K-SK7 by Sumita

Standard Rare Environmentally Friendly

K-SK7 by Sumita is a standard optical glass with a rare melt frequency. It transmits from 0.29 to 2.00 µm with an nd of 1.60729 and a Vd of 59.5. It has medium thermal expansion (CTE of 7.1×10⁻⁶/K) and below 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: 0.290–2.000 µm
Optical Properties
Refractive Index (nd) 1.60729
Abbe Number (Vd) 59.5
Dispersion Formula Schott
Wavelength Range 0.36 — 1.55 µm
$$n(\lambda) = \sqrt{2.54293 - 0.0103172\,\lambda^2 + 0.0143569\,\lambda^{-2} + 0.000314339\,\lambda^{-4} - 1.08243 \times 10^{-5}\,\lambda^{-6} + 6.81009 \times 10^{-7}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 7.1
TCE 100/300°C (10-6/K) 7.7
Thermal Conductivity (W/mK) —
Heat Capacity (J/gK) —
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[2.39 \times 10^{-7} + 2(1.74 \times 10^{-8})\,\Delta T + 3(-2.81 \times 10^{-10})\,\Delta T^2 + \frac{4.14 \times 10^{-7} + 2(1.06 \times 10^{-9})\,\Delta T}{\lambda - 0.188}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 3.5
Relative Cost —
Mechanical Properties
Young's Modulus (GPa) —
Poisson's Ratio —
Knoop Hardness (kgf/mm²) —
Chemical Resistance
Climatic Resistance 3
Stain Resistance —
Acid Resistance 5
Alkali Resistance —
Phosphate Resistance —
Similar Glasses (Other Manufacturers)
Glass Manufacturer nd Vd Compare
BACD7 Hoya 1.607292 59.474776
SK7 Schott 1.60729 59.459272
BSM7 Ohara 1.607291 59.375631
C09-59 Corning 1.608756 59.036803
SK3 Schott 1.60881 58.921505
BACD3 Hoya 1.608812 58.863994
H-ZK4 CDGM 1.60881 58.855991
BSM4 Ohara 1.612716 58.749129
S-BSM4 Ohara 1.612716 58.716945
N-SK4 Schott 1.61272 58.63
Similar Glasses (Sumita)
Glass Manufacturer nd Vd Compare
SK7 Sumita 1.60729 59.5
SK3 Sumita 1.60881 58.9
K-PSK200(M) Sumita 1.61083 58.9
K-PSK200 Sumita 1.61305 59.0
SK4 Sumita 1.61272 58.6
K-SK4 Sumita 1.61272 58.6
K-SK14 Sumita 1.60311 60.7
SK14 Sumita 1.60311 60.7
K-VC79 Sumita 1.61035 57.9
VC79 Sumita 1.6097 57.8
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