Germanium Windows are widely used in thermal imaging systems, FLIR systems, and demanding IR applications where high transmission across the 2–14 μm range and low chromatic aberration are required.
Avantier manufactures custom and stock germanium windows with DLC and BBAR coating options that offset the material’s high refractive index (4.0 across 2–14 μm) and minimize Fresnel reflection losses, supporting prototype runs through full production scale.
Germanium windows are used across a broad range of infrared applications, including:
- Thermal imaging systems (military, industrial, medical)
- FLIR and IR surveillance cameras
- Gas detection and spectroscopy
- Aerospace and drone imaging
- Environmental monitoring
- Remote sensing
Custom Design Specifications
Custom germanium windows are typically specified by aperture dimensions, thickness and parallelism tolerances, surface quality, and coating requirements.
The most common design parameters are summarized below.
| Specification | Detail |
| Diameter Range | 2 mm – 100 mm |
| Diameter Tolerance | +0/-0.05 mm |
| Thickness Tolerance | +0.01/-0.03 mm |
| Coating Options | 2–14 µm BBAR 8–12 µm BBAR or DLC/BBAR |
| Flatness | λ/2 (factory standard) |
| Parallelism | < 3 arc minutes |
| Surface Finish | 20-10 scratch-dig, no digs |
| Bevel | Protective Bevel |
| Transmission Rate | > 47.5% @ 3.7–4.8 µm |
| Refractive Index | 4.0 (2–14 µm) |
Stock Germanium Windows
Avantier offers high-performance stock Germanium (Ge) windows for IR and optical applications. Sizes range from 5mm to 150mm with anti-reflective coatings to meet specific needs. Precision manufacturing ensures exceptional flatness, parallelism, and surface finish for optimal performance in thermal imaging, IR lasers, and harsh environments.
| Part Number | CA (mm) | Diameter (mm) | Thickness (mm) | Coating Specification | Parallelism (arcmin) | Surface Flatness (P-V) | Surface Quality |
|---|---|---|---|---|---|---|---|
| AVTZC-0001 | 4.50 | 5.00 +0.0/-0.1 | 1.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0002 | 4.50 | 5.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0003 | 4.50 | 5.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0004 | 9.00 | 10.00 +0.0/-0.1 | 1.50 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0005 | 9.00 | 10.00 +0.0/-0.1 | 1.50 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0006 | 9.00 | 10.00 +0.0/-0.1 | 1.50 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0007 | 9.00 | 10.00 +0.0/-0.1 | 1.50 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0008 | 11.25 | 12.50 +0.0/-0.1 | 1.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0009 | 11.25 | 12.50 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0010 | 11.25 | 12.50 +0.0/-0.1 | 1.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0011 | 11.25 | 12.50 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0012 | 11.25 | 12.50 +0.0/-0.1 | 2.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0013 | 11.25 | 12.50 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0014 | 11.25 | 12.50 +0.0/-0.1 | 2.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0015 | 11.25 | 12.50 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0016 | 11.25 | 12.50 +0.0/-0.1 | 3.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0017 | 11.25 | 12.50 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0018 | 11.25 | 12.50 +0.0/-0.1 | 3.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0019 | 11.25 | 12.50 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0020 | 18.00 | 20.00 +0.0/-0.1 | 2.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0021 | 18.00 | 20.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0022 | 18.00 | 20.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0023 | 18.00 | 20.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0024 | 22.50 | 25.00 +0.0/-0.1 | 1.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0025 | 22.50 | 25.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0026 | 22.50 | 25.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0027 | 22.50 | 25.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0028 | 22.50 | 25.00 +0.0/-0.1 | 2.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0029 | 22.50 | 25.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0030 | 22.50 | 25.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0031 | 22.50 | 25.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0032 | 22.50 | 25.00 +0.0/-0.1 | 3.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0033 | 22.50 | 25.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0034 | 22.50 | 25.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0035 | 22.50 | 25.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0036 | 22.50 | 25.00 +0.0/-0.1 | 5.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0037 | 22.50 | 25.00 +0.0/-0.1 | 5.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0038 | 22.50 | 25.00 +0.0/-0.1 | 5.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0039 | 22.86 | 25.40 +0.0/-0.1 | 3.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0040 | 22.86 | 25.40 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0041 | 22.86 | 25.40 +0.0/-0.1 | 3.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0042 | 22.86 | 25.40 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0043 | 27.00 | 30.00 +0.0/-0.1 | 1.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0044 | 27.00 | 30.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0045 | 27.00 | 30.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0046 | 27.00 | 30.00 +0.0/-0.1 | 3.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0047 | 27.00 | 30.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0048 | 27.00 | 30.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0049 | 27.00 | 30.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0050 | 36.00 | 40.00 +0.0/-0.1 | 2.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0051 | 36.00 | 40.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0052 | 36.00 | 40.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0053 | 36.00 | 40.00 +0.0/-0.1 | 4.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0054 | 36.00 | 40.00 +0.0/-0.1 | 4.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0055 | 36.00 | 40.00 +0.0/-0.1 | 4.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0056 | 36.00 | 40.00 +0.0/-0.1 | 4.