K-GFK70 by Sumita

Preferred Very Common Precision Molding Environmentally Friendly

K-GFK70 by Sumita is a preferred optical glass with a very common melt frequency. It transmits from 0.27 to 2.00 µm with an nd of 1.56907 and a Vd of 71.3. It has high thermal expansion (CTE of 13.2×10⁻⁶/K), excellent chemical resistance, and precision molding compatibility.

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) 1.56907
Abbe Number (Vd) 71.3
Dispersion Formula Schott
Wavelength Range 0.36 — 1.55 µm
$$n(\lambda) = \sqrt{2.42939 - 0.00575911\,\lambda^2 + 0.011512\,\lambda^{-2} + 0.000132492\,\lambda^{-4} + 7.325 \times 10^{-6}\,\lambda^{-6} - 5.71954 \times 10^{-7}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 13.2
TCE 100/300°C (10-6/K) 15.6
Thermal Conductivity (W/mK) —
Heat Capacity (J/gK) —
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.47 \times 10^{-5} + 2(-1.68 \times 10^{-9})\,\Delta T + 3(-2.49 \times 10^{-11})\,\Delta T^2 + \frac{3.77 \times 10^{-7} + 2(3.45 \times 10^{-10})\,\Delta T}{\lambda - 0.178}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 4.48
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 Compare
D-ZPK7 CDGM 1.56907 71.304254
H-ZPK7 CDGM 1.56907 71.304254
N-PSK58 Schott 1.56907 71.205585
D-ZPK7-25 CDGM 1.56854 71.235367
FCD615 Hoya 1.57144 71.61
B58-72 Corning 1.558086 71.998499
FCD500 Hoya 1.55397 71.76
MC-FCD500-20 Hoya 1.55352 71.72
MP-FCD500-20 Hoya 1.55352 71.72
M-FCD500 Hoya 1.55332 71.69
Similar Glasses (Sumita)
Glass Manufacturer nd Vd Compare
GFK70 Sumita 1.56907 71.3
K-GFK70(M) Sumita 1.56627 71.3
K-PSK500 Sumita 1.55215 72.0
K-PSK500(M) Sumita 1.55 71.9
K-PMK155 Sumita 1.5582 68.2
K-PMK155(M) Sumita 1.55471 68.0
K-GFK68(M) Sumita 1.58998 68.3
GFK68 Sumita 1.5924 68.3
K-GFK68 Sumita 1.5924 68.3
K-PSK400(M) Sumita 1.59179 67.7
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