High Reflection Coatings or High Reflective Coatings are thin films designed to increase the amount of light reflected from a surface, with the intention to minimize unwanted effects like transmission, absorption, and scatter. HR coatings are crucial in applications like mirrors, beam splitters, and laser cavities, where maximum reflectivities are needed to control or direct light with high efficiencies.
High reflection coatings can be categorized into two major types: dielectric HR coatings and metallic HR coatings. Dielectric HR coatings and High reflection coatings composed of metal (such as silver, gold, and aluminum) are designed based on two entirely different principles and hence have distinct advantages and drawbacks.
Dielectric HR coatings consist of numerous layers of thin films of a pair of different oxide materials, one with low refractive index (such as silica, SiO2), one with large refractive index ((such as titanium dioxide, TiO2), the layers are alternately stacked to form the dielectric coating. The thickness of each layer is meticulously engineered in correspondence with the design wavelength so that constructive interference is achieved between the reflected beams to maximize reflection. Via precise calculation of the the thicknesses of each layer via computer software, and adding up numerous layers, the reflectivities can be increased to near 100%.
Comparatively speaking, dielectric high-reflective coatings can reach a higher limit of reflectivities than would be possible in the case of metallic coatings. However, the design principle-based interference determined that dielectric HR coating is more sensitive to wavelength shifts and angles of incidence in its nature. At large AOIs, the reflection of HR dielectric coatings also became related to polarization. Metallic high-reflective coatings cater to wider wavelength ranges and AOI variations, and exhibit weaker chromatic dispersion, although with a lower achievable reflectance. Absorption of the incident light is another problem for metallic coatings, which makes them unsuitable for high-power applications.
Hangzhou Shalom EO offers custom optical coatings, this page specializes in our high-reflection dielectric coatings. Shalom EO has professional experience in customizing dielectric HR coatings with reflectivities maintained above the highest standards.
Shalom EO is capable of designing and tailoring dielectric HR coatings of miscellaneous types to suit your demand. We specialize in the custom coating service of Broadband HR (BBHR) Dielectric Coatings, Narrowband HR (NBHR) Dielectric Coatings, and Laser Line HR Coatings, including Single/Dual/Multiple Wavelength HR Coatings.
With cutting-edge computer modeling and designing techniques, numerous layers with computed thicknesses can be stacked up to achieve ultra-high, near 100% reflectivities.
Besides, Shalom EO also provides low GDD dielectric coating services for ultrafast and femtosecond lasers. With up-to-date metrological equipment like Ultrafast Innovations GOBI white light interferometer, the ultrafast optical coatings maintain optimal performance by minimizing temporal distortions, thereby preserving pulse fidelity.
