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Custom AMTIR

AMTIR (Amorphous Material Transmitting Infrared Radiation – Ge33As12Se55) is a glass-like, chalcogenide material similar to germanium in its optical properties, but with a lower refractive index. AMTIR-1 has a broad transmission range between 0.75 to 14µm, but with optimal performance in the 8-12µm waveband.
Below is a brief summary of AMTIR-1’s optical properties:

Transmission range

0.75 to 14.0µm

Refractive Index

2.4981 @ 10µm


4.4 g/cm3

Melting Point

> 360°C



Knight Optical supplies high quality AMTIR-1 components, including windows, lenses and prisms, made to your custom specification. We can offer uncoated and coated optics, including broadband antireflective (BBAR) and diamond-like carbon (DLC) coatings. Our typical manufacturing specifications are listed below however we are always expanding our capabilities so if your requirements are not mentioned below, please contact our technical sales team who will guide you through your enquiry.


Windows: < 5mm to 200mm+

Lenses: < 5mm to 150mm+

Form error (@633nm)

< 0.25 waves

Centration /parallelism

< 1 arc minute


< 40/20

Typical coatings

BBAR coating @ 2-14µm

DLC coating @ 2-14µm

All optics are tested in our state-of-the-art metrology laboratory by our highly trained technicians, so you can be confident that your optical components will meet your requirements.

Additional Information

  • A chalcogenide glass is produced, as the name implies, from a chalcogen chemical element. AMTIR-1 is manufactured from selenium, germanium and arsenic.
  • Though its optical properties are similar to  germanium, as well as its similar density, it has a lower refractive index, meaning it pairs well with germanium in an achromatic doublet for colour correction within an optical system.
  • AMTIR-1 has a low change in refractive index with temperature which is beneficial in systems with temperature fluctuations where it can prevent thermal defocussing.


  • AMTIR-1 has a maximum operating temperature of 300°C .
  • It performs well in the 8-12µm wavelength range where both its dispersion and absorption are at their lowest.

Typical Applications

Thermal Imaging Systems
  • Due to its broad transmission range and refractive index homogeneity AMTIR-1 is used in thermal imaging systems.
YAG laser system
  • AMTIR-1 optics are often used in Nd:YAG laser system which are fairly low powered and typically emit light at 1064nm.

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