Dontech’s optical filters are produced with one or more layers of substrates to create the desired optical and physical properties. Optical laminations are only suitable for the visible and part of the IR spectrum. Within this suitable spectrum, several different substrates can be used together to achieve an optimum configuration and enhanced properties. Dontech’s optical substrates are available with functional coatings and features specific to the application requirements.
Glass, plastics, and crystalline materials are the most common substrate families used in the fabrication of optical filters. There are many types or grades of material within each family. Dontech optically coats and converts a variety of optical substrates as either rigid substrates or flexible films for display, touchscreen, and structural transparency applications.
Plastics are a common substrate for visible spectrum applications. They are very common components to a broad range of touchscreens and display overlays. Most plastics are typically chemically and mechanically soft or they typically employ some form of thick film coatings (e.g., hard coating) to improve their performance. Plastics can be extruded, cast, lapped, and polished, laminated, thermally formed, and injection molded.
They are easier to machine and laminate, lighter in weight, and more impact resistant than other standard optical substrates which makes them desirable for many industrial, medical, and military portable applications. Plastics also are very conducive to roll-to-roll processing which makes them the most common film-based optical product. The most common rigid optical plastics are polycarbonate and acrylic sheet materials and for film products, PET and TAC. Standard available plastics include:
Different types of glass are a common substrate for visible through near-IR spectrum applications. Glass can be fabricated to very high optical properties, can be fabricated to very tight mechanical tolerances, it is inherently hard, and it has a broad thermal range which helps make it an excellent candidate for the highest performing thin film coatings. It is the most common substrate in the demanding environments of cockpit display optical filters and some precision optics.
Glass substrates can be chemically strengthened, annealed, and tempered to improve impact resistance and flexural strength. Glass substrates have better optical properties and thermal range in comparison to most plastics. Glass can be surface etched to provide antiglare properties, thin film coated, and laminated to improve functional properties. Standard available glass substrates include:
Different types of crystalline substrates are the only option as you get deeper into IR wavelengths. They are the primary family for creating precision optics (e.g., transparent heater for a laser targeting system) for visible through the near IR spectrum applications. They are typically fabricated to very high optical specifications and mechanical tolerances. They are a very good candidate for high performance thin film coatings.
Crystalline substrates are almost always lapped, polished, and diamond turned to provide customized properties including plano, aspherical, and spherical optics. They are typically machined to very tight tolerances. They are almost always thin film coated and they can be micro-embossed, etched, or treated to provide superior properties in applications with spectrum ranging from the visible through 25 microns in the infrared. Each crystalline substrate has very different useful spectrums. Some are mechanically very hard. Standard available crystalline substrates include:
Dontech has extensive engineering and technical support resources that can assist you with your substrate selection. Our technical staff have diverse backgrounds relevant to high-performance display and precision optics markets. For many of our top customers, we function as an extension of their engineering departments, supporting projects from concept to final system delivery. We will integrate our optical filters (OFED) and other enhancing components into touchscreens (DTS), displays (DES) and systems to the level that is needed by our customers.