BAK4 by Sumita

Obsolete Very Rare Environmentally Dangerous

BAK4 by Sumita is an obsolete optical glass with a very rare melt frequency. It transmits from 0.31 to 2.00 µm with an nd of 1.56883 and a Vd of 56.0. It has excellent chemical resistance and dangerous environmental properties.

Refractive Index vs Wavelength
Refractive Index Calculator
Valid range: 0.27–2.0 µm
dn/dλ vs Wavelength
dn/dλ Calculator
Valid range: 0.27–2.0 µm
Abbe Number Calculator
Transmission vs Wavelength
Transmission Calculator
Valid wavelength range: 0.310–2.000 µm
Optical Properties
Refractive Index (nd) 1.56883
Abbe Number (Vd) 56.0
Dispersion Formula Schott
Wavelength Range 0.27 — 2.0 µm
$$n(\lambda) = \sqrt{2.42201 - 0.0093683\,\lambda^2 + 0.0137364\,\lambda^{-2} + 0.000345416\,\lambda^{-4} - 1.21259 \times 10^{-5}\,\lambda^{-6} + 9.23699 \times 10^{-7}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) —
TCE 100/300°C (10-6/K) 8.5
Thermal Conductivity (W/mK) —
Heat Capacity (J/gK) —
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[0 + 2(0)\,\Delta T + 3(0)\,\Delta T^2 + \frac{0 + 2(0)\,\Delta T}{\lambda - 0}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$
Physical Properties
Density (g/cm³) 3.11
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
N-BAK4HT Schott 1.56883 55.98
N-BAK4 Schott 1.56883 55.98
BAC4 Hoya 1.56883 56.04
H-BAK7 CDGM 1.56883 56.041308
H-BAK7GT CDGM 1.56883 56.041308
B69-56 Corning 1.568797 56.044859
H-BAK7A CDGM 1.568828 56.127804
BAK4 Schott 1.56883 56.130661
BAL14 Ohara 1.568832 56.339266
S-BAL14 Ohara 1.568832 56.363897
Similar Glasses (Sumita)
Glass Manufacturer nd Vd Compare
BAK1 Sumita 1.5725 57.5
K-CSK158(M) Sumita 1.58157 56.7
K-CSK158 Sumita 1.584 56.9
BPG2 Sumita 1.5592 53.9
K-BPG2 Sumita 1.5592 53.9
BALF3 Sumita 1.57135 53.0
K-SKLD200(M) Sumita 1.58355 58.8
BALF5 Sumita 1.54739 53.6
SK12 Sumita 1.58313 59.3
K-CSK120(M) Sumita 1.58445 59.2
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