IRG 22

IRG 22

IRG 22 has excellent transmission in the SWIR, MWIR, & LWIR and has the best transmission of the IRG series in the NIR band with transmission beginning as low as 0.7 μm.

With physical properties such as low dn/dT and low dispersion enables the optical engineers to design color corrected optical systems without thermal defocusing.

Furthermore, IRG 22 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 Ge33As12Se55
Density 4.41 g/cm3
Thermal Expansion (20°C-100°C) 12.5·10-6/K
Transition Temperature 368°C
Thermal Change dn/dT (at 1 µm) 94.7·10-6/K
Thermal Change dn/dT (at 5 µm) 67.6·10-6/K
Thermal Change dn/dT (at 10 µm) 67.1·10-6/K
Refractive Index (n at 10 µm) 2.4968
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]
0.8 52.2 87.8 0.650
1.0 91.4 98.2 0.090
1.5 96.7 99.3 0.034
2.0 97.5 99.5 0.026
2.5 97.5 99.5 0.025
3.0 98.3 99.7 0.017
3.5 98.5 99.7 0.015
4.0 98.7 99.7 0.013
4.5 96.3 99.3 0.037
5.0 97.0 99.4 0.031
5.5 99.5 99.9 0.005
6.0 99.7 99.9 0.003
6.5 99.7 99.9 0.003
7.0 99.7 99.9 0.003
7.5 99.2 99.8 0.008
8.0 95.2 99.0 0.049
Wavelength
[µm]
Transmission
(10 mm)
Transmission
(2 mm)
Extinction
[cm-1]
8.5 98.5 99.7 0.015
9.0 98.8 99.8 0.012
9.5 98.7 99.7 0.013
10.0 98.8 99.8 0.012
10.5 97.8 99.6 0.022
11.0 93.7 98.7 0.065
11.5 78.0 95.2 0.248
12.0 40.2 83.4 0.910
12.5 15.8 69.2 1.844
13.0 16.9 70.1 1.779
13.5 43.0 84.4 0.845
14.0 65.2 91.8 0.428
14.5 70.3 93.2 0.353
15.0 64.3 91.5 0.442
15.5 49.9 87.0 0.696
Constants of Dispersion Formulas
B1 2.4834
B2 2.8203
B3 0.9773
C1 0.0000
C2 0.1352
C3 1,420.7000
D0 6.41·10-5
E0 1.68·10-7
λTK 9.96·10-1
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
1.0 2.5971 94.8
1.5 2.5462 69.1
2.0 2.5299 68.4
3.0 2.5182 68.0
4.0 2.5134 67.8
5.0 2.5104 67.7
6.0 2.5079 67.6
7.0 2.5054 67.5
8.0 2.5028 67.4
9.0 2.5000 67.3
10.0 2.4968 67.1
11.0 2.4933 67.0
12.0 2.4893 66.9
Wavelength
[µm]
Thermal Change
[dn/dt]
1 µm 94.7·10-6/K
5 µm 67.6·10-6/K
10 µm 67.1·10-6/K