Optical Coatings

Optical coatings are pivotal in the field of photonics, designed to alter the transmittance, reflectance, and polarization properties of an optical substrate. For example, an uncoated glass surface typically reflects about 4% of the incident light. With the application of an anti-reflection coating, this reflection can be reduced to less than 0.1%. On the other hand, by using a reflective dielectric coating, reflectivity can be amplified to surpass 99.99%. These coatings can range from a single layer of metallic thin film, such as aluminum or silver, to a complex composition of materials, which may include metal oxides and rare earth compounds. The efficacy of an optical coating hinges on the number and thickness of its layers, as well as the refractive index disparity among them.

At DayOptics, our expertise spans the spectrum of optical coatings, from fundamental anti-reflective layers to intricate high-reflective and partial-reflective configurations. Our offerings range from a single layer anti-reflective coating to complex multi-layer dielectric assemblies. To ensure superior quality, we use a variety of different methods to produce high quality optical coatings. Including Ion Beam Sputtering (IBS), Ion Assisted Deposition (IAD), and Magnetron Sputtering (MS) and Electron Beam Evaporation (EBE)

Both Ion Beam Sputtering and Ion Assisted Deposition stand out for delivering exceptional spectral performance, remarkable durability, and consistent repeatability. However, it's worth noting that these techniques, while delivering top-tier results, are more time-intensive and carry a higher cost. For those seeking a more economical approach, Electron Beam Evaporation (EBE) may be a cost-effective alternative.

Electron Beam Evaporation

Electron Beam Evaporation (EBE) represents the conventional technique within the realm of Physical Vapor Deposition (PVD). Thanks to its high evaporation rate and substantial capacity, it is the choice for keeping costs at a minimum. The coating process takes place within a heated (250°C) high vacuum chamber, utilizing an electron beam gun. Each electron gun emits a high-voltage electron beam that converges onto a water-cooled, rotating crucible containing the film material. This beam serves to liquefy and vaporize the material at an approximate temperature of 2000°C.

Ion Assisted Deposition

Ion-assisted deposition (IAD) builds upon the electron beam evaporation (EBE) coating deposition system, incorporating an additional plasma source. The plasma source imparts the kinetic energy required for the formation of the deposited film layer, leading to a denser microstructure that eliminates thermal drift. While IAD maintains a high evaporation rate for cost reduction purposes, it also offers reduced internal stress.

Magnetron Sputtering - MS

Magnetron sputtering (MS) employs magnetron plasma to sputter a metal layer onto a substrate, followed by oxygen ions within the plasma to oxidize the metal layer, resulting in the formation of a metal oxide. This technique produces very dense and hard layers.

Ion Beam Sputtering – IBS

Ion Beam Sputtering (IBS) is the most advanced of PVD technology, especially crucial in laser optics. The process involves sputtering layer material from a metal or oxide target, which subsequently gets deposited onto a vertically rotating substrate holder. In standard IBS machines, uniform layer distribution is generally confined to an area of approximately 300mm in diameter. IBS distinguishes itself as a "cold" deposition procedure, maintaining chamber temperatures below 150°C.

Custom Optical Coatings

The final properties of a dielectric coating are intrinsically linked to the materials chosen for the thin film layers, with their refractive index being of paramount significance. Adjusting the thickness of these layers or altering their count can profoundly modify the interference effects and, by extension, the overall function of the thin film coating. In the realm of precision coatings, it's imperative that the optical thickness of each layer is stringently controlled.

If you're seeking the perfect optical coating design tailored to your specific needs, look no further. The design will be influenced by factors such as the light's wavelength, the operational environment of the optic, and your budget. Boasting over 15 years of expertise in coating technologies, our design team is well-equipped to guide you in identifying the custom optical coatings that are optimal for your application.