Choosing a Chamber
In the last 15-20 years the equipment used to deposit optical thin film coatings has changed dramatically. In years past, a typical coating machine was completely manual or semi-automatic at best and required a highly skilled operator to produce consistent results.
Today, a top quality optical coating machine blends an eclectic collection of smart subsystems into a fully automated deposition system. These subsystems are usually supervised by a number of microprocessors, which are then integrated into a local area network (LAN), which in turn is tied to an overall factory automation system. The increasing sophistication of the user translates to ever more demanding specifications for system performance; it is not unusual for customers to buy process expertise along with the machine. In this article we examine the components and subsystems which are available for today’s optical coating systems, and we look at how process issues tend to dictate component selection and chamber configuration. Although other technologies are becoming popular, we will focus on physical evaporation as it is still the most widely used and versatile of the available technologies.