Selective surface smoothening of 3D micro-optical elements

Schift, Helmut; Chidambaram, Nachiappan; Altana, Mirco; Kirchner, Robert

doi:10.1117/12.2256358

Cited by 3 publications

(3 citation statements)

References 22 publications

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“…This is extremely favorable for all types of phase modulation optical devices as diffractive optical elements, kinoforms or recently demonstrated birefringent optical retarders. [119][120][121][122] In the case of discrete multi-level phase elements, isotropic shrinkage reduces achievable pixel sizes, reducing scattering losses, and increasing resolution of the devices, most notably reducing the height of individual steps in longitudinal direction. In the case of birefringent retarders or photonic devices, reduction in size, allows to achieve sub-wavelength periodicity lattices, needed for efficient single diffraction order operation throughout visible range.…”

Section: Geometry Distortion and Feature Sizementioning

confidence: 99%

Fabrication of Glass‐Ceramic 3D Micro‐Optics by Combining Laser Lithography and Calcination

Balčas

Malinauskas

Farsari

et al. 2023

Adv Funct Materials

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This perspective is an overview of a recent direction in optical 3D printing, where polymerization of crosslinkable materials and nanomaterial fillers can be guided to the final structures and new composites via high temperature annealing (HTA). Defining 3D nano/micro‐structures by ultrafast laser direct writing and tailoring their precursor composition with subsequent tunability of the final properties during 750–1500 °C HTA step takes place at the large surface‐to‐volume ratio conditions favoring efficient pyrolysis and calcination, which are required for exchange of chemical materials/gases between glass/ceramic phase and surrounding. Previously, unexplored inorganic material formation conditions in terms of fast thermal quenching, composition mixing and surface tension guided formation can be harnessed by glass making for creation of new materials endowed with preferable technical properties. An immediate application perspective for a high durability, integrated, and active 3D micro‐optics is foreseen.

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Section: Geometry Distortion and Feature Sizementioning

confidence: 99%

Fabrication of Glass‐Ceramic 3D Micro‐Optics by Combining Laser Lithography and Calcination

Balčas

Malinauskas

Farsari

et al. 2023

Adv Funct Materials

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“…[415][416][417] In the polymeric material, a vertical gradient material contrast, which is expressed by molecular weight Mw/glass transition temperature Tg, can be created through the 172 nm UV light, realizing a selective surface reflow limited in a superficial region without effect on the bulk. [418][419][420][421] As shown in Figure 6k, the surface roughness of TPL printed mold can be reduced to 10 nm in its PMMA replica. [422] roughness and spot distance.…”

Section: Surface Roughnessmentioning

confidence: 99%

Two‐Photon Polymerization Lithography for Optics and Photonics: Fundamentals, Materials, Technologies, and Applications

Wang

Zhang

Ladika

et al. 2023

Adv Funct Materials

115

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The rapid development of additive manufacturing has fueled a revolution in various research fields and industrial applications. Among the myriad of advanced three-dimensional printing techniques, two-photon polymerization lithography (TPL) uniquely offers a significant electron microscope (SEM) images of SMP structures before and after programming and after recovery, respectively. Reproduced under terms of the CC-BY license. [114] Copyright 2021, The Authors, published by Nature Publishing Group. b) Stiff SMPs for high-resolution reversible nanophotonics. I-II) The deformed and recovered nanopillars under optical microscope and SEM, respectively. Reproduced with permission. [115] Copyright 2022, American Chemical Society. c) Vapor-responsive photonic arrays. I-IV) Optical image of a grid array in air, in water vapors ~ 20 s, saturation with water vapors ~ 88s, and after the gas flow stopped, respectively.Reproduced under terms of the CC-BY license. [116] Copyright 2021, The Authors, published by Royal Society of Chemistry. d) SEM image of a 40-layer face-cantered-cubic photonic structure printed by SU-8. Reproduced with permission. [117] Copyright 2004, Nature Publishing Group. e) SEM image of helices with an axial pitch of 800 nm and a radius of 800 nm fabricated by the two-step absorption photoresist. Reproduced with permission. [118]

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“…Instead of improving surface roughness by time-consuming and design-specific direct-writing strategies of 3-D lithographic methods, we chose a postprocessing method based on surface selective thermal reflow. [25][26][27][28] We quickly recapitulate this method for the modification of polymer surfaces being published earlier 28 and especially compare in this work the two strategies of postprocessing and direct-writing for surface smoothening. The principle of smoothening is based on a process known as thermally activated selective topography equilibration (TASTE).…”

Section: Introductionmentioning

confidence: 99%

Benchmarking surface selective vacuum ultraviolet and thermal postprocessing of thermoplastics for ultrasmooth 3-D-printed micro-optics

2018

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State-of-the-art, polymeric, refractive micro-optics simultaneously require an ultrasmooth threedimensional (3-D) surface and a precise geometry for excellent optical performance with minimal stray light. In earlier work, we have established a surface finishing process for thermoplastic polymer master structures that is only effective on the surface and does not affect the designed optical geometry, thus enabling polishing without touching. Therewith, the high curvature corners of a 50-μm-tall optical diffuser device were maintained while the surface roughness was reduced to about 10-nm root mean square. For this, 3-D master structures were first fabricated by direct write laser-lithography with two-photon polymerization. The master structures were replicated into poly(methyl methacrylate) through a poly(dimethyl siloxane) intermediate replication stamp. Finally, all structures were surface-polished by selective high-energy photon exposure and thermal postprocessing. In this work, we focus on the comparison of the surface smoothening using either postprocessing or dedicated direct writing strategies. For this comparison, strategies for modifying the exposed voxel size and the writing discretization being the primary source of roughness were tested by sweeping the laser exposure dose for two different resist materials and objectives. In conclusion, the postprocessing smoothening resulted in a lower roughness compared to a direct writing strategy-even when 50-nm vertical discretization steps were usedand still enabled 10 times shorter writing times.

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Selective surface smoothening of 3D micro-optical elements

Cited by 3 publications

References 22 publications

Fabrication of Glass‐Ceramic 3D Micro‐Optics by Combining Laser Lithography and Calcination

Fabrication of Glass‐Ceramic 3D Micro‐Optics by Combining Laser Lithography and Calcination

Two‐Photon Polymerization Lithography for Optics and Photonics: Fundamentals, Materials, Technologies, and Applications

Benchmarking surface selective vacuum ultraviolet and thermal postprocessing of thermoplastics for ultrasmooth 3-D-printed micro-optics

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