Spectralon

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Spectralon is a material made from sintered PTFE , which has an extremely high and uniform degree of reflection in the ultraviolet ( UV ) as well as in the visible ( VIS ) and near infrared ( NIR ) range of the electromagnetic spectrum . It shows Lambertian reflection behavior, i.e. reflects very diffuse or matt. It is used in various forms in optical components, e.g. B. as a reflection standard , in calibration samples , integrating spheres and lasers .

A tablet from Spectralon

properties

The hardness is comparable to high density polyethylene (PE-HD) . It is thermally stable up to over 350 ° C. The material is chemically inert to many bases except for very strong ones such as B. sodium amide or lithium compounds. It is extremely hydrophobic, but absorbs non-polar solvents, fats and oils.

Material contamination can only be removed with difficulty, so the material should be treated with the greatest possible care. Smaller dirt or scratches on the surface can be removed with sand under a water jet. The reflective properties can be largely restored. Investigations into weathering show that there is no damage due to atmospheric UV radiation and no optical or physical damage when stored for long periods in salt water. The reflectance of Spectralon is usually over 99% in the wavelength spectrum between 400 and 1500 nm and over 95% between 250 and 2500 nm. Spectralon is also available in graduated gray tones with a defined lower reflectance. The material contains some carbon. The material shows a strong Lambertian reflection behavior in the range from 257 to 10600 nm, the degree of reflection being greatly reduced at wavelengths above the near infrared. Spectralon absorbs in the range of 2800 nm and between 5400 and 8000 nm. The reflectivity here is below 20%. The material has a damage limit of 4 joules per square centimeter. Therefore, it can only be used for low-power applications.

The Lambertian reflection behavior arises from the structure of the surface and directly below it. A porous network of molecular chains produces multiple internal reflections in the first tenth of a millimeter below the surface. As a result, incident light reflects diffusely. Spectralon can partially depolarize light, but this effect is reduced at large angles of incidence.

Applications

Spectralon is available in three quality levels: optical quality, laser and aerospace quality. Optical grade Spectralon is highly reflective and ideally diffuse. The laser quality class has the same physical properties, but has been optimized for use in optical pumps with a different material mixture. It is used in various “side-pumped” lasers. Spectralon, which has been classified as space grade , is used in space travel for remote sensing applications in satellites.

history

Spectralon has been sold by Labsphere since 1986 .

Web links

Individual evidence

  1. a b c d e Georgi T. Georgiev, James J. Butler: Long-term calibration monitoring of Spectralon diffusers BRDF in the air-ultraviolet . In: Applied Optics . tape 46 , no. 32 , 2007, p. 7892-7899 , doi : 10.1364 / AO.46.007892 .
  2. Albert E. Stieg man; Carol J. Bruegge; Arthur W. Springsteen: Ultraviolet stability and contamination analysis of Spectralon diffuse reflectance material . In: Optical Engineering . tape 32 , no. 4 , 1993, p. 799 , doi : 10.1117 / 12.132374 .
  3. Kenneth J. Voss, Hao Zhang: Bidirectional reflectance of dry and submerged Labsphere Spectralon plaque . In: Applied Optics . tape 45 , no. 30 , 2006, pp. 7924-7927 , doi : 10.1364 / AO.45.007924 .
  4. Archived copy ( Memento of the original from February 27, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.systems-eng.co.jp
  5. Hans F. Grahn, Paul Geladi (Ed.): Techniques and Applications of Hyperspectral Image Analysis . 1st edition. Wiley, 2007, ISBN 978-0-470-01086-0 , pp. 133 .
  6. a b http://www.photonicsonline.com/download.mvc/Optimization-Of-Spectralon-Through-Numerical-0002
  7. ^ Robert Edward Fischer, Biljana Tadic-Galeb: Optical system design . 2nd Edition. Mcgraw-Hill, 2008, ISBN 978-0-07-147248-7 , pp. 534 .
  8. Dennis H. Goldstein, David B. Chenault, J. Larry Pezzaniti: Polarimetric characterization of Spectralon (=  Proceedings of SPIE . Vol. 3754). July 1999 ( dtic.mil [PDF]).