IRG 27

IRG 27

IRG 27 exhibits excellent transmission through the short and mid-wave IR (SWIR-MWIR). The germanium-free composition offers various advantages, including a near zero dn/dT starting at 1.5 μm that continues through the MWIR and into the LWIR.

IRG 27 displays low dispersion for SWIR and MWIR applications and can be used as a flint material in achromatic doublets for multi-band IR applications.

The glass can be processed by conventional grinding and polishing methods, as well single point diamond turning, and molding. Based on similar thermal and mechanical characteristics to IRG 26, IRG 27 will process in a similar manner.

IR characteristics
Composition As2S3
Density 3.20 g/cm3
Thermal Expansion (20°C-100°C) 22.5·10-6/K
Transition Temperature 197°C
Thermal Change dn/dT (at 1 µm) 15.6·10-6/K
Thermal Change dn/dT (at 5 µm) -3.2·10-6/K
Thermal Change dn/dT (at 10 µm) -3.7·10-6/K
Refractive Index (n at 10 µm) 2.3873
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]
0.6 5.8 56.5 2.853
0.7 93.3 98.6 0.070
0.8 95.7 99.1 0.044
1.0 97.2 99.4 0.028
1.5 98.7 99.7 0.013
2.0 99.0 99.8 0.010
2.5 99.1 99.8 0.009
3.0 98.5 99.7 0.015
3.5 98.9 99.8 0.011
4.0 87.1 97.3 0.138
4.5 99.2 99.8 0.008
5.0 99.5 99.9 0.005
5.5 99.5 99.9 0.005
6.0 99.2 99.8 0.008
Wavelength
[µm]
Transmission
(10 mm)
Transmission
(2 mm)
Extinction
[cm-1]
6.5 99.0 99.8 0.010
7.0 97.8 99.5 0.023
7.5 96.5 99.3 0.036
8.0 96.5 99.3 0.035
8.5 91.0 98.1 0.094
9.0 69.3 92.9 0.367
9.5 46.8 85.9 0.760
10.0 38.8 82.8 0.946
10.5 44.9 85.2 0.801
11.0 43.9 84.8 0.822
11.5 28.2 77.7 1.264
12.0 11.8 65.2 2.137
12.5 1.6 43.5 4.158
12.7 0.1 24.5 7.026
Constants of Dispersion Formulas
B1 1.4005
B2 3.4429
B3 1.0394
C1 0.0000
C2 0.0871
C3 805.5000
D0 -3.89·10-6
E0 1.77·10-5
λTK 2.46·10-1
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
0.6 2.6347 62.2
0.7 2.5665 40.6
0.8 2.5268 28.4
0.8 2.5014 20.7
0.9 2.4841 15.6
1.0 2.4452 4.3
1.5 2.4320 0.6
2.0 2.4257 -1.0
3.0 2.4218 -1.9
4.0 2.4169 -2.8
5.0 2.4129 -3.2
6.0 2.4090 -3.4
7.0 2.4046 -3.5
8.0 2.3997 -3.6
9.0 2.3939 -3.6
10.0 2.3873 -3.7
11.0 2.3795 -3.7
12.0 2.3705 -3.7
Wavelength
[µm]
Thermal Change
[dn/dt]
1 µm 15.6·10-6/K
5 µm -3.2·10-6/K
10 µm -3.7·10-6/K