K-LaK9 by Sumita

Standard Rare Environmentally Friendly

K-LaK9 by Sumita is a standard optical glass with a rare melt frequency. It transmits from 0.31 to 2.00 µm with an nd of 1.691 and a Vd of 54.8. It has medium thermal expansion (CTE of 7.2×10⁻⁶/K) and average chemical resistance.

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) 1.691
Abbe Number (Vd) 54.8
Dispersion Formula Schott
Wavelength Range 0.36 — 1.55 µm
$$n(\lambda) = \sqrt{2.80651 - 0.0120847\,\lambda^2 + 0.0185097\,\lambda^{-2} + 0.000456897\,\lambda^{-4} - 1.5276 \times 10^{-5}\,\lambda^{-6} + 1.00185 \times 10^{-6}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 7.2
TCE 100/300°C (10-6/K) 8.6
Thermal Conductivity (W/mK) —
Heat Capacity (J/gK) —
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-3.41 \times 10^{-6} + 2(2.03 \times 10^{-8})\,\Delta T + 3(-1.26 \times 10^{-10})\,\Delta T^2 + \frac{4.75 \times 10^{-7} + 2(9.33 \times 10^{-11})\,\Delta T}{\lambda - 0.17}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 4.06
Relative Cost —
Mechanical Properties
Young's Modulus (GPa) —
Poisson's Ratio —
Knoop Hardness (kgf/mm²) —
Chemical Resistance
Climatic Resistance 1
Stain Resistance —
Acid Resistance 4
Alkali Resistance —
Phosphate Resistance —
Similar Glasses (Other Manufacturers)
Glass Manufacturer nd Vd Compare
C90-55 Corning 1.691008 54.793839
H-LAK59A CDGM 1.691 54.815309
S-LAL9 Ohara 1.691002 54.822578
LAL9 Ohara 1.691002 54.84322
LAK9G15 Schott 1.69064 54.76
N-LAK9 Schott 1.691 54.71
LAK9 Schott 1.691002 54.708408
LAC9 Hoya 1.691 54.7
H-LAK2A CDGM 1.69211 54.539198
N-LAK14 Schott 1.6968 55.41
Similar Glasses (Sumita)
Glass Manufacturer nd Vd Compare
LAK9 Sumita 1.691 54.8
K-LaFK55(M) Sumita 1.68875 55.8
LAK14 Sumita 1.6968 55.6
K-LaK14 Sumita 1.6968 55.6
LAK13 Sumita 1.6935 53.4
LAFK55 Sumita 1.694 56.3
K-LaFK55 Sumita 1.694 56.3
K-VC80 Sumita 1.69384 53.1
K-VC80(M) Sumita 1.68983 52.9
K-LaK12 Sumita 1.6779 55.5
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