The ever expanding role of optical thin film coatings in today's industrial, military and defense applications has lead to huge advances in the development of thin film technologies. These improvements change the way we can reflect, filter and transmit light and impacts how light is moved through an optical system. Optiforms is on the cutting edge of optical thin film development and is committed to improving optical thin film technologies.
Common uses for optical coatings include motion picture projection, lenses, filters, mirrors, and of course Optiforms nickel electroformed reflectors. Coatings can be designed to meet the specific requirements of an optical system. These requirements can include maximizing the efficiency of an optical surface by changing how the surface reflects and transmits light. When designers are developing optical systems most of their time should be spent developing the layout of the prisms, lenses, mirrors and other components. Optical thin film coatings can then be applied to the components to enhance the efficiency of the optical system and maximize system performance.
Thin film coatings can be classified as single layer or multi-layer coatings and can be further classified as metallic, dielectric or hybrid coatings. Optiforms metallic coatings typically consist of gold, silver, aluminum or rhodium. Metallic coatings are chosen based on the requirements of a specific optical system as each of these metals has different performance characteristics at different wavelengths. Aluminum and silver can be vacuum deposited were rhodium is typically electrodeposited. Gold can be either vacuum or electrodeposited. It is common to produce reflective surfaces with metallic optical thin films. Hybrid coatings are multi-layer coatings consist of a metallic base coat with dielectric overcoats. These overcoats change the characteristics of the base metal and can be applied to improve handling characteristics. Dielectric coatings are very common and consist of various non-conductive oxides including SiO2 and TiO2. The common uses for dielectric coatings include movie projection and camera optics. Optiforms dielectric coatings can contain as many as a 50 layers, designed to improve certain optical characteristics.
Coatings are classified as reflective or antireflective and broad banded or narrow banded. The layers in these coatings are very thin, typically 10-20 millionths of an inch thick. The layers are designed to be 1/4 or 1/2 the wavelength of light. A reflective coating can reflect nearly 99.9% of light if designed correctly and anti reflection (AR) coatings can achieve extremely low reflectivity, as low as 0.1%. An AR layer in an optical system can improve system throughput and reduce image "ghosting" by reducing reflected light.
Optical coatings are designed to perform under specific conditions and can be affected by wavelength, angle of incidence and environmental factors such as temperature or humidity. In order to achieve maximum performance for the lifetime of your optical coating it is best to consider the specific conditions that will affect your system in the design stages. Optiforms technical staff is available to assist you with the selection of the correct optical coating for your application.
Vacuum deposition is a process where substrates are placed in a vacuum chamber capable of achieving vacuum of 10-6 torr or better. The substrates sweep through the chamber in a planetary motion to ensure even distribution of material. At the bottom of the chamber is an electron beam gun that vaporizes the material to be deposited. The vaporized material condenses onto the substrates surface and creates a thin film. Optiforms has many different sized vacuum chambers; the chamber selection is chosen based on part quantity and type of coating to maximize performance and cost efficiency
Many of Optiforms optical thin films are produced by vacuum deposition. Most vacuum coating companies can only coat flat glass. Optiforms can coat flat glass, but we specialize in coating the structures that other companies cannot. Coating deep-dish elliptical and parabolic reflectors is our specialty. Optiforms can coat reflectors up to 30 inches in diameter.
Considerations when selecting an optical thin film coating
There are some critical steps you should use when selecting an optical thin film coating in order to maximize your optical systems performance. When contacting Optiforms it helps to have the following information available.
