Germanium Glass for Infrared Optics: High Performance for Thermal Imaging & IR Applications
Germanium glass is a high-refractive-index infrared material widely used in thermal imaging, IR sensors, and spectroscopy systems. It offers excellent transmission in the mid-IR range (2–14 μm), making it ideal for lenses and windows in high-performance optical systems.
At Bote Optics, we offer precision-crafted germanium glass lenses, windows, and custom components tailored to your application needs.
What Is Germanium Glass?
Germanium glass refers to optical-grade germanium (Ge), a semiconductor material known for its superior transmission in the infrared spectrum. Unlike standard glass, germanium is opaque to visible light but transparent from 2 to 14 microns.
Key features:
- Excellent IR transmission
- High refractive index (~4.0)
- Chemically inert and stable
- Ideal for rugged environments
Germanium Glass Properties
| Property | Value |
|---|---|
| Transmission Range | 2–14 µm |
| Refractive Index (10.6 µm) | ~4.002 |
| Density | 5.33 g/cm³ |
| Hardness (Knoop) | 780 |
| Thermal Conductivity | 59 W/(m·K) |
| Melting Point | 938.3°C |
| Crystal Structure | Diamond cubic |
| Toxicity | Non-toxic when handled properly |
Note: Germanium is not recommended for environments above 100°C due to changes in its transmission properties at elevated temperatures.
Germanium Transmission Spectrum
Germanium transmits efficiently in the mid-infrared, especially in the 8–12 µm range, which is crucial for thermal imaging and FLIR systems.
(Insert suggestion: Graph showing Germanium transmission from 2 µm to 14 µm)
✅ Transmission >90% between 8 µm and 12 µm (uncoated)
✅ Anti-reflective coatings can improve overall system throughput
Germanium Glass Lenses
Germanium lenses are widely used in:
- Thermal cameras
- Gas detection systems
- Military optics
- Industrial temperature measurement
Available types:
| Lens Type | Features |
|---|---|
| Plano-Convex Lens | Focus IR light to a point |
| Meniscus Lens | Minimized spherical aberration |
| Aspheric Lens | Enhanced image quality, compact designs |
| Ball Lens | Fiber coupling or beam focusing |
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Custom lenses available with:
- Focal lengths from 10 mm to 300 mm
- Surface accuracy up to λ/10
- DLC or AR coatings
Germanium Lens for Thermal Camera
Germanium is the material of choice for thermal imaging lenses. Why?
- Transparent in LWIR (8–14 µm), which matches thermal emissions from people and objects
- Durable and stable in harsh environments
- Used in handheld thermal cameras, drones, night vision systems
We offer custom lens assemblies for OEM thermal systems with optimized coatings and housing integration.
Germanium Glass Windows
Germanium windows are used as protective barriers in IR systems, ensuring high transmission and mechanical protection.
Applications include:
- IR sensors
- Environmental monitoring
- Aerospace systems
- Gas analyzers
| Window Diameter | Thickness | Transmission (Uncoated) |
|---|---|---|
| 25.4 mm | 2 mm | >90% @ 10.6 µm |
| 50.8 mm | 3 mm | >88% @ 10.6 µm |
Custom sizes and DLC (diamond-like carbon) or AR coatings available for durability and improved performance.
Germanium Optics Applications
| Industry | Germanium Component Use |
|---|---|
| Defense & Military | Thermal scopes, surveillance optics |
| Industrial Automation | Non-contact temperature sensing |
| Medical Diagnostics | IR spectroscopy for tissue analysis |
| Environmental Sensing | Gas detection via FTIR |
| Aerospace | Infrared earth observation |
Germanium Coatings
Because of germanium’s high refractive index, uncoated surfaces reflect nearly 36% of incident light per face. Coatings are essential.
Common coatings:
- AR Coating (8–12 µm): Reduces reflection, boosts throughput
- DLC Coating: Scratch-resistant, ideal for outdoor use
- Broadband Coating: 3–5 µm or 8–14 µm ranges
Germanium Glass Price
The price of germanium glass components depends on:
- Diameter and thickness
- Coating type
- Quantity and surface accuracy
Estimated Price Range:
| Component Type | Size | Approx. Price (USD) |
|---|---|---|
| Germanium Window | Ø25.4 x 2 mm | $50 – $80 |
| Germanium Plano Lens | Ø25.4 mm, FL = 50 mm | $70 – $120 |
| AR/DLC Coated Window | Ø25.4 x 2 mm | $90 – $130 |
| Custom Lens Assembly | Depends on spec | Contact for quote |
Bulk pricing and OEM solutions available.
Cleaning & Handling of Germanium Glass
- Clean using isopropyl alcohol and lint-free wipes
- Avoid sudden temperature changes
- Handle with gloves to prevent contamination
- Store in dry, room-temperature environment
Caution: Although non-toxic, germanium dust should not be inhaled during machining or grinding processes.
Why Choose Bote Optics for Germanium Optics?
- ✅ ISO-certified optical manufacturing
- ✅ Advanced CNC and polishing equipment
- ✅ Strict surface quality inspection (scratch-dig, interferometry)
- ✅ Fast prototyping and stable mass production
- ✅ Worldwide delivery & responsive support
Contact Us for Germanium Glass Solutions
Whether you need germanium glass lenses, windows, or complete IR optical assemblies, we deliver custom solutions for precision infrared optics. Request a quote or consult with our optical engineers today.