Germanium

Germanium

Germanium



Details


Features

Germanium is a versatile infrared material commonly used in imaging systems and instruments in the 2 to 12 microns spectral region. It is used as a substrate for lenses, windows, and output couplers for low-power CW as well as pulsed TEA, CO2 lasers. The lowest absorbing Ge optics are limited to a throughput power range of 50 to 100 watts before thermal lensing or thermal runaway. These problems are minimized by properly heatsinking the optic and carefully cleaning contaminated optical surfaces.

Ge is non-hygroscopic and non-toxic, has good thermal conductivity, excellent surface hardness, and good strength. UOC carefully monitors the 10.6µm Ge absorptivity for use in laser applications to assure that thermal runaway and fracture do not occur.

One ideal laser application for Ge is a > 99% reflecting back mirror for a CO2 laser with built-in power meters. A high-reflecting, low-absorption dielectric coating is on one side and an AR coating on the other. The laser operates on the feedback from the high-reflecting side, but enough power leaks through for monitoring by a power meter. Unioriental supplies these optics for a number of commercial laser applications. 


Specifications
1.Size from Φ5mm to Φ320mm, and Φ 400 for polycrystalline Ge
2.Thickness 1mm to 20mm 
3.Optical parts available from lenses, mirrors to windows and prisms
4.Anti-reflection, High-refelction and Output coupler coatings are available upon request 


*Note: Other parts and coatings are available upon requests 


Optical properties
Transmission Range

1.8 to 23 microns

Refractive Index

4.0 at 10.6 microns

Reflection Loss

52.9% at 10.6 microns (2 surfaces)

dN/dT

396 x 10-6/°C


Physical properties 
Density

5.323 gm/cm3

Melting Point

938.25°C

Thermal Conductivity

60.2 Wm-1K-1 at 300K

Thermal Expansion

6.0 x 10-6K

Hardness

Knoop 550

Specific Heat Capacity

233.22 J mol-1K-1

Dielectric Constant

16.0

Youngs Modulus (E)

103GPa

Shear Modulus (G)

41 GPa

Bulk Modulus (K)

75 GPa

Poisson Ratio

0.26


Chemical properties 
Solubility

Insoluble in water. Soluble in hot H2SO4 and aqua-regia.

Molecular Weight

72.61

Class/Structure

Cubic

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