Imprinted and injection-molded nano-structured optical surfaces

Alexander Bruun Christiansen (Invited author), Emil Højlund-Nielsen (Invited author), Jeppe Sandvik Clausen (Invited author), Gideon Peter Caringal (Invited author), N. Asger Mortensen (Invited author), Anders Kristensen (Invited author)

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Inspired by nature, nano-textured surfaces have attracted much attention as a method to realize optical surface functionality. The moth-eye antireflective structure and the structural colors of Morpho butterflies are wellknown examples used for inspiration for such biomimetic research. In this paper, nanostructured polymer surfaces suitable for up-scalable polymer replication methods, such as imprinting/embossing and injection-molding, are discussed. The limiting case of injection-moulding compatible designs is investigated. Anti-reflective polymer surfaces are realized by replication of Black Silicon (BSi) random nanostructure surfaces. The optical transmission at normal incidence is measured for wavelengths from 400 nm to 900 nm. For samples with optimized nanostructures, the reflectance is reduced by 50 % compared to samples with planar surfaces. The specular and diffusive reflection of light from polymer surfaces and their implication for creating structural colors is discussed. In the case of injection-moulding compatible designs, the maximum reflection of nano-scale textured surfaces cannot exceed the Fresnel reflection of a corresponding flat polymer surface, which is approx. 4 % for normal incidence. Diffraction gratings provide strong color reflection defined by the diffraction orders. However, the apperance varies strongly with viewing angles. Three different methods to address the strong angular-dependence of diffraction grating based structural color are discussed.
Original languageEnglish
JournalProceedings of SPIE, the International Society for Optical Engineering
Volume8818
Pages (from-to)881803
Number of pages12
ISSN0277-786X
DOIs
Publication statusPublished - 2013
Event2013 Optics+Photonics - San Diego, California, United States
Duration: 25 Aug 201329 Aug 2013
http://spie.org/optics-photonics.xml

Conference

Conference2013 Optics+Photonics
CountryUnited States
CitySan Diego, California
Period25/08/201329/08/2013
Internet address

Keywords

  • Structural color
  • Diraction gratings
  • Anti-re ective coatings
  • Polymer replication

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