Glass microlens arrays for Shack–Hartmann wavefront sensors

Vekshin, M. M.; Levchenko, A. S.; Никитин, А. В.; Никитин, В. А.; Yacovenko, N. A.

doi:10.1088/0957-0233/21/5/054010

Cited by 17 publications

(9 citation statements)

References 8 publications

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“…Microlenses with sub-millimeter diameters are indispensable optical components in a wide variety of miniaturized systems for applications, [1,2] covering optical interconnects, [3,4] Hartman wave front sensing, [5][6][7] beam homogenization, [8,9] visual system of microrobots, [10,11] light emitting diode display, [12] and virtual/augmented reality. [13,14] They can be either refractive or diffractive, depending on how the wavefronts are altered.…”

Section: Microlensesmentioning

confidence: 99%

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Jiang

Guo

et al. 2019

Advanced Materials

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For example, phase profiles required for lensing can be realized by sculpturing dielectric substrates with discretized steps or sloped ridges through photo lithography and reactive ion etching. [18][19][20] These lithography processes make diffractive microlenses more tailorable than refractive microlenses in terms of filling factor and low f-number. However, to achieve high performances, very complex fabrication processes are needed. For example, up to 8 lithography steps and sometimes electron-beam lithography are needed to achieve low f-numbers, [21][22][23] diffraction-limited performance, and over 90% efficiency. [19,[24][25][26] The phase profiles desired for lensing can also be realized with the Pancharatnam-Berry (PB) phases [27,28] by using birefringent materials or metasurfaces with spatially variant optical axes. [13,14,21,[29][30][31][32][33][34] The PB microlenses made of liquid crystals are particularly attractive because of their close to 100% efficiency and switchable focal lengths. [31,33,35,36] Large-sized PB lenses with low f-numbers can be made by holography photopatterning with a refractive master lens, [31] while liquid crystal PB microlenses are still limited to large f-number (>10) [32,33] and no work has been able to show diffraction-limited quality.A range of techniques have been developed in recent years to align liquid crystal molecules into arbitrary designer orientation patterns, which are either based on photoalignments using digital micromirror device (DMD), [37,38] pixel-to-pixel direct laser writing, [30] holography interference [31] and plasmonic photo patterning, [39][40][41] or based on nanostructured surfaces by using nanoimprinting [33] or atomic force microscopy scribing. [42] These techniques have enabled various applications and research ranging from optical devices to programmable origami. [30,33,37,38,[43][44][45][46][47] Here, we show that high-quality microlenses based on PB phases can be designed and made with liquid crystal polymers by using a plasmonic photopatterning technique. The plasmonic photopatterning technique allows for arbitrary molecular orientations encoded in designs of so-called plasmonic metamasks. We designed and fabricated microlenses with a set of focal lengths and f-numbers to test the quality and resolution limit of the plasmonic photopatterning technique. As discussed later, the microlenses with f-number down to 2 requires 1.5 µm of smallest molecular pitches.Microlenses are desired by a wide range of industrial applications while it is always challenging to make them with diffraction-limited quality. Here, it is shown that high-quality microlenses based on Pancharatnam-Berry (PB) phases can be made with liquid crystal polymers by using a plasmonic photopatterning technique. Based on the generalized Snell's law for the PB phases, PB microlenses with a range of focal lengths and f-numbers are designed and fabricated and their point-spread functions and ability to image micrometer-sized particles are carefully characterized. The results show that...

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Section: Microlensesmentioning

confidence: 99%

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Jiang

Guo

et al. 2019

Advanced Materials

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“…Micro-lens arrays are widely applied in homogenizing systems [1,2], light-field imaging [3,4], and Hartmann sensors [5]. The efficiency of energy utilization is an important parameter of a micro-lens array.…”

Section: Introductionmentioning

confidence: 99%

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

Zhang

et al. 2019

Coatings

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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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“…With the development of micro‐optics and micromachining technologies, researches on microlens arrays (MLAs) have attracted increasing attention during two decades. MLAs are widely used in the fields of digital display units , sensors , light source devices , artificial compound eyes , optical fiber interconnects, and optical communications , due to their unique optical properties, small element size and high integration. To satisfy the demand of applications, various researches were carried out to fabricate precise microstructured arrays.…”

Section: Introductionmentioning

confidence: 99%

Design and application of flexible insert for microinjection compression molding polymer microlens arrays with tunable height

Xie

Huang

Chen

2017

Polymer Engineering & Sci

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A flexible insert is assembled using easily available porous plate and flexible polymer film. Then, applying microinjection compression molding technology, a fast and efficient method is proposed for successive, mass and one‐step replication of polymer microlens arrays (MLAs). Orderly MLAs with convex microlenses are successfully prepared without a given micro‐feature on the insert corresponding to that on the MLAs. Interestingly, the flexible films are deformed to arc‐like profiles that match with the shape of the microlenses with different curvatures under the action of different mold compression forces. Hence, by only changing the compression force, a series of high quality MLAs with tunable height and so geometrical‐morphology are molded by one flexible insert. The molded MLAs exhibit average heights of 61.61–86.28 µm by varying the compression force from 90 to 120 kN. The molded MLAs exhibit favorable geometrical‐morphology uniformity and optical properties. The proposed method is an accessible approach to avoid expensive equipment and complicated procedure for manufacturing the mold microfeature. POLYM. ENG. SCI., 58:213–219, 2018. © 2017 Society of Plastics Engineers

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Glass microlens arrays for Shack–Hartmann wavefront sensors

Cited by 17 publications

References 8 publications

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

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

Design and application of flexible insert for microinjection compression molding polymer microlens arrays with tunable height

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