Chalcogenide spherical/aspherical glass (IR glass)

CPG collaborates with lots of vendors in chalcogenide glass, including Schott, Virton, Umicore, CDGM, and NHG.

IR glass is an exceptional material that can be polished, molded, or diamond turned. The key to producing reliable components from this material lies in our expertise in production process control and coating techniques.

Below is an excellent introduction to these materials.

Reliable solutions for the infrared industry

Infrared glasses (IRG) provide outstanding transmission across the shortwave IR (SWIR), midwave IR (MWIR), and longwave IR (LWIR) ranges. With key properties like low dn/dT and minimal dispersion, they allow optical designers to create color-corrected systems that resist thermal defocusing. The IRG series of chalcogenide glasses is specifically optimized for integration with other IR glasses and materials, offering a cost-effective solution for high-performance optical designs. These glasses cover common IR transmission bands at 3 - 5 μm and 8 - 12 μm and can transmit wavelengths as low as 0.7 μm. Additionally, SCHOTT’s IR glass series can be processed via conventional grinding and polishing, single-point diamond turning, or molding, making it suitable for low- to high-volume component manufacturing.

Advantages

  • Low dn/dT and low dispersion
  • Excellent transmission in SWIR, MWIR and LWIR
  • Excellent transmission in SWIR, MWIR and LWIR
  • Effective production from prototypes to mass volumes
  • Superior quality and repeatable performance proven by internal measurements and process controls of batch material
  • Effective performance for color correcting optical systems and athermal imaging designs

Technical Details

IR Transmission

Material Properties IRG 22 - IRG 27

Material Properties Infrared Chalcogenide Glasses
IRG 22 IRG 24 IRG 25 IRG 26 IRG 27
Composition Ge33As12Se55 Ge10As40Se50 Ge28Sb12Se60 As40Se60 As40Se60
Density 4.41 g/cm3 4.47 g/cm3 4.66 g/cm3 4.63 g/cm3 3.20 g/cm3
Thermal expansion
(20 – 100°C)		 12.5 · 10–6/K 20.0 · 10–6/K 14.0 · 10–6/K 21.4 · 10–6/K 22.5 · 10–6/K
Transition temperature 368 °C 225 °C 285 °C 185 °C 197 °C
Thermal change dn/dT* 94.8 · 10–6/K
(1 μm)		 46.0 · 10–6/K
(1 μm)		 79.2 · 10–6/K
(1 μm)		 76.2 · 10–6/K
(1 μm)		 15.6 · 10–6/K
(1 μm)
67.7 · 10–6/K
(5 μm)		 21.15 · 10–6/K
(5 μm)		 62.0 · 10–6/K
(5 μm)		 33.4 · 10–6/K
(5 μm)		 -3.2 · 10–6/K
(5 μm)
67.1 · 10–6/K
(10 μm)		 20.3 · 10–6/K
(10 μm)		 61.1 · 10–6/K
(10 μm)		 32.2 · 10–6/K
(10.6 μm)		 -3.7 · 10–6/K
(10.6 μm)
Refractive index 2.5971
(1 μm)		 2.7249
(1 μm)		 2.7284
(1 μm)		 2.9316
(1 μm)		 2.4841
(1 μm)
2.5104
(5 μm)		 2.6192
(5 μm)		 2.6183
(5 μm)		 2.7909
(5 μm)		 2.4129
(5 μm)
2.4968
(10 μm)		 2.6090
(10 μm)		 2.6030
(10 μm)		 2.7781
(10 μm)		 2.3842
(10 μm)

*Please contact us or schott if you would like more information or have any questions.

Data sheet of Schott: