Crystals Materials
Germanium (Ge) be used for windows, infrared optical lenses (spherical and/or non-spherical), prisms, and other optical components.
  • Surface Quality: 10/5 Scratch/Dig MIL-O-1380A
  • Parallelism: < 10″
  • Perpendicularity: < 5'
  • Clear Aperture: > 90%
  • Surface Flatness: < λ/10 @ 632.8 nm
  • Coating: AR/HR/PR coating upon customer's request
  • Quality Warranty Period: One year
  • Chalcogenide glasses, also known as infrared glasses or germanium glasses, possess excellent optical transparency, minimal refractive index and thermal dispersion changes. Within the range of 1-14μm, germanium glass exhibits minimal thermal defocusing, making it easier to design color-corrected infrared optical systems. It is an ideal choice for applications that require combining with other infrared materials. Germanium glass can be used for windows, infrared optical lenses (spherical and/or non-spherical), prisms, and other optical components.

    Specifications of Germanium (Ge)
    Material Germanium (Ge)
    Diameter 3mm ~ 300mm
    Thickness >0.1mm
    Dimension Tolerance +0/-0.02mm
    Angle Tolerance ±15 arcsec
    Surface Accuracy λ/10 @ 633nm
    Surface Quality S/D 10–5
    Pyramid Tolerance <5 arcmin
    Bevel <0.25mm X 45°
    Coating Available upon request
    Physical and optical properties
    Crystal Structure Cubic
    Density 5.27 g/cm³
    Crystal Size <100 μm
    Impurities None > 0.05 mm
    Resistivity > 10^12 ohm-cm
    Dielectric Constant Consult Technical Personnel
    Absorption Coefficient @10.6μm <0.0005 cm^-1
    Thermal Optical Coefficient (dn/dT) @10.6μm 6.1 × 10^-5 ℃
    Refractive Index Uniformity @0.6328μm <3 × 10^-6
    Thermal Conductivity @20°C 0.18 W/cm/℃
    Specific Heat 0.356 J/g/℃
    Linear Expansion Coefficient @20°C 7.57 × 10^-6/℃
    Young's Modulus 67.2 GPa (9.75 × 10^6 psi)
    Fracture Modulus 55.1 MPa (8,000 psi)
    Knoop Hardness 105-120 kg/mm²
    Poisson's Ratio 0.28
    Fracture Toughness 0.5 × 10^6 N/m^3/2

    Stock specification list

    If need other specifications and quantities products, please contact us(
    Part Number Face size Thickness Surface Quality Coating
    WIN-080-020-Ge Dia 8.00 mm 2.00 mm 40/20 UnCoated
    WIN-127-020-Ge Dia 12.70 mm 2.00 mm 40/20 UnCoated


  • Anti-reflection coatings are available at your specified wavelength.
  • Be sure to wear laser safety goggles when checking optical path and adjusting optical axis.
  • To inquiry or order a finished Germanium (Ge) windows, please specify the specification listed above, for common application, we only need to know the main specification: Cr-dopant concentration, sizes, and coating. For special request, please specify specification in details for evaluation and fabrication.
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