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Germanium Domes

  • Maximum Diameter: 280mm
  • Wide wavelength range of 2-14μm
  • Fit for both MWIR and LWIR thermal imaging cameras
  • Excellent for defense, security and aerospace application
Curves All Inquire Us  
Materials Optical grade germanium single crystals Diameter Range ~280mm
Thickness Tolerance ±0.2mm (Optional:
±0.1mm or ±0.05mm)
Surface Quality 60/40 S/D
Frings (N) customized Irregularity (delta N) customized
Chamfer 0.1~0.3mmx45degree Coating(optional) AR/AR@7-14μm
See the curves below

Physical and Optical Properties:

Transmission Range 1.8 to 23μm (1) Refractive Index 4.0026 at 11μm (1)(2)
Reflection Loss 53% at 11μm (2 surfaces) Absorption Coefficient <0.027 cm-1 @ 10.6μm
Reststrahlen Peak n/a dn/dT 396 x 10-6 /°C (2)(6)
dn/dμ = 0 Almost constant Density 5.33 g/cc
Melting Point 936 °C (3) Thermal Conductivity 58.61 W m-1 K-1 at 293K (6)
Thermal Expansion 6.1 x 10-6 /°C at 298K (3)(4)(6) Hardness Knoop 780
Specific Heat Capacity 310 J Kg-1 K-1 (3) Dielectric Constant 16.6 at 9.37 GHz at 300K
Youngs Modulus (E) 102.7 GPa (4) (5) Shear Modulus (G) 67 GPa (4) (5)
Bulk Modulus (K) 77.2 GPa (4) Elastic Coefficients C11=129; C12=48.3; C44=67.1 (5)
Apparent Elastic Limit 89.6 MPa (13000 psi) Poisson Ratio 0.28 (4) (5)
Solubility Insoluble in water Molecular Weight 72.59
Class/Structure Cubic Diamond, Fd3m    

Germanium domes is a special type of windows which is ideal for IR applications(especially for defense and aerospace application) with its broad transmission range and opacity in the visible portion of the spectrum. Germanium domes is commonly used in IR thermal imaging cameras typically operating in the 2 µm to 14 µm spectral range, covers the LWIR (8-12μm) and MWIR (3-5μm) thermal imaging wavelength range. Germanium windows can be AR coated with Diamond (DLC coating or Hard carbon coating) producing an extremely tough front optic.

Technical Images:

1. Transmission curve for Ge windows with coating AR/AR of 1mm thickness

2.Transmission curve for Ge windows with coating AR/AR of 3mm thickness

3.Transmission curve for Ge windows with coating AR/DLC of 3mm thickness