1. DLC in optics Student talk Saara Hirvonen 5.12.2013

2. Contents Introduction DLC optical properties Optical applications Future trends Summary Saara Hirvonen

3. Introduction Typical DLC applications: wear resistance DLC films have amorphous structure –Properties can be adjusted Optical coatings are essential in advanced applications –Filtering of specific wavelengths –Reflection and deflection –Reflection reduction Saara Hirvonen

4. DLC optical properties Reflective index 2.0 –Good broad bandgap anti-reflection (BBAR) performance Optical transparency NIR-FIR Layer thickness optimized for specific wavelength 1,2 1) A. Grill. 1999. 2) Tydex. Saara Hirvonen

5. Optical applications IR optical systems coating with DLC –Anti-reflection –Resistance to abrasion, salts, acids, alkalis and oil 2,3 2) Tydex. 3) Jenoptik. 4) Reynard Corporation. Saara Hirvonen Military and marine windows Outdoor thermal cameras 4 3

6. Optical applications: IR antireflection coating Substrate materials –Ge, Si –ZnS, ZnSe, glass, ceramics, crystals, plastics 4 Spectral range depending on coating thickness –Wavelengths 3-5 µm and 8-12 µm Deposition with PECVD –Standard process for Ge and Si substrates 5 4) Reynard Corporation. 5) Leybolt Optics. Saara Hirvonen

7. Future trends – Coating improvement DLC single-layer coating –Stable structure –Spectral performance is limited at specific wavelength –Average reflectance 2,6 % for long-wavelength IR spectral range Hybrid-DLC –Antireflection properties improved with different layers –Reflectance of <0.15% –Multilayer coating enables broader working bandwidth 6,7 6) M. Degel & E. Gittler. 2013. 7) M. Gilo. 2013. Saara Hirvonen

8. Coating improvement: hybrid-DLC 1- 50 dielectric layers with PVD DLC with PECVD Fewer optical components needed 7 Saara Hirvonen

9. Summary DLC optical properties –Good BBAR performance –Optical transparency NIR-FIR IR optical systems coating –Anti-reflection –Environment resistance Hybrid-DLC –Multilayer coating enables broader working bandwidth Saara Hirvonen

10. Thank you! Questions?

11. References Properties 1) A. Grill. Electrical and optical properties of diamond-like carbon. Thin Solid Films. Vol:355-356. 1999. http://carbon.utsi.edu/downloads/AGrill_electrical_optical_dlc.pdf http://carbon.utsi.edu/downloads/AGrill_electrical_optical_dlc.pdf 2) Tydex. Hard Carbon Coating (DLC: "Diamond-Like Coating") http://www.tydexoptics.com/materials1/coatings/dlccoatings/ http://www.tydexoptics.com/materials1/coatings/dlccoatings/ IR coatings 3) Jenoptik. Diamond-Like-Carbon (DLC) Coatings. http://www.jenoptik.com/en-diamond-like-carbon-coatingshttp://www.jenoptik.com/en-diamond-like-carbon-coatings 4) Reynard Corporation. Diamond Like Coatings – ClearDLC. http://www.reynardcorp.com/cleardlc.htmlhttp://www.reynardcorp.com/cleardlc.html 5) Leybolt Optics. DLCcs - Diamond Like Carbon Coating System. http://www.leyboldoptics.com/optics/precision- optics/machines/dlccs/dlccs.htmlhttp://www.leyboldoptics.com/optics/precision- optics/machines/dlccs/dlccs.html Hybrid DLC 6) Michael Degel & Elvira Gittler. Multispectral Optical Coatings Are Tough, Versatile for IR Applications. Jenoptik Optical Systems GmbH. 2013. http://www.photonics.com/Article.aspx?AID=53225http://www.photonics.com/Article.aspx?AID=53225 7) Mordechai Gilo. Low-reflectance, durable coatings for infrared lenses. SPIE Newsroom. 2013. DOI: 10.1117/2.1201212.004581 http://spie.org/x91883.xmlhttp://spie.org/x91883.xml