IRG 26

IRG 26

IRG 26 has excellent transmission in the SWIR, MWIR, & LWIR. The Chalcogenide composition of IRG 26 does not contain Germanium (Ge) and therefore offers the broadest transmission of the IR glass series with minimal absorption at 12.5 μm.

Physical properties such as low dn/dT and low dispersion enable optical engineers to design color corrected optical systems without thermal defocusing.

Furthermore, IRG 26 can be processed by conventional grinding and polishing, single point diamond turning, or molding to support low to high volume component level fabrication.

IR characteristics
Composition As40Se60
Density 4.63 g/cm3
Thermal Expansion (20°C-100°C) 21.4·10-6/K
Transition Temperature 185°C
Thermal Change dn/dT (at 1 µm) 76.1·10;-6/K
Thermal Change dn/dT (at 5 µm) 33.4·10;-6/K
Thermal Change dn/dT (at 10 µm) 32.1·10;-6/K
Refractive Index (n at 10 µm) 2.7781
Surface quality 60/40 polished both sides
Surface flatness ≤ 5 waves P-V per surface at 632.8nm
Edge Worked Saftety bevel
Glass type
Article DIA
T
Weight
Wavelength
[µm]
Transmission
(10 mm)
Transmission
(2 mm)
Extinction
[cm-1]
1.0 81.6 96.0 0.203
1.5 95.7 99.1 0.044
2.0 96.2 99.2 0.039
2.5 96.3 99.2 0.038
3.0 96.5 99.3 0.036
3.5 97.5 99.5 0.025
4.0 98.0 99.6 0.020
4.5 95.6 99.1 0.045
5.0 95.6 99.1 0.045
5.5 98.8 99.8 0.012
6.0 99.0 99.8 0.010
6.5 98.9 99.8 0.011
7.0 99.1 99.8 0.009
7.5 98.7 99.7 0.013
8.0 96.1 99.2 0.040
Wavelength
[µm]
Transmission
(10 mm)
Transmission
(2 mm)
Extinction
[cm-1]
8.5 98.1 99.6 0.019
9.0 97.9 99.6 0.021
9.5 98.0 99.6 0.020
10.0 98.2 99.6 0.018
10.5 96.9 99.4 0.031
11.0 93.8 98.7 0.064
11.5 85.0 96.8 0.163
12.0 60.1 90.3 0.509
12.5 31.1 79.2 1.167
13.0 31.1 79.2 1.167
13.5 52.0 87.7 0.654
14.0 69.7 93.0 0.361
14.5 71.8 93.6 0.332
15.0 63.1 91.2 0.461
15.5 47.2 86.0 0.752
Constants of Dispersion Formulas
B1 3.1934
B2 3.5854
B3 2.2337
C1 0.0000
C2 0.1852
C3 3,398.0804
D0 2.63·10-5
E0 2.93·10-5
λTK 3.15·10-1
Calculation Formula: Refractive index as a function of wavelength and temperature
Wavelength
[µm]
Refractive Index
(@ 22 °C)
Δn abs/ΔT [10–6/K]
22 °C
0.8 3.0026 0.0
1.0 2.9316 76.2
1.5 2.8460 49.8
2.0 2.8197 41.7
3.0 2.8015 36.2
4.0 2.7947 34.3
5.0 2.7909 33.4
6.0 2.7882 33.0
7.0 2.7857 32.7
8.0 2.7833 32.5
9.0 2.7808 32.3
10.0 2.7781 32.2
11.0 2.7753 32.1
12.0 2.7722 32.0
Wavelength
[µm]
Thermal Change
[dn/dt]
1 µm 76.1·10;-6/K
5 µm 33.4·10;-6/K
10 µm 32.1·10;-6/K