Measurement and Monitoring Method of Film Thickness of Modern Vacuum Coating Machine

The most direct coating control method is the Quartz Crystal Microbalance Method (QCM), which can directly drive the evaporation source, and cycle the baffle through PID control to maintain the evaporation rate. As long as the instrument is connected to the system control software, it can control the entire coating process. But the accuracy of (QCM) is limited, in part because it monitors the quality of the coating being deposited rather than its optical thickness.

Also, while the QCM is very stable at lower temperatures, it becomes very temperature sensitive at higher temperatures. During prolonged heating, it is difficult to prevent the sensor from falling into this sensitive area, causing significant errors in the film.

Optical monitoring is the preferred method of monitoring for high-precision coatings because it allows more precise control of layer thickness (if used properly). The improvement in accuracy stems from many factors, but the most fundamental reason is the monitoring of optical thickness.

The OPTIMAL SWA-I-05 single-wavelength optical monitoring system adopts indirect measurement and control, combined with advanced optical monitoring software developed by Dr. Wang, to effectively improve the theory and method of optical response sensitivity to film thickness changes to reduce the ultimate error, providing feedback or transmission choice of modes and a wide range of monitoring wavelengths. It is especially suitable for coating monitoring of various film thicknesses including irregular film monitoring.