IR Glass

IR materials have distinct properties that allow them to perform well in the infrared spectrum. IR Fused Silica, Germanium, Silicon, Sapphire, and Zinc Sulfide/Selenide each have strengths for infrared applications. IR optical glasses


Germanium (Ge)

Optimum Transmission Range:

Ideal Applications: LWIR - MWIR

2 - 14μm

Thermal imaging (when AR coated) 

 Rugged optical situations

Germanium has a dark grey smoky appearance with a refractive index of 4.024 with low optical dispersion. It has a considerable density with a Knoop Hardness (kg/mm2): 780.00 allowing it to perform well for field optics in rugged conditions. 

Silicon (S)

Optimum Transmission Range:

Ideal Applications: MWIR

1.2 to 9μm

NIR imaging, IR spectroscopy, MWIR detection systems

Less dense than Ge or ZnSe

Silicon has blue-gray appearance with a high thermal capacity that makes it ideal for laser mirrors and silicon wafers for the semiconductor industry. It has a refractive index of 3.42. Silicon components are used in electronic devices is because its electrical currents can pass via the silicon conductors much quicker compared to other conductors. AR coating is recommended for most applications. 

Zinc Selenide (ZnSe)

Optimum Transmission Range: Ideal Applications:

0.6 to 18 μm

CO2 lasers and thermometry and spectroscopy
Lenses, windows, and FLIR systems 

Zinc selenide is a light-yellow, solid compound comprising zinc and selenium. It is created by synthesis of Zinc vapour and H2 Se gas, forming as sheets on a graphite substrate. It is known for its low absorption rate and which allows for excellent uses for CO2 lasers. 

Zinc Sulfide (ZnS)

Optimum Transmission Range: Ideal Applications: LWIR - MWIR

0.6 to 18 μm

Visible and mid-wave or long-wave infrared sensors
Structurally stronger and more chemically resistant than ZnSe

Zinc Sulfide is an excellent choice for infrared sensors it transmits well in the IR and visible spectrum. It is typically a cost effective choice over other IR materials. 


 IR transmission chart

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