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0057 | 45.00 | 50.00 +0.0/-0.1 | 1.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0058 | 45.00 | 50.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0059 | 45.00 | 50.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0060 | 45.00 | 50.00 +0.0/-0.1 | 1.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0061 | 45.00 | 50.00 +0.0/-0.1 | 2.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0062 | 45.00 | 50.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0063 | 45.00 | 50.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0064 | 45.00 | 50.00 +0.0/-0.1 | 2.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0065 | 45.00 | 50.00 +0.0/-0.1 | 3.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0066 | 45.00 | 50.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0067 | 45.00 | 50.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0068 | 45.00 | 50.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0069 | 45.72 | 50.80 +0.0/-0.1 | 3.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0070 | 45.72 | 50.80 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0071 | 45.72 | 50.80 +0.0/-0.1 | 3.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0072 | 45.72 | 50.80 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0073 | 67.50 | 75.00 +0.0/-0.1 | 3.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0074 | 67.50 | 75.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0075 | 67.50 | 75.00 +0.0/-0.1 | 3.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0076 | 67.50 | 75.00 +0.0/-0.1 | 5.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0077 | 67.50 | 75.00 +0.0/-0.1 | 5.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0078 | 67.50 | 75.00 +0.0/-0.1 | 5.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0079 | 67.50 | 75.00 +0.0/-0.1 | 5.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0080 | 68.58 | 76.20 +0.0/-0.1 | 5.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0081 | 68.58 | 76.20 +0.0/-0.1 | 5.00 ±0.1 | Ravg <3.0% @ 3 – 5μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0082 | 68.58 | 76.20 +0.0/-0.1 | 5.00 ±0.1 | Ravg <5.0% @ 3 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0083 | 68.58 | 76.20 +0.0/-0.1 | 5.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0084 | 90.00 | 100.00 +0.0/-0.1 | 6.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0085 | 90.00 | 100.00 +0.0/-0.1 | 6.00 ±0.1 | Ravg <3.0% @ 8 – 12μm | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0086 | 112.50 | 125.00 +0.0/-0.1 | 6.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
| AVTZC-0087 | 135.00 | 150.00 +0.0/-0.1 | 8.00 ±0.1 | Uncoated | <1 | λ/10 @ 10.6μm | 60-40 |
Also available in volume pricing, please contact Avantier for details.
Please note that prices are subject to fluctuation and may change without prior notice. For the most accurate and up-to-date pricing information, kindly contact our office. Additional shipping fees will be calculated and added to your total order.
Key Capabilities – Why Germanium?
Broad Transmission Range in Infrared (IR) Spectrum: Germanium windows transmit efficiently across the infrared spectrum, spanning from 2 µm to 14 µm. This unique characteristic makes them suitable for IR laser applications, facilitating the efficient passage of IR radiation while maintaining opacity to UV and visible light. The broad transmission range also makes them ideal for various IR applications, including satellite imaging and thermal vision systems.
Minimal Chromatic Aberration and Low Dispersion: Low dispersion keeps chromatic aberration to a minimum, supporting sharp, low-distortion imaging. This ensures superior image quality and reduced color distortion, making them ideal for applications that necessitate precise optical performance, such as weight-sensitive systems requiring accurate imaging.
High Index of Refraction and Anti-Reflection Coating: With a high refractive index (4.0 from 2 – 14 µm) , germanium generates significant surface reflection losses without a coating. Anti-reflection coatings like BBAR (Broadband Anti-Reflection) coatings offset these losses, ensuring maximum transmission properties.
Robustness and Durability in Harsh Environments: Germanium’s (Ge) composition is heavy and hard, boasting a Knoop Hardness of 780—nearly double that of MgF. With a density of 5.33 g/cm3, it becomes a notable choice for space applications, where durability is favored in extreme environments. Transmission performance declines sharply above 100°C, a limitation known as thermal runaway, so germanium suits applications with stable operating temperatures below that threshold.Despite its sensitivity to temperature, germanium excels in IR laser applications, particularly in scenarios necessitating resilient optics. Additionally, it serves as a long pass filter, transmitting wavelengths greater than 2 µmm and resists air, water, alkalis, and most acids while maintaining high scratch resistance.
Applications in IR and Optical Systems
The versatility of germanium windows enables their deployment across various industries, showcasing their prowess in specific applications:
- IR Laser Systems: High transmission and durability suit germanium windows to IR laser applications, particularly compact, weight-sensitive systems.
- Aerospace: High hardness and scratch resistance withstand flight-environment mechanical stress, while low weight suits payload constraints.
- Industrial Applications: Chemical inertness to acids, alkalis, and moisture, combined with scratch resistance, suits environments with routine chemical exposure and frequent handling.
- Long Pass Filters: Germanium windows transmit wavelengths above 2 µm, functioning as long pass filters in IR and thermal imaging applications.
- Rugged Environments: Hardness and chemical resistance suit germanium windows to mechanically demanding environments within their stable operating temperature range.
Germanium windows
Avantier Custom Germanium Windows
Avantier designs and manufactures stock and custom germanium windows for your precision application, with the capabilities to accommodate and tailor dimensions, coatings, and tolerances for mission-specific systems. Built for thermal imaging, aerospace, and defense-grade environments, let’s talk about your mission requirements and begin designing your custom germanium window solution.
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