Coating Material Filter Element​

Physical Vapor Deposition (PVD) is the process in which a solid material is heated and passes directly from a solid to a gaseous state (sublimation) and then returns to a solid state as it condenses on a given substrate, typically under vacuum.

The traditional approach is to use a resistive heating element to evaporate the coating material. Thermally-prepared coatings have been an industry mainstay for over 25 years.

To protect and preserve these filters for long-term stability, they are typically laminated with a coverslip after preparation. While less common today, they still offer several advantages over surface coatings.

Because the range of refractive indices is much wider among these materials than among oxides, a much thinner coating stack can achieve similar optical results.

This reduces substrate stress and minimises wavefront distortion — particularly important as target wavelengths move into the infrared, where thicker layers would otherwise be required.

These optical filters offer deep out-of-band blocking with low residual stress and stable spectral performance.