Coated Filters

Coated Filters are based on Thin Film Interference

Walter H. Geffcken created the first interference filters using dielectric coatings in 1939. Thin-film interference occurs when light waves reflected off boundaries between thin films of materials with different refractive indices interfere with one another. In this process the intensity of the resulting light wave can either be enhanced (constructive interference) or attenuated (destructive interference). When the film thickness is an odd multiple of one quarter-wavelength of the light wave, the reflected waves from both surfaces interfere destructively. As the wave can no longer be reflected, it is completely transmitted through the thin film. When the film thickness is a multiple of a half-wavelength of the light, the two reflected waves interfere constructively, enhancing the reflection and attenuating the transmission.

We produce many different types of coatings. Challenge us with your requirements!

  • AR Coating (single layer)
    Reduces the reflectance of a specific wavelength and maximises the transmittance by using a single layer coating. It can also be used as surface protection.

  • AR Coating (multilayer)
    A multilayer AR coating is used to limit the reflectance over a wide wavelength range as much as possible and maximise the transmittance. It can also be used as surface protection.

  • Band Pass Filter
    A filter that transmits only one specific wavelength band and suppresses all other wavelengths.
  • UV / IR Cut Filter
    A filter that transmits the visible wavelength range and does not pass the ultraviolet and near infrared wavelength range.
  • Dichroic Filter
    A filter that efficiently transmits cyan, magenta, and yellow, which are the three primary colours of blue, green, and red, or their complementary colours.
  • Notch Filter
    A filter that attenuates light of a specific wavelength to a very low level and transmits light of other wavelengths.
  • ND Filter
    A neutral density filter features flat transmittance over a wide wavelength range at specified levels.
  • Mirror Coating
    A highly reflective mirror made by metal coatings such as aluminium on a clear substrate.
  • Water Repellent / Oil Repellent Coating
    A coating which prevents water, dirt and oil etc. to stick to an optical surface.
  • Antistatic Coating
    A coating that prevents dust from attaching to an optical surface.