Germanium (Ge) Window
| Machinable shape | Circle, rectangle, polygon and other shapes |
| Size range | Diameter (maximum diagonal)：Φ8-Φ60mm |
| Thickness：0.05-50mm | |
| Facial type | Reflected PV better than 1/4 λ， Transmission PV is better than 1/10 λ |
| Fineness | 10-5 20-10 40-20 |
| Surface roughness | <5nm |
| Parallelism | <20″ |
| Coating | Customized according to customer requirements |
Germanium (Ge) single crystal is a chemically inert material, and its transmission spectrum range is 2-12 μ m. It is a commonly used infrared optical material. It has the characteristics of high hardness, good thermal conductivity and insoluble in water. It is widely used in infrared imaging system and infrared spectrometer system. The mechanical properties and thermal conductivity of germanium single crystal are good, at 10.6 μ The absorption of m is very small. The window processed with germanium single crystal is the first choice for CO2 laser, and can also be used to make substrates for various filters.
The application of germanium in infrared optics is mainly used to manufacture infrared optical lenses and protect infrared optical windows of infrared optical lenses. More than 60% of middle and low end infrared optical lenses are made of single crystal germanium, and 50% of high-end infrared optical lenses are made of single crystal germanium. Germanium materials are widely used in infrared lenses. In the civil infrared lens, the single set of small and medium aperture lens consumes about 250g of germanium, and the large aperture lens consumes about 2500g of germanium.
Civil infrared window is mainly used in various monitoring thermal imagers and night assistant pilots. The civil field is mainly used in security, civil vehicles, civil ships, civil aircraft, police, etc.
Physical Properties
| Density（g/cm3） | 5.33 |
| Melting point（℃） | 936 |
| Dielectric constant | 16.6@9.37GHz（300K） |
| Coefficient of thermal expansion （1/℃） | 6.1*10^-6@298K |
| Bulk modulus（GPa） | 77.2 |
| Shear modulus（GPa） | 67 |
| Thermal conductivity | 58.61@293K |
| Heat capacity（J/k.m.s） | 0.31 |
| Hardness (knoop) (kg/mm2) | 780 |
| Young’s modulus (GPa) | 102.7 |
| Poisson's ratio | 0.28 |
| Coefficient of elasticity | C11=129 C11=48.3 C11=67.1 |
Optical Properties
| Through wavelength range | 2000nm-12000nm |
| Absorption coefficient | 1.1.3*10^-3@3800nm |
| 2.3*10^-2@10600nm | |
| Thermo-optic coefficient, dn/dT(1/K） | 4.08*10^-4@10600nm |
Change of refractive index with wavelength
| Wavelength (nm) | Refractive index (n) | Wavelength (nm) | Refractive index (n) |
| 2200 | 4.0879 | 8000 | 4.0057 |
| 3000 | 4.0451 | 9000 | 4.0040 |
| 3800 | 4.0267 | 10600 | 4.0028 |
| 5000 | 4.0160 | 11000 | 4.0025 |
| 6000 | 4.0107 | 12000 | 4.0021 |
| 7000 | 4.0079 | 13000 | 4.0018 |
Website of this article：http://www.longsee-laser.com/en/Ge/13.html
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