes and stopped at desired depth under elevated temperature and pressure to fabricate microlenses. By adjusting the embossing load, temperature and time, the curvature and height of the lens are controllable when the same mold insert is used. The optical properties of these microlenses have been characterized and the average radius of curvature is found as 41.4 m with a standard deviation of 1.05 m. Experimental characterization and theoretical model are conducted and developed for the micro-intrusion process in terms of the radius of curvature and height of the lenses and they correspond well with experimental data within 5% of variations. The focusing capability of the lenses is demonstrated by comparing the images of laser light with and without using the lenses. When the projection screen is placed 200 m away from the lens, the full-width at half-maximum (FWHM) for the lens is 110 m while the original FWHM of the optical fiber is 300 m.[1201]

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Section: Microplastic Lens Array Fabricated By a Hot Intrusion Processmentioning

confidence: 99%

Section: A Radius Of Curvature Of the Microlensesmentioning

confidence: 99%

Microplastic Lens Array Fabricated by a Hot Intrusion Process

Pan

Shen

Lin

2004

J. Microelectromech. Syst.

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“…A lot of researchers tried to fabricate microlenses by manifold processes such as modified LIGA process [1], photoresist reflow process [2], micro intrusion process [3], and isotropic etching process [4]. Nevertheless, most of them seem not to be successful because of its complexity in the fabrication process and difficulty in realizing microlenses array.…”

Section: Introductionmentioning

confidence: 99%

<title>Microlens fabrication using glass transition temperature modification by the LIGA process</title>

Lee

2001

SPIE Proceedings

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A microlens is one of the most important components in optical microsystems. In the last decade, a lot of attempts have been done to fabricate a microlens or microlenses array, however, most of them are relatively complicated in the fabrication process and have difficulties in getting good surface roughness and realizing microlenses array.In this paper, we represent a very simple fabrication technology of the microlens or microlenses array which is based upon a deep X-ray exposure and a thermal treatment of a resist, usually PMMA. The molecular weight and T g of PMMA is reduced when it is exposed to the deep X-ray. The microlens is produced through the effect of surface tension and reflow by adding a thermal treatment on the irradiated PMMA. A configuration of the microlens is determined by parameters such as absorbed X-ray dose on PMMA, heating temperature, and heating time in the thermal treatment.Diameters of the produced microlens range from 100 µm to 1500 µm and their changed heights are between 10 µm and 20 µm.

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“…Up to now, many attempts have been developed including lithographic technique 1 , reflow of photoresists 2 , isotropic etching of silicon plus plastic molding 3 , UV curing of liquid drop [4][5] , UV-induced polymerization 6 , ink-jet printing 7 and so on. The ink-jet printing drop-on-demand technology, mainly developed by MicroFab 7-9 , provides distinct advantages over the conventional photoresist-based technology in the fabrication of micro-optical elements and thus has attracted great attention.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of low-cost polymer microlens array

Jiao

et al. 2006

SPIE Proceedings

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The fabrication technology of refractive microlens array (MLA) with self-assembly of drops of various thermoplastic optical polymer solutions is reported. In order to develop a conventional drop-on-demand type ink-jet printing method for fabricating high quality microlens array, Firstly, we tried to prepare a series of optical polymer inks. These inks compose of high quality optical polymers, polymethylmethacrylate (PMMA), dopant, and functional organic molecules such as laser dye, nonlinear organic dye, and rare earth ion chelates with a suitable organic solvent. Effects of surface tension on the polymer solution drops induced the self-formation of microlenses. This process exhibited a completely self-assembly characteristic without any chemical and photochemical post-treatment. The resulting microlens array displayed diameters varying from 1mm to 5mm and focal lengths from less than one millimeter to a few millimeters. Observation with an atomic force microscope reveals that the surface roughness of the lens is 0.9 nm. The transmittance spectrum of the lens is also measured.

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Fabrication of microlenses by plasmaless isotropic etching combined with plastic moulding

Cited by 29 publications

References 1 publication

Microplastic Lens Array Fabricated by a Hot Intrusion Process

Microplastic Lens Array Fabricated by a Hot Intrusion Process

<title>Microlens fabrication using glass transition temperature modification by the LIGA process</title>

Fabrication of low-cost polymer microlens array

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