Ge has high refractive index, The transmission wavelength for Monocrystal Germanium is 2-12um, it is a common infrared crystal which is widely used for infrared image system and infrared spectrograph systems. Ge has a small absorbency at 10.6um. It is a good material for CO2 lens and windows.
Product Details
Ge has high refractive index, The transmission wavelength for Monocrystal Germanium is 2-12um, it is a common infrared crystal which is widely used for infrared image system and infrared spectrograph systems. Ge has a small absorbency at 10.6um. It is a good material for CO2 lens and windows. Three kinds AR Coating are available: 3-5 μm for mid-infrared applications. 3-12 μm for broadband multispectral applications, and 8-12 μm for thermal imaging applications.Germanium optical materials are also suitable to be used with wavelength of 8-12μm.Germanium is highly affected by temperature, and the transmittance decreases with increasing temperature; therefore, they can only be used below 100C.The density of germanium (5.33 g/cm3) should be taken into account when designing systems with strict weight requirements.Germanium is mainly used in thermal imaging systems and forward looking infrared (FLIR).Germanium has a Knoop hardness of 780, about twice that of magnesium fluoride, making it suitable for IR applications in variable optics.
Optical Properties
| Transmission Wavelength | 2000nm—12000nm |
| Absorptivity (1/cm) | 1.3*10-3 @ 3800nm 3*10-2 @ 10600nm |
| Thermo-optical coeffecient, dn/dT (1/k) | 4.08*10-4 @10600nm |
| Electrical resistivity | 5-40 Ω.cm 1-5Ω.cm >50Ω.cm |
Refractive index range(20℃)
| 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 |
Manufacture Specifications
| Diameter | 5-270mm |
| Diameter Tol. | +/-0.1 |
| Surface Quality | 60-40 standard |
| Flatness | 1/4 lambda |
| Chamfer | 0.25mmx45degree |
| Focal Length Tol. | +/-1% |
| Coating | 2-14um |
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