Diamond-Like Carbon (DLC) coatings have been around since the late 1970s. These coatings are used in machining and automotive applications because of their exceptional durability, high hardness, low coefficient of friction and self-lubricating properties. Not only did the coating reduce wear on frictional components, it also increased the efficiency of motors. The same properties that make DLC an excellent coating for frictional applications also make it a superior coating for optical and electrical applications.
However, there are four common issues with the quality of a DLC coating on IR optics:
- Small defects called pinholes
- Non-uniform coating thickness
- Residual stress between the coating and the base material
- Poor coating adhesion
One source of these defects is the design of the DLC deposition process and the chamber configuration. Plasma Enhanced Chemical Vapor Deposition (PE-CVD) has emerged as a preferred process for addressing these flaws.