K8 glass
K8 glass is a type of high-quality borosilicate crown optical glass that is primarily used in precision optical components like lenses and windows. It is the Russian equivalent of the more widely known Schott BK7 glass. K8 glass is known for its excellent optical clarity and transmission in the visible and near-infrared spectrum, high mechanical and chemical resistance, and low levels of internal defects like bubbles and inclusions.
- Optical properties: It has a refractive index of about 1.5168 and a dispersion of 64.20. It offers high transmission from the ultraviolet (UV) to the near-infrared (approx. 350 nm to 2.0 µm).
- Physical properties: It is a hard and durable glass that is resistant to scratches and other physical or chemical impacts.
- Applications: It is widely used in various optical instruments and components, including high-precision lenses, prisms, and windows.
- Manufacturing: It is produced with a low count of bubbles and inclusions, making it suitable for high-precision applications.
- Surface treatments: K8 optical windows can be supplied without coatings or with various anti-reflective coatings for specific wavelength ranges
Optical characteristics K8
| Refractive Index at ne | 1.51872 |
|---|---|
|
Refractive Index, at nF |
1.52283 |
|
Thermal Coefficient of Refractive index at |=0.546 microns, °C-1 for 0,+20°C |
2.8 . 10-6 |
|
Transmission Range microns (thickness 10MM) |
0.35,2 |
|
Transmittance ti (l) vs. wavelength l BK7 |
|
| Internal Transmittance ti (l) vs. wavelenght l | |
|---|---|
|
l,MKM |
ti(l) |
|
0.310 |
0.59 |
|
0.320 |
081 |
|
0.350 |
0.986 |
|
0.365 |
0.994 |
|
0.370 |
0.995 |
|
0.380 |
0.996 |
|
0.390 |
0.998 |
|
0.400 |
0.998 |
|
0.420 |
0.998 |
|
0.460 |
0.999 |
|
0.500 |
0.999 |
|
0.700 |
0.999 |
|
1.060 |
0.999 |
|
1.530 |
0.997 |
|
1.970 |
0.968 |
|
2.325 |
0.89 |
|
Refractive Index n vs. wavelength l |
|
|---|---|
|
l,MKM |
no/ne |
|
0.365 |
1.53626 |
|
0.4047 |
1.53024 |
|
0.4358 |
1.52669 |
|
0.4800 |
1.52283 |
|
0.4861 |
1.52238 |
|
0.5461 |
1.51872 |
|
0.5876 |
1.51680 |
|
0.5893 |
1.51673 |
|
0.6328 |
1.51509 |
|
0.6438 |
1.51472 |
|
0.6563 |
1.51432 |
|
0.7065 |
1.51289 |
|
0.8521 |
1.50981 |
|
1.0140 |
1.50731 |
|
1.0600 |
1.50669 |
|
1.5296 |
1.50094 |
|
1.9700 |
1.49500 |
|
2.3254 |
1.48929 |
Thermo-physical characteristics K8
| Thermal Linear Expansion at, °C-1 for -30,+70°C | 7.1 . 10-6 |
|---|---|
|
Thermal Conductivity W/(m .°C) at 20 °C |
1.114 |
|
Specific Heat Capacity, J/(kg .°C) |
858.0 |
|
Melting Point, °C |
559 |
Mechanical characteristics K8
| Density, g/cm3 at 20 °C | 2.51 |
|---|---|
|
Poisson Ratio |
0.206 |
|
Young Modulus (E), Pa |
8.1 . 1010 |