Surface Coating / Alfa Chemistry

Dielectric Mirror Coating


A dielectric coating is a single or several thin layers of submicron transparent dielectric material put on a substrate that modifies the reflective characteristics of the substrate by reflecting light. For high reflectivity or particular wavelength options, a single dielectric coating is frequently insufficient. To get the desired spectral qualities, numerous coatings must be stacked. Alternating thin film coatings of high and low refractive index dielectrics are placed on an optical substrate with high optical reflectivity to create dielectric mirrors.

Alfa Chemistry can supply you with dielectric coatings made up of thin layers of non-metallic materials to support your optical applications in the UV to IR wavelength range. To satisfy your individual application needs, we may additionally tailor the coating design for your substrate.

Applications and Benefits of Dielectric Mirror Coating

Dielectric coatings, unlike metallic coatings, use optical interference to change the reflectance of the coating surface using low-absorption materials. The reflectance of an optical surface can be adjusted from near zero to near 100 percent using optical interference coatings, but only at specified wavelengths or wavelength ranges.

Applications and Benefits of Dielectric Mirror CoatingFig 1. (a) Light reflected directly from a thin film (oil, soap) interferes with secondary reflections that may be in-phase or out-of-phase. (b) Dielectric reflector, also known as Bragg reflector.

In the UV to IR wavelength region, Alfa Chemistry's typical dielectric mirror coating delivers high broadband reflectivity. In addition, the metal-free dielectric layer transmits infrared light well. Another plus is their outstanding thermal stability. Highly reflecting laser mirrors, transmission output couplers, dichroic mirrors, different filters, heat reflectors, solar cell coverings, and thin film polarizers are all possible applications.

Alfa Chemistry Customized Optical Coating

Alfa Chemistry manufactures dielectric mirror coatings for optical substrates including fused silica, precision glass, BK-7, gradient index glass, ultra-thin wafers, low refractive index glass, and more. To provide consistent performance under difficult temperature and humidity conditions, we use ion beam sputtering deposition to build dense dielectric film coatings.

Our design team will collaborate with you to create a dielectric mirror coating that satisfies your requirements and has higher than 99.5 percent reflectivity in the wavelength range you specify. Alfa Chemistry also helps deposit dielectric materials such as silicon dioxide, aluminum oxide, magnesium fluoride, cerium fluoride, tantalum oxide, hafnium oxide, titanium dioxide, zirconium oxide on your substrates.

Customized Optical Coating

We provide a variety of dielectric mirror coatings, including but not limited to:

  • Anti-Reflection (AR) coatings, including single layer MgF2 coatings, V-coatings, and broadband AR coatings.
  • Laser protection film coatings: They're made to endure larger levels of energy than traditional film designs.
  • Three-way color filter film coating: It divides or recombines incident light into three different wavelength bands of red, green, and blue.
  • Ultraviolet filter film coating: It used to work in the shorter wavelength range of the visible spectrum, from the edge to 180nm.
  • Dichroic filter coating: Its job is to separate the incident light into different wavelength bands. It achieves color or wavelength separation with more precision than traditional filters.
  • Short/long wavelength pass filter coatings: They're utilized to make a wavelength-selective filter that can work in a range of wavelengths from ultraviolet to far-infrared. The high rejection ratio blocks wavelengths shorter than the filter transition point, whereas wavelengths longer than the transition point are transmitted.
  • Filter coatings: Bandpass filters let only a certain range of wavelengths pass through while blocking wavelengths outside the transmission region with a high blocking ratio. Bandstop filters block a certain wavelength range at a high blocking rate while transmitting wavelength ranges on both sides of the blocking zone.

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