K-LaFK55(M) by Sumita

Standard Medium Environmentally Friendly

K-LaFK55(M) by Sumita is a standard optical glass with a medium melt frequency. It transmits from 0.27 to 2.00 µm with an nd of 1.68875 and a Vd of 55.8. It has medium thermal expansion (CTE of 7.3×10⁻⁶/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: 0.270–2.000 µm
Optical Properties
Refractive Index (nd) 1.68875
Abbe Number (Vd) 55.8
Dispersion Formula Schott
Wavelength Range 0.36 — 1.55 µm
$$n(\lambda) = \sqrt{2.80081 - 0.0131887\,\lambda^2 + 0.0180963\,\lambda^{-2} + 0.000408528\,\lambda^{-4} - 1.28551 \times 10^{-5}\,\lambda^{-6} + 1.05131 \times 10^{-6}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 7.3
TCE 100/300°C (10-6/K) 9.1
Thermal Conductivity (W/mK) —
Heat Capacity (J/gK) —
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.43 \times 10^{-6} + 2(1.08 \times 10^{-8})\,\Delta T + 3(-8.1 \times 10^{-11})\,\Delta T^2 + \frac{5.36 \times 10^{-7} + 2(6.73 \times 10^{-10})\,\Delta T}{\lambda - 0.111}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 4.34
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
LAL9 Ohara 1.691002 54.84322
S-LAL9 Ohara 1.691002 54.822578
H-LAK59A CDGM 1.691 54.815309
C90-55 Corning 1.691008 54.793839
LAK9G15 Schott 1.69064 54.76
S-LAL14 Ohara 1.696797 55.532241
LAL14 Ohara 1.696796 55.528037
H-LAK51A CDGM 1.6968 55.526357
N-LAK9 Schott 1.691 54.71
LAK9 Schott 1.691002 54.708408
Similar Glasses (Sumita)
Glass Manufacturer nd Vd Compare
LAFK55 Sumita 1.694 56.3
K-LaFK55 Sumita 1.694 56.3
K-LaK9 Sumita 1.691 54.8
LAK9 Sumita 1.691 54.8
LAK14 Sumita 1.6968 55.6
K-LaK14 Sumita 1.6968 55.6
K-LaK12 Sumita 1.6779 55.5
LAK12 Sumita 1.6779 55.5
LAK13 Sumita 1.6935 53.4
K-LaFK58(M) Sumita 1.69097 58.4
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