Chalcogenide glass sphere/asphere (IR glass)

CPG is working with a lot of material vendor in chalcogenide glass: Schott, Virton, Umicore, CDGM, NHG etc.

IR glass is a wonderful material can be: polished, molded, diamond turned etc. The key control to provide reliable components with this material is the knowledge in production process control and the coating process.

Below is the excellent introduction of the materials:

Reliable solutions for the infrared?industry

Infrared glasses (IRG) offer excellent transmission in the shortwave IR (SWIR), midwave IR (MWIR),?and longwave (LWIR) range. Physical properties such as low dn/dT and low dispersion enable optical designers to engineer color-correcting optical systems without thermal defocusing. The IRG family of chalcogenide glasses is optimized for pairing with the family of IR glasses and other IR materials to support cost-effective and high-performance optical designs. These glasses encompass the common IR transmission bands 3 - 5 μm and 8 - 12 μm, but can transmit as low as 0.7 μm. Furthermore, the IR glass series offered by SCHOTT can be processed using conventional grinding and polishing techniques, single point diamond turning or molding to support low- to high-volume component-level 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
Material Properties	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: