K-LaK12 by Sumita

Standard Medium Environmentally Friendly
Refractive Index vs Wavelength
Refractive Index Calculator
Valid range: 0.36–1.55 µm
dn/dλ vs Wavelength
dn/dλ Calculator
Valid range: 0.36–1.55 µm
Abbe Number Calculator
Transmission vs Wavelength
Transmission Calculator
Valid wavelength range: 0.310–2.000 µm
Optical Properties
Refractive Index (nd) 1.6779
Abbe Number (Vd) 55.5
Dispersion Formula Schott
Wavelength Range 0.36 — 1.55 µm
$$n(\lambda) = \sqrt{2.76444 - 0.0117852\,\lambda^2 + 0.0179572\,\lambda^{-2} + 0.000347331\,\lambda^{-4} + 3.64396 \times 10^{-6}\,\lambda^{-6} - 3.28638 \times 10^{-7}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 6.9
TCE 100/300°C (10-6/K) 8.1
Thermal Conductivity (W/mK)
Heat Capacity (J/gK)
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-3.52 \times 10^{-6} + 2(1.96 \times 10^{-8})\,\Delta T + 3(-6.9 \times 10^{-11})\,\Delta T^2 + \frac{5.11 \times 10^{-7} + 2(4.65 \times 10^{-10})\,\Delta T}{\lambda - 0.152}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 3.98
Relative Cost
Mechanical Properties
Young's Modulus (GPa)
Poisson's Ratio
Knoop Hardness (kgf/mm²)
Chemical Resistance
Climatic Resistance 1
Stain Resistance
Acid Resistance 3
Alkali Resistance
Phosphate Resistance
Similar Glasses (Other Manufacturers)
Glass Manufacturer nd Vd
H-LAK5A CDGM 1.6779 55.51497
LAC12 Hoya 1.6779 55.52
C78-56 Corning 1.678004 55.519168
S-LAL12Q Ohara 1.6779 55.346888
S-LAL12 Ohara 1.6779 55.341195
LAL12 Ohara 1.6779 55.337587
N-LAK12 Schott 1.6779 55.2
LAKN12 Schott 1.6779 55.199566
LAKL12 Schott 1.6779 54.92
D-LAK5 CDGM 1.6779 54.889665
Similar Glasses (Sumita)
Glass Manufacturer nd Vd
LAK12 Sumita 1.6779 55.5
K-VC78 Sumita 1.66955 55.4
VC78 Sumita 1.6691 55.4
K-LaFK55(M) Sumita 1.68875 55.8
K-VC78(M) Sumita 1.66624 55.1
LAK9 Sumita 1.691 54.8
K-LaK9 Sumita 1.691 54.8
K-LaKn4 Sumita 1.671 57.2
LAKN4 Sumita 1.671 57.2
LAKN9 Sumita 1.678 53.3
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