An optical thin film consists of one or more layers of dielectric material or metal, with individual layer thicknesses typically ranging from a few nanometers to several microns. In the case of dielectrics, these modify the reflectance and transmittance characteristics of the underlying substrate through the mechanism of optical interference, based on the exact thickness and index of refraction of each layer. Metallic coatings reflect and absorb light based on their bulk material properties (although metallic layers can also be incorporated into multi-layer dielectric coatings).

Producing a practical coating requires tight control of deposition so that the desired sequence, uniformity, material thicknesses and indices of refraction are achieved. Good adhesion is also important if the optic is to be mechanically durable, as is the ability to retain consistent properties in the presence of temperature and humidity swings for those applications requiring environmental stability. Additionally, economics dictate the use of production equipment that allows for large batch sizes and/or short cycle times.

Every coating fabrication method in use has its place, and there is no one approach that is best for every application. For example, coating high laser damage threshold optics for military lasers requires a different approach than making optics for high volume telecommunications use, or a low cost, consumer, virtual reality headset.

DSI employs MicroDyn®, which is a form of magnetron sputtering. The MicroDyn is capable of coating a large amount of substrate material in a batch process. This enables us to deliver cost-effective, high-performance coatings for a very broad range of applications.

The information here briefly explains the deposition technique and summarizes the most important performance characteristics. It is intended to help customers make an informed decision when specifying and purchasing thin films.