Manufacturing of freeform mirror by milling and altering its optical characteristics by ALD SiO2 coating

J. Mutanen, J. Väyrynen, Sini Kivi, Maunu Toiviainen, J. Laukkanen, P. Pääkkönen, T. Itkonen, A. Partanen, Mikko Juuti, M. Kuittinen, K. Mönkkönen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

In this study four aluminium and brass freeform mirrors used as fiber optic spectrometer probes were micro-milled and ALD SiO2 coating was added. Freeform surfaces were designed by combining optical modeling with the mechanical structure. Moore 350 FG ultra precision machine tool was used for milling the freeform parts. To evaluate the surface roughness of the machining one aluminium and one brass freeform mirror also contained a 40 mm radius reference lens. The surface roughness's of parts containing reference lenses were analysed prior to coating them with SiO2 on atomic layer deposition (ALD) device. The uncoated and coated reference lenses were measured with optical profiler. The Ra values of micro-milled reference lenses on uncoated aluminium and brass surfaces were in good correlation to theoretical values. On uncoated aluminium mirror surface roughness Ra was 6.8 nm and for uncoated brass mirror Ra was 5.7 nm. On coated aluminium mirror surface roughness Ra was 5.2 nm and on coated brass mirror Ra was 5.5 nm. For the testing of the spectral functionality of the system the mirrors were coupled to a fiber-optic UV-VIS spectrometer. Spectral measurements were done on coated and uncoated mirrors with several different coloured reflectance standards. Spectral measurements show that SiO2 coating affects the reflectance characteristics of both mirror surfaces while maintaining high reflectivity characteristics.
Original languageEnglish
Title of host publicationProceedings of the
Subtitle of host publication13th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2013
EditorsR. Leach, P. Shore
PublisherEuspen
Pages35 - 38
ISBN (Print)978-095667902-4
Publication statusPublished - 2013
MoE publication typeNot Eligible
Event13th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2013 - Berlin, Germany
Duration: 27 May 201331 May 2013

Conference

Conference13th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2013
Abbreviated titleEUSPEN 2013
CountryGermany
CityBerlin
Period27/05/1331/05/13

Keywords

  • aluminium
  • atomic layer deposition
  • brass
  • coatings
  • lenses
  • milling
  • mirrors
  • optical testing
  • precision engineering
  • reflection
  • spectometers
  • mechanical structures
  • optical characteristics
  • reflectance characteristics
  • reflectance standards
  • spectral measurement
  • ultra-precision machine tools
  • UV-vis spectometer

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  • Cite this

    Mutanen, J., Väyrynen, J., Kivi, S., Toiviainen, M., Laukkanen, J., Pääkkönen, P., Itkonen, T., Partanen, A., Juuti, M., Kuittinen, M., & Mönkkönen, K. (2013). Manufacturing of freeform mirror by milling and altering its optical characteristics by ALD SiO2 coating. In R. Leach, & P. Shore (Eds.), Proceedings of the: 13th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2013 (pp. 35 - 38). Euspen.