TAFD25 by Hoya

Special Very Rare Environmentally Dangerous

TAFD25 by Hoya is a special optical glass with a very rare melt frequency. It transmits from 0.36 to 2.50 µm with an nd of 1.90366 and a Vd of 31.32. It has medium thermal expansion (CTE of 7.0×10⁻⁶/K), excellent chemical resistance, and dangerous environmental properties.

Refractive Index vs Wavelength
Refractive Index Calculator
Valid range: 0.36501–1.5296 µm
dn/dλ vs Wavelength
dn/dλ Calculator
Valid range: 0.36501–1.5296 µm
Abbe Number Calculator
Transmission vs Wavelength
Transmission Calculator
Valid wavelength range: 0.360–2.500 µm
Optical Properties
Refractive Index (nd) 1.90366
Abbe Number (Vd) 31.32
Dispersion Formula Schott
Wavelength Range 0.36501 — 1.5296 µm
$$n(\lambda) = \sqrt{3.49055 - 0.0163258\,\lambda^2 + 0.0411463\,\lambda^{-2} + 0.00271691\,\lambda^{-4} - 0.000182605\,\lambda^{-6} + 2.06419 \times 10^{-5}\,\lambda^{-8}}$$
Thermal Properties
TCE -30/70°C (10-6/K) 7.0
TCE 100/300°C (10-6/K) 8.8
Thermal Conductivity (W/mK) —
Heat Capacity (J/gK) —
$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.77 \times 10^{-7} + 2(7.51 \times 10^{-9})\,\Delta T + 3(-2.95 \times 10^{-11})\,\Delta T^2 + \frac{1.02 \times 10^{-6} + 2(9.45 \times 10^{-10})\,\Delta T}{\lambda - 0.245}\right] \Delta T = T - T_0, \quad T_0 = 23\,°\text{C}$$
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 1
Acid Resistance 1
Alkali Resistance —
Phosphate Resistance —
Notes

Recommended glass type

Similar Glasses (Other Manufacturers)
Glass Manufacturer nd Vd Compare
N-LASF46A Schott 1.90366 31.32
N-LASF46B Schott 1.90366 31.32
H-ZLAF75A CDGM 1.90366 31.31497
S-LAH95 Ohara 1.903659 31.343065
H-ZLAF75C CDGM 1.90366 31.357126
H-ZLAF75B CDGM 1.90366 31.418411
L-LAH86 Ohara 1.902699 31.00532
LAH78 Ohara 1.901355 31.550244
N-LASF46 Schott 1.90138 31.64
SRMOO4 Generic Birefringent 1.908806 29.94765
Similar Glasses (Hoya)
Glass Manufacturer nd Vd Compare
TAFD25L Hoya 1.90366 31.32
TAFD20 Hoya 1.90315 29.835563
TAFD35L Hoya 1.91082 35.25
TAFD35 Hoya 1.91082 35.25
NBFD27 Hoya 1.9011 27.06
TAFD21 Hoya 1.9326 27.921009
TAFD31 Hoya 1.922501 35.946005
TAFD37A Hoya 1.90043 37.37
TAFD37 Hoya 1.90043 37.37
NBFD30 Hoya 1.85883 30.0
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