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Optical Glass (N-BK7 and others)
N-BK7 is a Schott designation for the most common Borosilicate Crown glass used for a wide variety of visible applications. The basic data here is given for N-BK7. There is a huge range of glasses available for which we hold data and some stock
Windows
Prisms & ATR
| Transmission Range | 350 nm to 2.5 μm |
| Refractive Index | 1.51680 @ 587.5618 nm (Yellow Helium Line) |
| Reflection Loss | 8.1% at 587.5618 nm (2 surfaces) |
| Absorption Coefficient | n/a |
| Reststrahlen Peak | n/a |
| dn/dT | See Schott Table |
| dn/dμ | n/a |
| Density | 2.51 g/cc |
| Melting Point | 557°C (transformation temperature) |
| Thermal Conductivity | 1.114 W m-1 K-1 |
| Thermal Expansion | 7.1 x 10-6/°C |
| Hardness | Knoop 610 |
| Specific Heat Capacity | 858 J Kg-1 K-1 |
| Dielectric Constant | n/a |
| Young's Modulus (E) | 82 GPa |
| Shear Modulus (G) | n/a |
| Bulk Modulus (K) | 34 GPa |
| Elastic Coefficients | n/a |
| Apparent Elastic Limit | 63.5 MPa (9206 psi) |
| Poisson Ratio | 0.206 |
| Solubility | Insoluble in water |
| Molecular Weight | n/a |
| Class/Structure | Amorphous glass |