Fabrication of hard-coated optical absorbers with microstructured surfaces using etched ion tracks: Toward broadband ultra-low reflectance

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2015-08, Vol.356-357, p.154-159
• Main Authors: Amemiya, Kuniaki, Koshikawa, Hiroshi, Yamaki, Tetsuya, Maekawa, Yasunari, Shitomi, Hiroshi, Numata, Takayuki, Kinoshita, Kenichi, Tanabe, Minoru, Fukuda, Daiji
• Format: Article
• Language: English
• Subjects: Broadband; Coating; Etching; Hard coated; Ion tracks; Low reflectance; Microstructured; Microstructured surfaces; Optical absorber; Reflectance; Reflectivity; Spectral reflectance; Wavelengths
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/j.nimb.2015.05.002

•A hard-coated optical absorber with microstructured surface was fabricated.•Etched ion tracks coated with diamond-like carbon were used.•The reflectance was below 2% for wavelengths in the 400–1400nm range.•Fabricated optical absorber exhibited temporal durability and mechanical stability.•Further improvement of the design and process will yield reflectance of ∼0.1%. Broadband low reflectance materials have various applications in the field of optical energy management; however, materials with ultra-low reflectance (below 0.1%) have been considered as mechanically delicate. We have developed a novel hard-surface optical absorber with microstructured, diamond-like carbon coated ion tracks on CR-39 plastic substrate. The spectral reflectance of the first prototype was below 2% for wavelengths ranging from 400nm to 1400nm; moreover, the optical absorber had mechanically hard surface and exhibited temporal durability. Choosing the appropriate design of the surface structure and coating layer is likely to reduce the reflectance to the order of 0.1%. This technique yields easy-to-handle broadband ultra-low reflectance absorbers.