Germanium (Ge) wedge prisms
The refractive index of single crystal germanium material is higher than 4.0, and the wedge prism made of single crystal germanium has strong deflection ability to infrared light.
Such as a 2-degree germanium wedge prism can deflect infrared light by 6 degrees.
Germanium material is softer than other optical materials, and there are many surfaces should be polished,so the surface quality of germanium prism is easier to be destroyed in the processing.
Because germanium material does not penetrate the visible light, it can not use the self-collimation method to measure the angular accuracy as other materials'prisms.
These factors lead to high production cost of germanium prism.
In infrared system, it is sometimes necessary to deflect the infrared light (especially the light with 8-14um wavelength) at a certain angle, and germanium prism is very suitable for it.
Since the Refractive index of single crystal germanium is 4.0, its critical angle is only 14.5 degrees, it is very conducive to the propagation of light beam in the prism.
We have customized various germanium prisms for many university laboratories and other similar research departments. We have many years of experience in this field.
We can customize germanium prisms for you.Or you just need to tell us what you need to achieve,Our engineers can recommend or design suitable prisms for you.
More details please contact us.
Production Line
Optical Properties of Germanium Prism
| Material | Single Crystal Germanium |
| AR Coating Range | 3-5um,8-12um,3-11um |
Reflectance over
AR Coating Range @ 0° AOI | Ravg < 2%,3-5um or 8-12um Ravg<5%,3-11um |
Transmission over
AR Coating Range @ 0° AOI | Tavg > 94%,3-5um or 8-12um |
| Diameter Tolerance | +0.0/-0.1 mm |
| Thickness Tolerance | ±0.1 mm |
| Focal Length Tolerance | ±2% |
| Surface Quality | 60-40 Scratch-Dig |
Surface Flatness
(Plano Side) | λ/2 at 633nm |
Spherical Surface Powerc
(Convex Side) | 1.5λ at 633nm |
Surface Irregularity
(Peak to Valley) | λ/2 at 633nm |
| Centration | <3 arcmin |
| Clear Aperture | >Ø10.16 mm (Ø1/2" Lenses)
>Ø20.32 mm (Ø1" Lenses) |
| Design Wavelength | 10.6 μm |
Transmittance of Antireflection coatings:
Germanium properties:
| Chemical Formula | Ge |
| Crystal Form | Poly or Single Crystal |
| Crystal Class | Cubic |
| Resistivity, Ohm*cm | 0.01-40 |
| Lattice Constant, Å | 5.66 |
| Molecular Weight | 72.6 |
| Density, g/cm3 at 300 K | 5.33 |
| Dielectric Constant for 9.37 x 109 Hz at 300 K | 16.6 |
| Melting Temperature, K | 1210 |
| Thermal Conductivity, W/(m K) at 293 K | 59 |
| Thermal Expansion, 1/K at 298 K | 6.1 x 10-6 |
| Specific Heat, cal/(g K) at 273-373 K | 0.074 |
| Debye Temperature, K | 370 |
| Bandgap, eV | 0.67 |
| Solubility in water | None |
| Knoop Hardness, kg/mm2 | 800 |
| Mohs Hardness | 6.3 |
| Young's Modulus, GPa | 102.66 |
| Shear Modulus, GPa | 67.04 |
| Bulk Modulus, GPa | 77.86 |
| Poisson's Ratio | 0.278 |
Infrared Elements Selection Guide
Product Tags:
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High Precision Infrared Prism Optical Infrared Ge Germanium Wedge Prism Images
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