Optical Glass (N-BK7 and others)
DownloadN-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
Transmission Range
350nm to 2.5 μm
Refractive Index
1.51680 @ 587.5618 nm (Yellow Helium Line)
Reflection Loss
8.1% at 587.5618 μm (2 surfaces)
Absorption Coefficient
n/a
Reststrahlen Peak
n/a
dn/dT
See Schott Table
dn/dμ = 0
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
Youngs Modulus (E)
82 GPa
Shear Modulus (G)
n/a
Bulk Modulus (K)
34 GPa
Elastic Coefficients
n/a
Apparent Elastic Limit
63.5 MPa (9206psi)
Poisson Ratio
0.206
Solubility
Insoluble in water
Molecular Weight
n/a
Class/Structure
Amorphous glass
