K-FK5 by Sumita

Standard Rare 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) 1.48749
Abbe Number (Vd) 70.4
Dispersion Formula Schott
Wavelength Range 0.36 — 1.55 µm
$$n(\lambda) = \sqrt{2.1892 - 0.00976422\,\lambda^2 + 0.00869174\,\lambda^{-2} + 0.000236466\,\lambda^{-4} - 1.77 \times 10^{-5}\,\lambda^{-6} + 9.69896 \times 10^{-7}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 8.8
TCE 100/300°C (10-6/K) 9.8
Thermal Conductivity (W/mK)
Heat Capacity (J/gK)
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-7.46 \times 10^{-6} + 2(1.15 \times 10^{-8})\,\Delta T + 3(-2.45 \times 10^{-10})\,\Delta T^2 + \frac{3.01 \times 10^{-7} + 2(2.4 \times 10^{-9})\,\Delta T}{\lambda - 0.169}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 2.45
Relative Cost
Mechanical Properties
Young's Modulus (GPa)
Poisson's Ratio
Knoop Hardness (kgf/mm²)
Chemical Resistance
Climatic Resistance 1
Stain Resistance
Acid Resistance 5
Alkali Resistance
Phosphate Resistance
Similar Glasses (Other Manufacturers)
Glass Manufacturer nd Vd
FK5 Schott 1.48749 70.405771
N-FK5 Schott 1.48749 70.41
FC5 Hoya 1.48749 70.44
H-QK3LGTI CDGM 1.48749 70.440487
D-QK3L CDGM 1.48749 70.440487
H-QK3L CDGM 1.48749 70.440487
S-FSL5Y Ohara 1.48749 70.354425
FK5HTi Schott 1.48748 70.47
D-QK3L-25 CDGM 1.48687 70.417086
A87-70 Corning 1.487248 70.500557
Similar Glasses (Sumita)
Glass Manufacturer nd Vd
FK5 Sumita 1.48749 70.4
K-PG325(M) Sumita 1.50506 70.4
K-PG325 Sumita 1.5067 70.5
BK10 Sumita 1.49782 67.0
K-PMK30(M) Sumita 1.52002 70.2
BK4 Sumita 1.50048 66.0
K-PMK30 Sumita 1.525 70.4
BK3 Sumita 1.49831 65.1
BK7 Sumita 1.51633 64.1
K-BK7 Sumita 1.51633 64.1
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