INVESTIGATION OF THE EFFECT OF SAMPLE HEIGHT AND SURFACE CURVATURE ON THE ANTI-REFLECTION PROPERTIES OF DLC COATINGS ON Si SUBSTRATES USING PECVD TECHNOLOGY
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2025-10-15 |
| Journal | Journal of Science and Technique |
| Authors | Thi Kieu Trang |
Abstract
Section titled āAbstractāIn the field of security, thermal imaging devices are increasingly employed in surveillance systems and often operate under harsh environmental conditions. To ensure their durability and performance, protective diamond-like carbon (DLC) coatings are often deposited on the outer lens or protective lens. DLC films are highly attractive owing to their excellent wear resistance, high hardness, environmental stability, and infrared transparency within the spectral range of thermal imaging systems. In this study, DLC coatings were deposited using plasma-enhanced chemical vapor deposition (PECVD) with the Aegis DLC-PECVD system (Intlvac, Canada). A challenge in coating large optical components is that variations in plasma distribution can lead to film non-uniformity. We report experimental results on the deposition of anti-reflective DLC coatings on Si substrates for the mid-wave infrared spectral region (3-5 Āµm). The uniformity of the DLC layers was assessed through transmission spectroscopy of samples placed at different positions inside the deposition chamber. The results indicate that varying the sample height from 0 to 40 mm relative to the plasma electrode caused negligible changes in spectral shape, while the transmission intensity exhibited only a slight variation of ~1.6% for single-side DLC-coated samples. For samples placed at different tilt angles, the transmission peak shifted toward longer wavelengths, from 3.4 to 4 Āµm, corresponding to incident angles between 0Ā° and 50Ā°. These findings provide useful insights for optimizing sample holder design to improve the thickness uniformity and optical performance of DLC coatings on large thermal imaging lenses.