Interesting Facts About Germanium
Germanium single crystal has high hardness, good thermal conductivity, insoluble in water, and a transmission band of 2-12 μm. It is a very commonly used infrared optical material. Currently widely used in infrared imaging systems and infrared spectrometer systems. Germanium single crystal is also used as the base material for various infrared filters.
High-purity germanium single crystal has a high refractive index, is transparent to infrared rays, and does not transmit visible light and ultraviolet rays. It can be used as a germanium window, prism or lens that specifically transmits infrared light.
Germanium’s ability to absorb light continues to strengthen as the temperature rises. Above 100 degrees Celsius, it has a significant impact on the light transmittance, seriously affecting the performance of the optical system. Germanium components are usually coated with anti-reflective coatings due to their high surface reflectivity.
Germanium windows coated at 3 to 12 μm are used in mid-infrared and multispectral applications, and germanium windows at 8 to 12 μm are commonly used in thermal imaging and infrared imaging systems.
Germanium Optical Properties
High refractive index: The refractive index of germanium lenses is approximately 4.0 in the 2-14μm band, which gives them excellent optical performance in infrared imaging systems.
Wide spectral working range: The transmission range of germanium lenses can reach 2-16μm, making it suitable for a variety of infrared band applications.
Chemical stability: Germanium does not react easily with air, water, alkali metals and acids (except nitric acid), and has good chemical stability.
Processing and Manufacturing
Diamond Turning: To machine compact, lightweight systems, manufacturers often use aspherical lenses, which require diamond turning to obtain precise surface shapes.
Anti-reflection coating: In order to improve the transmittance of germanium lenses, anti-reflection coatings are often coated on their surfaces. Commonly used bands include 3-12μm or 8-12μm.
Specifications:
| Diameter | 3mm-200mm |
| Edge Thickness Range | ≥0.7mm |
| Medium Thick Range | ≥1mm |
| Angle Processing Range | 0°~65° |
| Lost Height Processing Range | ≤21mm |
| Caliber and Medium Thickness Ratio | 17以内 |
| Pv | 0.1μm |
| Ra | 4nm-10nm |
| △N | 0.3-1.5 |
| Coating | AR coating, reflective film, metal film |
Why Choose Bote
- High resistivity hemispherical lenses available
- Available in AR or DLC coating
- Available in various diameters and focal lengths
Bote germanium optics are tested on Zygo interferometers and Agilent spectrophotometers as standard to ensure exceptional quality. For your information, please see our typical manufacturing specifications. You can also contact us for manufacturing limitations or custom specifications.