01-25-2011, SCHOTT North America
SCHOTT expands portfolio of optical glasses with “Ultra High Transmittance”
Advances are important for large tele zoom lenses in cinema, broadcasting and digital camera applicationsJanuary 25, 2010 (at SPIE Photonics West in San Francisco Booth #1601) – Today SCHOTT Advanced Optics, a division of SCHOTT North America, Inc., announced the expansion of its portfolio of optical glasses with outstanding internal transmittance. In October, SCHOTT released a set of new “high grade transmittance” (HT) glasses and additionally introduced a new suffix “HTultra” for glasses with outstanding transmittance behavior compared to other glasses offered on the market. These new “HTultra” glasses are N-SF57HTultra and N-SF6HTultra with improved transmittance compared to previous versions and to competing glass types.
Transmittance is one of the most important properties of optical glass. It is especially important at the blue-violet spectral range of such glasses because high refractive index glasses usually lack good transmittance in this region purely due to physical reasons. SCHOTT is able to surpass the physical limitations given by the chemical composition of the optical glass to stretch those limits by optimizing the melting conditions and the purity of the raw materials.
Several years ago, SCHOTT improved the internal transmittance of high refractive index glasses and released new glass types with the suffix HT for “high grade transmittance.” N-SF6HT and N-SF57HT are two examples from this product line. Whereas the internal transmittance curves of standard optical glasses in the datasheets comprise median values for the glass types, HT glass internal transmittance curves show limit values for the internal transmittance in the visible spectrum.
Since then SCHOTT has continuously worked on the expansion of its offering on glasses with high transmittance. The newly released glass type will be renamed from SF57HHT to SF57HTultra. Other new high refractive index HT glasses are N-LASF45HT and N-LASF9HT.
As the melting technology of optical glasses has advanced over the years, SCHOTT has improved and adapted the catalog transmittance curves of several optical glasses. These glasses are: N-LASF31A, N-LAF21, N-LAF33, N-LAF34, N-SF4 and N-LAK7. Optical glasses with improved transmittance in the blue-violet spectral range are suitable for large tele zoom lenses in cinema, broadcasting and digital single-lens reflex (DSLR) camera applications. They also improve the image quality of sports optics applications like binoculars. In cinema digital projection applications with increasing light fluxes, the internal transmittance is important for prisms with long optical path length to reduce heating induced image aberrations. For such applications SCHOTT developed the prism glasses N-BK7HT and N-SK2HT with an improved transmittance compared to the standard glass type.
In general all applications with long optical path length inside can take advantage of the improved transmittance. HT and HTultra glasses from SCHOTT are the enablers of high quality products now and in the future.
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