Optical quality mirrors are not your everyday mirror design and are dependent upon the final application, the desired quality, and of course, your project budget. Mirror designs are available as standard off-the-shelf products or as highly custom for material thickness, diameter, and reflection performance. High-reflector coatings which are capable of 99.0% or more are typically used in laser systems as there is very little light lost. The vast global demand for optical mirror coatings used in military, consumer, and medical markets continues to grow every year.
Are you interested in learning more about Aluminum coated mirrors? Contact us today to secure an expert consultation!
Aluminum-coated mirrors
Enhanced aluminum coatings, including a dielectric overcoat, typically reflect 92-95% of the visible light spectrum and are the most common coating for optical mirror production. Thin layers of aluminum are applied to create a flat and highly reflective surface. Protected aluminum coatings may contain a single layer dielectric overcoat and typically reflect 90-92% in the visible region.
Silver vs. aluminum optical coatings
Sometimes referred to as metalized platings, the end-use determines whether silver or aluminum coatings are required. Your application will determine the reflectivity requirement as well as the emissivity (the energy radiated from the surface of the mirror).
Aluminum is highly desirable for UV applications when used as a single mirror source. Its high reflectance properties for UV and IR make it a clear choice for telescopes, life science, research, and defense applications.
Silver mirrors, on the other hand, perform better overall in the visible band, as it is the most reflective surface until the light source falls into the UV at 400 µm. Unless protected, bare silver will tarnish over time, which is undesirable as it degrades the mirror&#;s performance. Observatory telescopes have shown improved performance by changing from aluminum mirrors to silver-coated mirrors. Silver offers less reliability when adhering to glass materials and is more suited for coating metal substrates.
Defending your optic - Protected vs. non-protected coatings
Typically for higher durability, the harder metals such as aluminum coatings fare better. To determine if a protective layer is required, you must consider environmental factors like heat, salt, or humidity. Commonly, MIL-Spec testing and specifications need to be met for specific use cases, even if not a military application. All metal mirror coatings are quite thin and can be easily scratched if not handled carefully or cleaned too aggressively. A protective layer is added to a softer metal for increased durability. Typically, this layer is made of SiO for a visible wavelength mirror and is harder than the coating layer of gold, silver, or aluminum.
Get best-in-class IR with gold coatings. Protected gold polygons and spinners for today&#;s laser scanning technology, including LiDAR, for use in the IR wavelength range, are a common mirror coating request at AccuCoat. A dielectric overcoating may also be added at the end of the layering process to create a protective barrier to keep the optic clean and less prone to scratching. With a high average reflectance (97-99%), protected gold coatings offer higher performance and are the preferred option when mitigating loss from the light source.
Tips on Ordering Mirror Coatings. The initial questions when you are looking to create a mirror surface optic can be daunting. AccuCoat has given the first time optical mirror buyer a solid ground to start with by using our checklist developed for this purpose, Top Specs for Coatings on Metals.
Items to consider include:
For additional substrates tips, see our other checklists for RFQs on glass and plastics substrates.
The seasoned technical professionals at AccuCoat are available to walk you through the selection and design of the right coating for your application. We encourage you to contact our experts for support before your next mirror coating project.
Mirror coatings are back in style and becoming increasingly popular every day. Knowing how to order a mirror coat to obtain the patient's desires can be challenging, but with these helpful tips and information, this process will become a breeze.
Mirror coatings were released as a functional reflective coating to help redirect sunlight from the surface of lenses. Other than its extreme fashionability, mirror coatings actually help reduce harsh glares when paired with sun wear. A solid mirror coating can block about 10-15% of harsh glares, while a flash mirror can block up to 5-8%. When combined with a polarized lens, your patients will receive the ultimate mirror coating that adds to the comfort of anyone who suffers from outdoor light sensitivity.
A common misconception of mirror coatings is that they can be applied to any lens, regardless of the base color or density. Unfortunately, that is not the case. Mirror coating is similar to AR coating in that it is applied in layers inside an extraordinarily hot chamber. When used on a clear lens, it will give the same effect that an AR coating would give - a little sparkle in the light.
The most common types of mirrors are solid, flash, and gradient. There is also a double gradient option that we won't expand on here due to its lack of customization and availability.
Solid Mirrors
Solid mirrors are the traditional, full-coverage mirror that shows a complete reflection on the lenses. This type of mirror is at its best when paired with a polarized or dark, solid-tinted base. When ordering this lens, you want to make sure the base color will complement the mirror color.
For example, most of the warm mirrors will want to be paired with a brown base. These colors can include gold, red, or even rose gold. In turn, you will always pair your cool colors with a gray base. These colors would include blue, green, or silver.
The quickest and most consistent option for a solid mirror would be the KBCO Pre-Mirrored polarized lens option. These lens blanks are designed with the solid mirror already applied to the lens blank before it is surfaced. Available in over a dozen colors in poly and 1.67 material. This product allows consistent colors over time allowing for multi-pair sales and one-lens remakes that are going to match.
Flash Mirrors
Like solid mirrors, the flash mirror will also cover the full surface of the lens. However, it is considered a "half mirror" or "fashion mirror" in which you will still be able to see your eyes through the lenses. This type of mirror can be applied to any base color and density, with the exception of clear.
You can also use this type of mirror on a photochromic lens. When the lens is in its clear state, like an AR coating, it will give off a little sparkle of color until the photochromic is fully activated. This is essentially what is done with the Transitions XTRActive Style Mirrors.
Gradient Mirrors
Gradient mirror coatings are the densest at the top of the lens and fade to nothing on the bottom. This type of mirror is best for overhead sunlight and allows more light to pass through the middle and lower parts of the lens. This mirror is best for drivers, cyclists, and people who enjoy reading outdoors.
This option is also available on any base density, with the exception of clear. There is a bit more customization that can be done with this option in the sense that you can pair it with a solid base or even a gradient base that will pair nicely with the gradient mirror.
If you are looking for more details, kindly visit Sapphire Optical Components China.
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