A Microlens Super-Surface Film with Regular Graded Circular Hole-Like Subwavelength Structures for Highly Focusing Strength

Using the fact that a sub-wavelength structure exhibits the same thermal expansion coefficient as a micro-lens array, we design a micro-lens super-surface film with regular circular hole-like subwavelength structures to realize the high performances of central highly focusing strength and short focal length. In addition, based on the Fresnel—Kirchhoff diffraction theory, the influences of subwavelength structural period and height on the focusing performance of a micro-lens are analyzed. Furthermore, the finite-difference time-domain method is utilized to optimize the structural parameters. Via direct laser writing and an inductively coupled plasma process, we fabricated a square micro-lens array consisting of a 1000 × 1000 micro-lens unit with a sub-wavelength structure, and the optical focusing performance was measured in the visible light band. Finally, the experimental results indicate that the focal length is decreased to 15 μm, the focal spot central energy is increased by 7.3%, and the light transmission, enhanced via inserting sub-wavelength structures, corresponds to 3%. This proves that the designed micro-lens array with a regular-graded circular hole-like subwavelength structure can achieve central high focusing and a short focal length. This has applications in several fields of wavefront detection and light field imaging systems.

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An Artificial Compound-Eyes Imaging System Based on Micro-Lens Array with Multiple-Focus

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.933.667 ◽

2014 ◽

Vol 933 ◽

pp. 667-671

Author(s):

Si Di ◽

Peng Liu ◽

Jian Jin

Keyword(s):

Imaging System ◽

Focal Length ◽

Robot Vision ◽

Compound Eyes ◽

Software Module ◽

Lens Array ◽

Multiple Focus ◽

Auto Focus ◽

Micro Lens Array ◽

Micro Lens

Comparing to the single aperture imaging system, Artificial Compound-Eyes (ACE) imaging system has some nice features, such as small size and stereo vision. This paper introduces our multiple-focus ACE imaging system. The system mainly consists of (a) a micro-lens array fabricated by Micro-Electro-Mechanical-System (MEMS) technology, (b) a CMOS chip, (c) a 3D mechanical moving stage, and (d) an auto-focus software module. It can simultaneously observe the object by several channels with different focus, therefore the focal length of the system can be adjusted by selecting different channels. Besides, a software module is developed to carry out auto-focus. The system is applicable to the fields of industry inspection, bio-medical imaging and robot vision.

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Direct laser writing method for micro-lens fabrication on the fiber facet

Journal of Physics Conference Series ◽

10.1088/1742-6596/2015/1/012110 ◽

2021 ◽

Vol 2015 (1) ◽

pp. 012110

Author(s):

A.V. Pisarenko ◽

D.A. Kolymagin ◽

R.D. Zvagelsky ◽

D.D. Merkushev ◽

D. A. Shcherbakov ◽

...

Keyword(s):

Optical Design ◽

Objective Lens ◽

Direct Laser Writing ◽

Fiber System ◽

Laser Writing ◽

Lens Array ◽

Wide Range ◽

Direct Laser ◽

Micro Lens Array ◽

Micro Lens

Abstract We present a way for micro-lens and micro-lens array fabrication on the fiber facet by direct laser writing (DLW) method. The proposed setup for DLW printing on the fiber facet can protect objective lens and makes it possible to safely using a wide range of resists. Microlens fabricated on the single-mode optical fiber facet is demonstrated. Based on lens-on-fiber system we proposed concept of the micro-lenses on baseplate array printed on the multi-core fiber, where each lens is rigidly aligned with the core. One of the possible micro-lenses on the baseplate array is presented and its optical properties such as focal spot size and resolution are investigated. The possible application of the proposed micro-lens array is complex optical elements, such as micro-objectives with optimized optical design. Moreover, suggested freeform lens array can find application in high-accuracy wavefront sensing.

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Simple volume expanding fabrication method for focal length controlled micro-lens array

10.1117/12.2078293 ◽

2015 ◽

Author(s):

Junoh Kim ◽

Muyung Lee ◽

Cheol Joong Kim ◽

Jin Su Lee ◽

Yong Hyub Won

Keyword(s):

Focal Length ◽

Fabrication Method ◽

Lens Array ◽

Micro Lens Array ◽

Micro Lens

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Fabrication of Micro-Lens Array Obtained by Anisotropic Wet Etching of Silicon

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.369.71 ◽

2016 ◽

Vol 369 ◽

pp. 71-76 ◽

Cited By ~ 2

Author(s):

Catalin Parvulescu ◽

Elena Manea ◽

Paul Schiopu ◽

Raluca Gavrila

Keyword(s):

Water Solution ◽

Focal Length ◽

Intermediate Stage ◽

Design Parameters ◽

Sem Images ◽

Etching Depth ◽

Lens Array ◽

Surface Profiles ◽

Micro Lens Array ◽

Micro Lens

This paper presents the fabrication of a micro-lens array surface with a single-mask process and two etching steps with KOH water solution. Numerical analysis of optics was used to determine the optimal design parameters such as curvature sagitta and radius. The dimension of each lens is 20μm x 20μm. We used anisotropic etching of <100> silicon through a circular and squar mask to produce a pyramidal pit formed by four (111) planes. The oxide mask is stripped and the immersion of the sample in the etchant solution favors the etching of (411) plane transforming the pit into a smooth hemispherical cavity. An intermediate stage exists when a wider 19.470 <411> - face pyramid replaces the initial 54.740 inverted pyramid. The dependence of surface roughness on concentration and temperature of KOH is investigated in the range of 25%-40% and 60°C-80°C, respectively, and compared between them. The surface profiles and roughness was characterized by AFM. The etching depth and radius of micro-lens array was obtained from the SEM images and AFM data. Also, the array of concave depressions was directly used as a mould for replication of KER-2500 transparent polymeric silicon from Shin-Etsu with a refractive index n=1.41. The perfectly matched array of micro-lenses can be detached from substrate and used as a local solar concentrator. Optical properties such as the focal length of the plano-convex micro-lens array, obtained by replication, are measured and analyzed.

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