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Available in 48-hour express service*
N-BK7 is a very pure universal optical glass made by SCHOTT. It is one of the most common standard glass types used to produce high-quality optics, mainly for the visible spectrum. The relatively hard borosilicate crown material consists of the purest raw ingredients. It contains very few inclusions and is almost free of bubbles.
The high material quality is a primary technical reason why N-BK7 glass is often the number one choice for optical windows, lenses, and prisms. Its smooth transmission and low absorption in the entire visible wavelength range are crucial features for numerous optical applications.
Unpolished N-BK7 raw materials are available with a maximum length of about 350 mm and a thickness of around 70 mm. Larger glass dimensions are sometimes possible on request. N-BK7 belongs to the optical block glasses and does not come as smooth glass sheets. Hence, sawing, grinding, polishing, and shaping are always necessary production steps to fabricate optics from BK7. Due to the material's stable chemical properties and high stain resistance, special treatment of the glass blanks is unnecessary before grinding and polishing.
If you want to request optical windows, substrates, wafers, or other components made of N-BK 7 material with individual dimensions, please select a thickness from the table in the specifications or click on the following button.
Note: If you are searching for optical glass materials with similar purity that can transmit ultraviolet light, please visit our fused silica and quartz glass web page.
BK7 raw material comes in glass blocks. Hence, it is not available as glass sheets with standard thicknesses. Therefore, the glass thickness always needs to be specified individually.
To offer our customers the best possible service and high availability, we continually polish the glass thicknesses shown in the following table. We can manufacture these thicknesses quickly and, if required, even as part of our express service for dimensions up to approximately 200 mm by 200 mm.
Please click on glass thickness to request a quote:
Thickness (mm) |
Tolerance |
|
---|---|---|
0.50 | ±0.025 | ✔ |
1.00 | ±0.100 | ✔ |
1.00 | ±0.025 | ✔ |
2.00 | ±0.200 | ✔ |
2.00 | ±0.100 | ✔ |
2.00 | ±0.025 | ✔ |
3.00 | ±0.200 | ✔ |
3.00 | ±0.100 | ✔ |
3.00 | ±0.025 | ✔ |
Custom thicknesses are available on request. | ||
The thicknesses marked with "✔" are also available within our 48-hour express service. |
Refractive index data |
||
---|---|---|
Refractive Index name |
Wavelength (nm) |
Refractive Index |
ni |
365.0 |
1.53627 |
nh |
404.7 |
1.53024 |
ng |
435.8 |
1.52668 |
nF' |
480.0 |
1.52283 |
nF |
486.1 |
1.52238 |
ne |
546.1 |
1.51872 |
nd |
587.6 |
1.51680 |
nD |
589.3 |
1.51673 |
n632,8 |
632.8 |
1.51509 |
nC |
643.8 |
1.51472 |
nc |
656.3 |
1.51432 |
nr |
706.5 |
1.51289 |
ns |
852.1 |
1.50980 |
nt |
1014.0 |
1.50731 |
Additional detailed optical specifications about the SCHOTT N-BK7 glass material are available on request.
All given details and specifications are mean reference values and are not guaranteed. Also, please consider our "Notes on technical specifications".
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Last update: May 21, 2024