When you are choosing the type of laser window to use, you should take into consideration that Coated laser windows protects the system and the staff operating the system, therefore you should be opting for a high-quality and affordable solution for the optics of your lasers. This laser window comes with anti-reflective special glass that acts as a protective shield in front of the optics. This comes in various glass thicknesses, diameters, or wavelengths. The single surface coated laser windows with a choice of antireflection coating come with a <10 arcsec or 30 arcmin wedge. User-specified AR-coated laser windows are precisely polished before a high-power, the low-loss dielectric antireflection coating is applied to one side. AR coating wavelength, angle of incidence, and polarization may be specified for optimum performance. The anti-reflective coating enhances performance. The laser beam of light generates a back reflection during the transition from one into another medium. Antireflective coatings are used to minimize effects like loss of power and the appearance of dangerous hot spots caused by the back reflection. Antireflective coatings are used in a variety of optics as they reduce the reflection of glass surfaces. The increased light transmission and a reduction of aberrations are the main advantages. In other to obtain optimum performance, the required wavelength range should be taken into consideration, the substrate material should either be fused Silica, BK7, Borosilicate glass 3.3, Float glass, Sapphire, and more. Their dimension tolerances should be known, transmission output and reflection, angle of incidence in degrees, laser power density in W/cm² (CW), and the energy density in J/cm² (pulsed laser).
Surface Coating For Laser Coating
Anti-reflections Coating
The anti-reflection coating can either be in form of a single layer coating, which Reduces Fresnel reflection of the substrate such as fused silica from approximately 4% to 1.5% per surface, or used in commercial optical products and less demanding applications. The broadband coating has a multi-layer coating consisting of layers of different refractive indices, providing reflectivity of less than 0.3% per surface, over a wide wavelength range as compared to single-layer AR coating and also used in multi-wavelength laser, optical custom lenses, and display windows. The third option here is the V-coating which is optimized for low reflection, with surface reflectance of less than 0.25% at one specific wavelength and provides efficient transmittance for complex optical systems. Near-UV coating with high reflectivity of less than 0.5% from 360 – 620nm.
Dielectric High Reflective Coating
This type of coating uses optical interference coatings to change the reflectivity of the optical surfaces and this can be achieved from nearly zero (anti-reflection coatings) to nearly 100% (R > 99.9%), usually at a specific wavelength or wavelength range. This type of coating is used in many scientific optical instruments, as well as consumer devices and photographic lenses.
Metallic Mirror Coating
This type of coating is the most common, and most popular type of coating we know, it is cheap, has poor reflectance, mechanical and damage durability than other types of coating. They also vary in types depending on the metal used like protected aluminum coating which provides over 88% average surface reflection in the visible spectrum (400nm – 700nm) and is coated with a layer of the dielectric to provide better resistance to abrasion and oxidation. Enhanced aluminum provides about 93% average surface reflection in the visible spectrum (400nm – 700nm) with high reflectivity and better resistance to abrasion with an overcoat of multilayers dielectric. The silver coating which provides about 97% average surface reflection in the visible spectrum (400nm – 700nm), offers a high reflection of about 96% with a layer of dielectric overcoat. Lastly is the protected gold coating which provides over 98% average surface reflection at a wavelength range of 20nm – 800nm and protects with dielectric layers. At Alpine research optics, their product design and manufacture custom optical filters options are top notch.
Edge Pass Coating
This type of coating is of three types the long wave pass coating, short wave pass coating, and narrowband minus. The long wave pass coating reflects more than 99% of the shorter wavelengths at a wavelength of 400-700nm and transmits 95% longer wavelengths from 780-1200nm with a 50% cut-off wavelength around 750nm. The short wave pass coating reflects longer wavelengths from 500-700nm and transmits shorter wavelengths from 325-450nm with a 50% cut-off wavelength around 470nm. Narrowband Minus has a nominal bandwidth of 110nm with an average reflection of more than 99% over a nominal bandwidth of 30-40 nm and an average transmission of 90%.
