K-GFK68(M) by Sumita

Preferred Very Common 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: 0.270–2.000 µm
Optical Properties
Refractive Index (nd) 1.58998
Abbe Number (Vd) 68.3
Dispersion Formula Schott
Wavelength Range 0.36 — 1.55 µm
$$n(\lambda) = \sqrt{2.49212 - 0.00592524\,\lambda^2 + 0.0125413\,\lambda^{-2} + 0.000203793\,\lambda^{-4} - 3.77982 \times 10^{-6}\,\lambda^{-6} + 2.58299 \times 10^{-7}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 12.9
TCE 100/300°C (10-6/K) 15.2
Thermal Conductivity (W/mK)
Heat Capacity (J/gK)
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.36 \times 10^{-5} + 2(2.85 \times 10^{-9})\,\Delta T + 3(4.82 \times 10^{-11})\,\Delta T^2 + \frac{4.01 \times 10^{-7} + 2(2.74 \times 10^{-10})\,\Delta T}{\lambda - 0.183}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 4.51
Relative Cost
Mechanical Properties
Young's Modulus (GPa)
Poisson's Ratio
Knoop Hardness (kgf/mm²)
Chemical Resistance
Climatic Resistance 1
Stain Resistance
Acid Resistance 1
Alkali Resistance
Phosphate Resistance
Similar Glasses (Other Manufacturers)
Glass Manufacturer nd Vd
D-ZPK5-25 CDGM 1.59216 68.281511
N-PSK57 Schott 1.5924 68.398667
D-ZPK5 CDGM 1.5928 68.342024
H-ZPK5 CDGM 1.5928 68.342024
FCD505 Hoya 1.59282 68.62
FCD515 Hoya 1.59282 68.62
S-FPM2 Ohara 1.59522 67.735723
H-ZPK3 CDGM 1.59349 67.285372
D-ZPK3 CDGM 1.59419 67.295385
D-ZPK3-25 CDGM 1.59327 67.22642
Similar Glasses (Sumita)
Glass Manufacturer nd Vd
K-GFK68 Sumita 1.5924 68.3
GFK68 Sumita 1.5924 68.3
K-PSK400(M) Sumita 1.59179 67.7
K-PSK400 Sumita 1.595 67.8
K-PSK300 Sumita 1.5995 65.6
K-PSK300(M) Sumita 1.5969 65.3
GFK70 Sumita 1.56907 71.3
K-GFK70 Sumita 1.56907 71.3
K-PMK155 Sumita 1.5582 68.2
K-GFK70(M) Sumita 1.56627 71.3
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