How is Optical Thin Film Coating Applied?

If you are anything like most people, you probably don’t spend a lot of time thinking about optical thin film coating. In fact, if you are like the majority of people in America, you might not even understand exactly what optical thin film is. Luckily, we here at Newport Thin Film Laboratory know all about optical thin film coatings and, in today’s post, we are going to go over some of the different application methods utilized to secure these films to the surfaces of objects. We hope that by the end of this blog you have a better understanding of how optical thin film is applied to various surfaces and why these film coatings are needed at all. Continue reading below to learn more.

Thin Film is Used by a Wide Range of Industries

Thin film is a layer of material that can range from fractions of a nanometer to several micrometers in thickness. While thin film coating has been used for mirrors for years, advances in the thin film industry during the 20th century have enabled these materials to be used for a wide range of technological areas such as LEDs, electronic semiconductors, and optical coatings. Below, we have listed a few of the methods used to apply optical thin film to these devices.

• Electron Beam: The most widely used form of optical thin film application, electron beam technology places the source material in an electron beam gun. The gun then produces a stream of electrons that are guided by a series of electromagnets onto the coating material. Once the beam heats the material to the appropriate temperature, it evaporates and moves to the top of the chamber where it is then deposited onto the substrates. To increase uniformity, the substrates are rotated in the chamber to ensure that the surface is coated evenly and, during the end of the process, an ion gun beams is added and directed towards the substrates to increase the density of the coating. Electron beam systems are the most popular application method because the systems are versatile and can be reconfigured quickly, allowing the user to easily swap out the types of coating material. Additionally, this application system uses a relatively low amount of material for each run, an advantage when coating with expensive materials.

• Low Pressure Chemical Vapor Deposition: LPCVD application techniques utilize a thermally driven chemical reaction process where the starting materials are metallorganic liquids referred to as precursors. These precursors are then delivered to an evaporation manifold, vaporized, and then a flow of nitrogen is introduced to the system that carries the vapor into the reaction chamber. The heat from the reaction chamber, which is kept at around 500 degrees Celsius, breaks the precursor’s chemical bonds causing the resulting metal oxides to condense onto the surfaces of the chamber. A nitrogen flow is then introduced to the camber and sweeps out any waste products or unreacted material that are left over from the process. The LPCVD process of application is advantageous because it coats areas uniformly, meaning that it is an excellent choice for coating optics with complex shapes.

Join us again next time as we continue to cover some of the application methods used to deposit optical thin film coatings on objects. If you would like to learn more about optical thin film coating or would simply like to learn more about what we do at Newport Thin Film Laboratory, visit our website today. We strive to deliver the best thin film coating solutions available and we are positive that we can handle any job that you may have.