18 December 2012 110 years BK7: optical glass type with long tradition and ongoing progress
Author Affiliations +
Proceedings Volume 8550, Optical Systems Design 2012; 85500U (2012); doi: 10.1117/12.981784
Event: SPIE Optical Systems Design, 2012, Barcelona, Spain
Abstract
The SCHOTT glass catalog of 1906 lists the borosilicate crown glass type BK7 for the first time. Since that time it has grown to a high volume glass with equivalents available from all glass manufacturers and became so omnipresent, that many people value it as a cheap bulk commodity type not worthwhile to be looked at closer. This might hold for small thin lenses. However, BK7 can be produced from strip glass format over thick blocks up to large disks of more than 1 m diameter and half a meter thickness. Achieving high homogeneity in thicknesses of 50 mm and above is far from trivial and with increasing thickness it is a challenge even for outstanding glass producers. The present state-of-the-art at SCHOTT is represented by a world record refractive index homogeneity of 1•10-6 peak-to-valley in block glass with more than 200 x 200 mm2 and 100 mm thickness measured in all directions top-to-bottom and in lateral directions. The progress in transmittance led to the introduction of a new quality grade N-BK7HT. The transmittance improvement in the blue-violet spectral range leads to noticeably better twilight vision in use with binocular prisms and image stability in cinema digital projection.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Peter Hartmann, "110 years BK7: optical glass type with long tradition and ongoing progress", Proc. SPIE 8550, Optical Systems Design 2012, 85500U (18 December 2012); doi: 10.1117/12.981784; http://dx.doi.org/10.1117/12.981784
PROCEEDINGS
12 PAGES


SHARE
KEYWORDS
Glasses

Transmittance

Refractive index

Ultraviolet radiation

Optical filters

Visible radiation

Lenses

RELATED CONTENT

Optical three-step binary-logic-gate-based MSD arithmetic
Proceedings of SPIE (October 23 2003)
Electrically tunable NIR spectrometer
Proceedings of SPIE (September 24 1997)
LC SLM with fullerene-dye-polyimide photosensitive layer
Proceedings of SPIE (March 10 2000)
The MTF As An Aid To Focusing Aerial Cameras
Proceedings of SPIE (June 01 1974)
Rayleigh laser guide star wavefront sensing
Proceedings of SPIE (February 04 2002)

Back to Top