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Optical constants of SCHOTT - IRG
IRG 27

Wavelength: µm
 (0.6–12.7)  
 

Complex refractive index (n+ik)[ i ]


n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]

$$n^2-1=1.4005+\frac{3.4429λ^2}{λ^2-0.0871}+\frac{1.0394λ^2}{λ^2-805.5}$$

Conditions & Spec sheet

n_is_absolute: false
wavelength_is_vacuum: false
temperature: 20.0 °C
thermal_dispersion:
  - type: "Schott formula"
    coefficients: -3.89e-06 0 0 1.77e-05 0 6.04e-02
density: 3.20 g/cm3
thermal_expansion:
  - temperature_range: 20 100 °C
    coefficient: 22.5e-06 K-1
specific_heat: 0.482 J/(g·K)
thermal_conductivity:
  - temperature: 25 °C
    value: 0.33 W/(m·K)
transition_temperature: 197 °C
Knoop_hardness: 1.11 GPa
fracture_toughness: 0.285 MPa·m1/2
Youngs_modulus: 16.77 GPa

References

SCHOTT Infrared Chalcogenide Glasses - IRG 27 Product flyer (Version April 2017)

Data

[Expressions for n]   [CSV - comma separated]   [TXT - tab separated]   [Full database record]

INFO

Infrared glass

Chalcogenide glasses are a specialized class of optical materials made primarily from chalcogen elements like sulfur, selenium, and tellurium, combined with other elements such as arsenic, antimony, or gallium. These glasses are particularly noteworthy for their broad transmission range in the infrared (IR) spectrum, often extending from the near-infrared through to the mid- and far-infrared wavelengths. Unlike more common oxide-based glasses like fused silica, chalcogenide glasses are capable of transmitting IR light up to wavelengths of around 10–20 micrometers, making them ideal for applications like thermal imaging, IR spectroscopy, and fiber-optic communications in the IR range. They also offer other favorable optical and mechanical properties, including high refractive indices and lower dispersion. However, these glasses are typically more expensive to produce and may be sensitive to moisture or less chemically stable than their oxide-based counterparts. Nevertheless, the unique capabilities of chalcogenide glasses make them indispensable in specialized applications where IR transmission and performance are critical.

Infrared glass types/brands from different makers

  • AMTIR (an acronym for "Amorphous Material Transmitting Infrared Radiation"): Amorphous Materials Inc. (AMI)
  • IG: VITRON
  • IRG: SCHOTT
  • BD: LightPath
  • OPTIR: Rochester Precision Optics (RPO)

Cross-reference

Composition AMI VITRON SCHOTT LightPath RPO
Ge33As12Se55 AMTIR-1 IG 2 IRG 22 OPTIR-1*
Ge30Sb13Se32Te25 IG 3 IRG 23*
Ge10As40Se50 IG 4 IRG 24
Ge28Sb12Se60 AMTIR-3* IG 5 IRG 25 BD-2 OPTIR-3*
As40Se60 AMTIR-2 IG 6 IRG 26 BD6
As40S60 AMTIR-6 IRG 27
(*) Out of production

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Glass

Glass is a versatile, amorphous material that has been an essential component in optical technologies for centuries. Comprising mainly of silica along with various additives like soda, lime, or boron, glass can be engineered to exhibit a wide range of optical properties, such as refractive indices and dispersion characteristics. In the optical industry, specialized types of glass like crown, flint, and extra-low dispersion (ED) glasses are used for manufacturing lenses, prisms, and other optical elements. These glasses are precisely formulated to offer specific properties, such as low chromatic aberration or high light transmittance across different spectral ranges. Glass can also be coated with thin layers of materials like anti-reflective coatings to enhance its optical performance. More recently, advances in photonics and nanotechnology have led to the development of innovative glass types, such as photonic crystal and metamaterial glasses, which exhibit unique light-manipulating properties. It is crucial to note that the optical properties of glass, including its refractive index, can vary depending on its composition and temperature, making it important to consult specific data for particular applications. Overall, glass remains a foundational material in optics, its wide applicability owed to its tunable properties and general robustness.

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