IRG 25

IRG 25

IRG 25 has excellent transmission in the SWIR, MWIR, & LWIR. Physical properties such as low dn/dT and low dispersion enable optical engineers to design color corrected optical systems without thermal defocusing.

Furthermore, IRG 25 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 Ge28Sb12Se60
Density 4.66 g/cm3
Thermal Expansion (20°C-100°C) 14.0·10-6/K
Transition Temperature 285°C
Thermal Change dn/dT (at 1 µm) 79.2·10;-6/K
Thermal Change dn/dT (at 5 µm) 62.0·10;-6/K
Thermal Change dn/dT (at 10 µm) 61.1·10;-6/K
Refractive Index (n at 10 µm) 2.6030
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 2.7574
B2 3.0990
B3 1.6660
C1 0.0000
C2 0.1596
C3 2,045.5000
D0 5.50·10-5
E0 1.21·10-5
λTK 7.59·10-5
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 2.7811 0.0
1.0 2.7284 79.2
1.5 2.6629 69.0
2.0 2.6423 65.7
3.0 2.6277 63.3
4.0 2.6219 62.4
5.0 2.6183 62.0
6.0 2.6154 61.8
7.0 2.6126 61.6
8.0 2.6097 61.4
9.0 2.6065 61.3
10.0 2.6030 61.1
11.0 2.5992 61.0
12.0 2.5949 60.8
Wavelength
[µm]
Thermal Change
[dn/dt]
1 µm 79.2·10;-6/K
5 µm 62.0·10;-6/K
10 µm 61.1·10;-6/K