Germanium(Ge) Window
Germanium (Ge) windows are available off-the-shelf with three anti-reflection coating options: 3 – 5μm for mid-infrared applications, 3 – 12μm for...
Germanium(Ge) Window
Germanium (Ge) windows are available off-the-shelf with three anti-reflection coating options: 3 – 5μm for mid-infrared applications, 3 – 12μm for broadband multispectral applications, or 8 – 12μm for thermal imaging applications. Due to its high index of refraction (around 4.0 from 2 – 14μm), an anti-reflection coating is recommended on these germanium windows for sufficient transmission in the region of interest. G...
- ManufacturerOST Photonics
- CategoryInfrared Window
- Lead TimeQuoted per order
- CustomizationSize, orientation and surface finish to drawing
Germanium (Ge) windows are available off-the-shelf with three anti-reflection coating options: 3 – 5μm for mid-infrared applications, 3 – 12μm for broadband multispectral applications, or 8 – 12μm for thermal imaging applications. Due to its high index of refraction (around 4.0 from 2 – 14μm), an anti-reflection coating is recommended on these germanium windows for sufficient transmission in the region of interest. Germanium is subject to thermal runaway, meaning that the transmission decreases as temperature increases. As such, these germanium windows should be used at temperatures below 100°C. Germanium’s high density (5.33 g/cm3) should be considered when designing for weight-sensitive systems. The Knoop Hardness of germanium (780) is approximately twice that of magnesium fluoride, making it ideal for infrared applications requiring rugged optics.
Advantages
1 ) Uncoated or with AR Coatings Designed for a Variety of IR Ranges
2 ) Minimal Chromatic Aberration Due to Low Dispersion
3 ) Ideal for Infrared Applications Requiring Rugged Optics
Specifications
1 ) Diameter: 3~300mm
2 ) Diameter Tolerance: +/-0.2mm
3 ) Thickness Tolerance: +/-0.03mm
4 ) Aperture: >90%
5 ) Surface Quality: 80/50~10/5 (S/D)
6 ) Parallelism: <1 arc minute
7 ) Chamfer: 0.3-0.5mmx45°
8 ) Coating: AR/AR@7-14μm; DLC/AR@7-14μm; BBAR/BBAR@3-12μm
Optical Properties
| Transmission Range | 1.8 to 23 micron |
| Refractive Index | 4.0026 at 11 micron |
| Refractive Loss | 53% at 11 micron |
| Crystal/Class Structure | Cubic Diamond, Fd3m |
| Cleavage Plane | (111),non-perfect |
Thermal Properties
| Thermal Expansion | 6.1×10－6 / ℃ at 298K |
| Thermal Conductivity | 58.61W m－1K－1 at 293K |
| Melting Point | 936 ℃ |
| Specific Heat Capacity | 310 J Kg－1K－1 |
Mechanical Properties
| Density | 5.33 g/cc |
| Hardness(Knoop) | Knoop 780 |
| Youngs Modulus | 108.7 GPa |
| Shear Modulus | 67 GPa |
| Bulk Modulus | 77.2 GPa |
| Poisson Ratio | 0.28 |
| Elastic Limit | 89.6 MPa(13000psi) |
| Molecular Weight | 72.59 |
Chemical Properties
| Solubility | Insoluble in water |
Technical Images
Other Infrared Window Materials
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