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Examples of Optical Coatings

• An anti reflective coating reduces unwanted reflection. For instance, a standard uncoated glass component will reflect about 4% of incident light. The same glass component with an AR coating tailored for the wavelength of light being transmitted might reflect less than 0.1% of incident light. We offer a variety of different dielectric anti reflective coatings, including both broadband and narrow band options. One versatile and hardwearing option is magnesium fluoride, which comes in both single-film and multiple layer options.
  
  
• A reflective coating causes the surface to which it is applied to reflect all or some of the light which hits it. Consider again the uncoated glass optic with 4% reflection. An aluminum coating will cause the same optic to reflect 88092% of visible light. Silver coatings reflect 95-99% into the far infrared regions (reflection will be lower in the UV and some parts of the visible spectrum), and an appropriately chosen dielectric coating could increase reflectivity to 99.9%. Dielectric mirror coatings are often formed of two discrete repeating layers, one with a high index (for instance, ZnS or TiO2), and one with a low index (think MgF or SiO2).
  
  
• A polarizing coating is formed of a very thin film of a birefringent materials. Under certain circumstances, a polarizing coating on a lens or optical window can be used to replace polarizing prisms in an optical assembly.
  
  
• A transparent conductive coating is a special type of coating the combines high transmission of visible light and electrical conductivity. The resistivity of a transparent conductive coating is specified in ohms per square, and may be anywhere from 4-1,000 ohms per square depending on application.

Shanghai Optics can provide all types of anti-reflective, high reflective, and partial reflective coatings. We produce a wide variety of coatings from a single layer of anti-reflective coating to complex multi-layer dielectric stacks. Types of dielectric coatings are BBAR, V-coatings, dual wavelength coatings, and sharp cut-on and cut-off filters.