Anti-reflective (AR) coatings are optical coatings that decrease the amount of light reflected off a surface. Commonly applied to lenses, mirrors, or glass barriers, AR coatings are designed to maximize the throughput of light, while reducing hazards caused by reflections. This ability makes AR coatings an ideal solution for optical instruments, imaging devices, cameras, telescopes, eyeglasses, binoculars, and more.
To determine whether AR coatings are the best fit your needs, there are various factors to consider, including the number of optical elements, the substrate, and the application.
Number of Optical Elements
Uncoated reflective glass substrates can interfere with the passage of light through an optical system. Due to Fresnel reflection, 4% of transmitted light is lost at each interface of an uncoated glass substrate, resulting in only 92% total transmission of incident light. The reduced throughput and reflected light can simultaneously cause damage and reduce performance.
AR coatings increase throughput and stop the reflected light from causing damage. They are especially useful for systems containing multiple optical elements, as they allow for more efficient use of light.
The type of substrate will also play a role in determining whether an AR coating will be the most effective solution. At Evaporated Coatings, we offer AR coatings for the following substrates:
Glass AR coatings can target any wavelength spectrum ranging from 200nm to 2500nm. To ensure maximum transmission through a system, clients can specify their incident medium, wavelength range, angle of incidence, polarization needs, and the substrate index of refraction. Glass is frequently used in laser systems, which require AR coatings that can meet or exceed Laser Damage Threshold (LDT) minimums for the system.
Plastic and Molded Polymer
Many plastics and molded polymer substrates are vulnerable to heat damage, so they need particular AR coating processes in which the temperature doesn’t exceed 50°C. Low-temperature AR coatings can be applied to a wide variety of substrates, such as Kapton, polycarbonates, acrylics, and more. However, they typically operate within a slightly narrower range of frequency, from 300nm to 2000nm.
Fiber optic materials, including fiber arrays and ends, laser diodes, lenses, and more, utilize AR coatings to increase light transmission. These materials require a low-temperature anti-reflective coating process that reduces the risk of outgassing. To meet the needs of various applications, these AR coatings come in many designs, including L-Band, C-Band, dual wavelength, and more.
Crystals, Semiconductors, and Garnet
For these substrates, AR coatings are deposited with high energy, producing dense films with superior surface qualities and low optical loss. These AR coatings ensure a high resistance to laser damage, excellent surface qualities, and minimal spectral shift due to moisture exposure. AR coatings can be customized based on the sensitivity of the crystals, wafers, or semiconductor materials.
AR coatings solve a variety of issues across a diverse range of industries, including photography, optometry, solar energy, and more. When determining whether AR coatings are the right solution for your needs, it’s important to consider your intended application.
Common applications that benefit from AR coatings include:
- Displays. AR coatings on displays and screens allow for greater optical performance by minimizing glare and reflection. When outside light hits a screen, it causes glare. AR coatings can solve this problem.
- Camera Systems. Camera systems use AR coatings to reduce unwanted reflections and glare when used for imaging and telecommunications.
Types of AR Coatings
If you determine that your application can benefit from an AR coating, it is crucial to understand the different types to ensure you choose the best fit. There are many types of AR coatings available, including:
- Single. Single magnesium fluoride coatings have an excellent refractive index for use on glasses, cameras, and other lenses that interact with visible light. The coating can also resist abrasion and humidity.
- Multi. Multi coatings consist of several thin films, each of which has different refraction indices. This type of AR coating maximizes transmission.
- Broadband. Broadband coatings are specifically designed to improve transmission over a wider waveband. As a result, this type of coating is much more versatile.
- “V”. V coatings specifically target a narrow wavelength range, and they are typically used in laser systems. The coating has a high refractive index for all wavelengths outside the designated range.
To learn even more about AR coating considerations, download our eBook, called Key Principles & Design Considerations for Anti-Reflection Coatings, which expands on this information and more.
AR Coatings From Evaporated Coatings
There are many factors to consider when determining whether an AR coating is right for your needs. At Evaporated Coatings, we work with you to identify and design high-quality AR coatings catered to your specific application. Learn more about our anti-reflective coatings or request a quote today to start your order.