Schott provides optical glasses with the lowest tolerances for refractive index and Abbe number

Schott’s new optical glasses have a tolerance level of 0.5, which are particularly well-suited for use in high precision lenses. These extremely narrow tolerances are obtained by closely controlling the melting and annealing processes with the help of state-of-the art techniques used in glass manufacturing.

Schott is now the first manufacturer to offer special optical glasses with a tolerance level of 0.5. The maximum deviation from the nominal values listed in the datasheet is only ± 0.0001 with the refractive index nd and ± 0.1 % with the Abbe number νd with this new level of quality. This means Schott has the narrowest optical tolerances available in the market.
Glasses of the tolerance level 0.5 are particularly well-suited for use in high precision lenses. To achieve the best possible resolution, several lenses must be precisely in tune with each other. The narrow optical position of the glasses helps to improve the quality of the lenses used in inspection systems in industry or microscopy.
In response to the growing demand, Schott now offers the following preferred fine annealed and prepared glass types in the tolerance level 0.5 from stock: N-BK7 and N-BK7HT, N-KZFS4 and N-KZFS4HT, N-KZFS5, N-KZFS8, N-PK51 and N-FK51A. Other glasses of the tolerance level 0.5 are available upon request. The range of preferred glasses now available supports a wide range of applications. For instance, highly homogeneous N-BK7HT is a typical prism glass. Or N-KZFS, with its abnormal partial dispersion, is used together with the fluorphosphate glass N-FK51A that is known for its low dispersion to perform precise apochromatic colour corrections.
Schott is able to achieve these extremely narrow tolerances by closely controlling the melting and annealing processes with the help of state-of-the art techniques used in glass manufacturing. Then, these glass products are measured extremely precisely and further referenced inside a V-block refractometer at Schott.
Schott is an international technology group with more than 125 years of experience in the areas of speciality glasses and materials and advanced technologies. Schott ranks number one in the world with many of its products. Its core markets are the household appliance, pharmaceuticals, electronics, optics, solar power, transportation and architecture industries. The Schott Group maintains close proximity to its customers with manufacturing and sales units in 35 different countries. Its workforce of around 16,000 employees generated worldwide sales of approximately EUR 2 billion for the 2011/2012 fiscal year. Schott AG, with its headquarters in Mainz, Germany, is owned by the Carl Zeiss Foundation.