BaWhat Is a Germanium Window?
A Germanium Window is an optical component made from high-purity germanium crystal, used in infrared (IR) systems for imaging, sensing, and spectroscopy. Germanium is ideal for IR windows because of its high refractive index, excellent thermal stability, and broad transmission range (2–16 µm).
At Bote Optical, we manufacture custom germanium windows with precise dimensions, surface flatness, and AR/DLC coatings. Our products serve applications in defense, aerospace, medical, and industrial automation.
🔬 Germanium Optical Properties
| Parameter | Typical Value |
|---|---|
| Chemical Symbol | Ge |
| Crystal Structure | Diamond cubic |
| Transmission Range | 2 – 16 µm |
| Peak Transmission (Uncoated) | >45% (between 3 – 12 µm) |
| Refractive Index (at 10.6 µm) | ~4.0 |
| Density | 5.33 g/cm³ |
| Hardness (Knoop) | ~780 |
| Absorption Coefficient | Low in IR, high in visible |
| Transparency | Opaque to visible light |
| Operating Temperature | Up to 100°C (recommended) |
Germanium has zero transmission below 2 μm, making it entirely opaque in the visible spectrum. However, its IR performance is unmatched, especially in thermal imaging and long-wave IR systems (LWIR).
🧪 What Is Germanium and Why the Name?
Germanium is a metalloid element (atomic number 32) discovered in 1886 by German chemist Clemens Winkler. He named it “Germanium” after his homeland, Germany. Though it resembles tin or silicon, germanium stands out for its semiconductor and optical characteristics, especially in the infrared range.
🪟 Germanium Window Transmission
Uncoated germanium has moderate transmission (~45–55%) in the 3–12 µm range. With AR coatings, transmission can exceed >90%. For high durability, especially in outdoor or military environments, DLC (diamond-like carbon) coatings are often applied.
💡 Applications of Germanium Windows
- Thermal imaging cameras (LWIR)
- FLIR and night vision systems
- Gas sensing and IR spectroscopy
- Aerospace and military sensors
- CO₂ laser beam delivery (with ZnSe lenses)
- Environmental monitoring
🛠️ Bote’s Custom Manufacturing Capabilities
As an established optical component factory with facilities in Singapore and Nanjing, Bote supports a wide range of Germanium Window specifications, including:
| Specification | Range |
|---|---|
| Diameter | 5 mm – 100 mm |
| Thickness | 0.5 mm – 25 mm |
| Surface Flatness | λ/2 to λ/10 |
| Surface Quality | 60-40 to 20-10 (MIL-PRF-13830B) |
| Bevel Options | Protective or custom bevel |
| Coating Types | AR (8–12 µm), DLC, or dual coatings |
📦 All products include full inspection reports and are available for global shipping.
💰 Germanium Window Price Guide
The price of germanium windows depends on size, coating, quantity, and surface specifications.
| Size (Diameter x Thickness) | Coating | Estimated Price (USD) |
|---|---|---|
| 25.4 mm × 2 mm | Uncoated | $40 – $70 |
| 25.4 mm × 2 mm | AR Coated | $60 – $95 |
| 50.8 mm × 5 mm | DLC + AR Coated | $120 – $180 |
🔗 Request a free quote today via [email protected].
📄 Germanium MSDS and Safety
Germanium is considered safe in solid optical form. However, its dust or vaporized particles during grinding or coating can be hazardous.
- Always wear protective gear
- Ensure proper ventilation
- Dispose of waste according to local regulations
📥 You can request a copy of our Germanium Window MSDS via contact form.
❓ FAQs about Germanium Windows
Q1: What is the refractive index of Germanium?
A: Approximately 4.0 at 10.6 µm, one of the highest among IR materials. This makes it excellent for compact lens systems, though anti-reflection coatings are necessary to reduce surface reflection loss.
Q2: What is the germanium absorption coefficient?
A: Germanium exhibits low absorption in the 2–14 µm range. Beyond 16 µm or under high temperatures, absorption increases. Always consider thermal effects when used in high-power IR systems.
Q3: Is Germanium better than ZnSe or CaF₂?
A: Depends on the application:
- ZnSe: Higher transmission, lower refractive index, more fragile
- CaF₂: Broader spectral range, but softer and more hygroscopic
- Ge: Best for compact, rugged IR designs needing high thermal resistance
Q4: What is a germanium sheet?
A: A germanium sheet is a flat, unshaped slab of raw or semi-finished germanium, used as a precursor for optics or semiconductors. Bote provides both finished optical windows and raw cut blanks upon request.
🌍 Why Choose Bote for Germanium Windows?
- ✅ In-house fabrication & coating lines
- ✅ Singapore-based customer support for global buyers
- ✅ Custom specs for defense, medical, and OEMs
- ✅ Fast response and engineering assistance
- ✅ Competitive pricing & small batch flexibility
📞 Contact Us or email [email protected] for immediate technical support or a custom quote.
- Inspection Equipment List and Metrology of Bote Optics
- Introduction of BOTE Key Equipment
- Catalog of Precision Optics
- Catalog of Imaging Optics
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