Germanium Lens

Release time：2022-02-10 10:02viewed：times

Germanium Lens

The transmittance range of optical germanium material is 2-14um, and its refractive index is as high as 4. Germanium lens and germanium window are widely used in thermal imaging system.
Because germanium material has high refractive index, the surface reflectivity is very high (R>30%), so optical germanium elements usually need AR coating.

Germanium lenses specifications:

	Standard precision	High-precision
Dimension Tolerance	φ5-250mm+0/-0.2	φ3-350mm+0/-0.2
Thickness Tolerance	1-50mm+/-0.1	1-50mm
Centration	3 arc minute	1 arc minute
Surface Quality	60/40	20/10
Power(fringe@633nm)	N<λ/2@633nm（in 25mm）	N<λ/10@633nm（in 25mm）
Clear Aperture	>90%	>95%
Chamfer	Protected <0.5mmx45deg	Protected <0.5mmx45deg

Germanium Coating

Custom germanium windows ,lenses and prisms are available in any size and configuration. Anti-reflection coatings can be applied for 2-14µm or 8-12µm (BBAR coating or DLC/BBAR) depending on your custom application.

Germanium properties
Chemical Formula	Ge
Crystal Form	Poly or Single Crystal
Crystal Class	Cubic
Resistivity, Ohm*cm	5-40
Lattice Constant, Å	5.66
Molecular Weight	72.60
Density, g/cm³ at 300 K	5.33
Dielectric Constant for 9.37 x 10⁹ Hz at 300 K	16.6
Melting Temperature, K	1210
Thermal Conductivity, W/(m K) at 293 K	59
Thermal Expansion, 1/K at 298 K	6.1 x 10^-6
Specific Heat, cal/(g K) at 273-373 K	0.074
Debye Temperature, K	370
Bandgap, eV	0.67
Solubility in water	None
Knoop Hardness, kg/mm²	800
Mohs Hardness	6.3
Young's Modulus, GPa	102.66
Shear Modulus, GPa	67.04
Bulk Modulus, GPa	77.86
Poisson's Ratio	0.278

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