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Home > Products > Lenses > Germanium Lenses
Germanium Lenses

●  Transmission wavelength range of 2-14 μm 

●  Various types of IR coating available


Germanium lenses are ideal for IR applications with its broad transmission range and opacity in the visible portion of the spectrum. Germanium is commonly used in IR imaging systems typically operating in the 2 µm to 14 µm spectral range, covers the LWIR (8-12μm) and MWIR (3-5μm) thermal imaging wavelength range.


Vanrun OE provides a variety of customized germanium lenses. 

The main series and specifications are as follows:

Germanium Plano convex lens, bi-convex lens / double convex lens

Germanium Plano concave lens, bi-concave lens / double concave lens

Germanium Crescent lens / concave convex lens

Germanium Cylindrical lens and rod lens

Specifications of germanium lenses:

Material:

Optical Infrared grade germanium single crystals

Dimension Range:

Dia. 5mm to 300mm

Dimension Tolerance:

+/-0.05mm, +/-0.1mm

Thickness Range:

>0.5mm

Thickness Tolerance:

+/-0.25mm

Surface Quality:

 60-40, 80-50 (MIL13830)

Surface Accuracy:

1/4 lambda @ 633nm

Centerial:

1 arc min

Chamfer:

protective, 0.2 to 0.5x45 Degree

Coating:

IR+DLC, optical coatings are avaliable upon request

Proterties of sapphire crystal:
Physical and optical proterties

Transimission Range1.8 to 23um
Refractive Index4.0026 @ 11um
Reflection Loss53% @ 11um
Absorption Coefficient<0.027 cm-1 @ 10.6um
Reststrahlen PeakN/A
dn/dT396 x 10-6 /°C
dn/du = 0almost constant
Density5.33 g/cc
Melting Point936°C
Thermal Conductivity58.61 W m-1 K-1 @ 293K
Thermal Expansion6.1 x 10-6/°C @ 298K
HardnessKnoop 780
Specific Heat Capacity310 J Kg-1 K-1
Dielectric Constant16.6 @ 9.37GHz @300K
Youngs Modulus (E)102.7 GPa
Shear Modulus (G)67 GPa
Bulk Modulus (K)77.2 GPa
Elastic CoefficientsC11=129 C12=48.3 C44=67.5
Apparent Elastic Limit89.6MPa （13,000 psi)
Poisson Ratio0.28
Solubilityinsoluble in water
Molecular Weight72.59
Class/StructureCubic Diamond, Fd3m