Chalcogenide glass (IRG materials such as IRG24 and IRG26) is increasingly used in modern infrared optical systems due to its lightweight properties and cost advantages over traditional materials like Germanium. It is widely adopted in LWIR (8–12 µm) applications, particularly for compact and high-volume thermal imaging systems.
However, chalcogenide materials are relatively soft and sensitive to environmental exposure. To enhance durability and extend operational lifetime, Diamond-Like Carbon (DLC) coating is commonly applied as a protective layer.
What is DLC Coating?
DLC (Diamond-Like Carbon) is a thin-film coating with properties similar to diamond, including high hardness, chemical resistance, and low friction. In infrared optics, DLC is typically applied as the outermost protective layer, often combined with anti-reflection (AR) coatings to balance durability and transmission.
Why Apply DLC Coating on Chalcogenide Glass?
Chalcogenide glass offers many advantages, but its mechanical properties require protection for real-world use.
- Improved Surface Hardness – Protects soft chalcogenide substrates
- Abrasion Resistance – Reduces scratches during handling and operation
- Hydrophobic Surface – Minimizes moisture and contamination effects
- Enhanced Environmental Stability – Withstands humidity, dust, and harsh conditions
- Extended Product Lifetime – Enables reliable field deployment
DLC transforms chalcogenide optics from lab-use components into robust field-ready solutions.
Technical Considerations
Applying DLC coating on chalcogenide glass is more technically demanding compared to Germanium.
Key Challenges
- Adhesion Control – Requires optimized surface preparation and bonding layers
- Stress Management – DLC films have intrinsic stress that must be controlled
- Thermal Sensitivity – Chalcogenide materials require low-temperature deposition
- Surface Quality Sensitivity – Any defects are replicated after coating
Typical Performance
- Wavelength Range: 8–12 µm (LWIR)
- Transmission (Tavg): ~90–93% (DLC + AR combined)
- Substrates: IRG24, IRG26, and other chalcogenide variants
Applications
DLC-coated chalcogenide optics are widely used in:
- Compact thermal imaging cameras
- Drone-mounted infrared systems
- Automotive night vision and ADAS
- Portable inspection and monitoring devices
- Consumer thermal imaging products
Why Choose Shape Optics Technologies
At Shape Optics Technologies Pte Ltd, we understand the complexities of coating chalcogenide materials.
We tailor coating solutions based on your application requirements, environmental conditions, and performance targets.
Conclusion
DLC coating is essential for improving the durability and usability of chalcogenide glass in infrared optics. While the process requires careful control of adhesion, stress, and deposition conditions, it enables IRG materials to perform reliably in demanding environments.
With the right expertise, DLC-coated chalcogenide optics offer an excellent balance of performance, cost, and weight.
Contact us today to discuss your requirements. Our team is ready to support your project with customized optical and coating solutions.