Product Description
►Introduction of Reflection Coatings
The optical reflective film reduces the transmittance of light through the characteristics of the materials of dielectric films and metal films. It changes the optical effect of the optical elements.
RZ Optics Co., Ltd. provides custom optical coatings that meet the applications of customers. Our company provides reflection coatings, including dielectric coating, gold coating, silver coating and aluminium coating. Our company specializes in optical coatings for laser optics and optical instruments, for example, high-power lasers, medical imaging systems, camera lenses and infrared optics. Optical components with optical coatings are more widely used.
Reflection coatings are a type of optical coating used to specifically alter the transmission and reflection of light. The change can be particular to a certain wavelength and angle of incidence, allowing some optical elements to be used more efficiently in projects such as optics, imaging and projection.
Reflection coatings were pioneered by chemists in the 1930s and are made using a range of materials such as metals, metallic compounds, and organics for example; oxides, nitrides or fluoride oxides. The layers in a reflection coating are either partially or entirely reflective, with different combinations resulting in alternate transmittance and reflectance. When light is scattered by a surface, a reflection coating reduces the amount of scattered light, allowing more light to efficiently pass through an element, such as a camera lens or eyeglasses.
The combination of coatings used, can affect the angle of incidence and wavelength that the coating is most effective at. For example a single layer of magenta dichroic material reflects light differently to blue light than to red light. Equally, the angle of incidence for surfaces on the element can ultimately affect the amount of reflectance or transmittance the reflection coating can have. This can be calculated through a process known as ray tracing. Traditionally, single layer coatings are most effective at a single wavelength and angle of incidence. In order to utilise a coating for a wider range of angles and wavelengths, multi-layer coatings can be used. These layers are often extremely thin and can be stacked on top of one another to create wider angles and wavelength of transmittance and reflectance.
In the same way the types of materials used in the coating process can change, so too can the coating procedure. Vacuum deposition methods are used in order to coat small to large objects and mirror coatings. In this procedure, the material is heated up and placed in a vacuumed chamber, during which electrons bombard the particles and bond it to the object. Physical and chemical vapour deposition is another popular method used. Generally this is used to coat smaller magnification elements such as spectacle lenses.
Dielectric Coatings
The high-reflective all-dielectric coating is composed of dielectric materials with basically different refractive indexes, which improve the reflection effect of optical surfaces through the reflection and interference of multiple optical interfaces. The high-reflective all-dielectric coating accurately and effectively separates the ultraviolet, visible and infrared spectrum. It optimizes its optical effects for specific wavelength bands. High-reflection all-dielectric coatings are often used for high-reflection laser mirrors, filters and other optical components.
Metallic Coatings
The metal film uses the optical properties of the metal to increase the reflectivity of the surface of optical elements.
Gold coating is often used in infrared spectroscopy above 700nm. Due to the low hardness of gold, a dielectric film or other protective film needs to be coated on its surface to extend its service life. Gold coating is often used as a protective film for low-power laser mirrors, infrared mirrors for measurement and optical components.
Silver coating has a high reflectivity in the visible and infrared spectrum. Since the oxide film formed by silver and air is not enough to ensure the service life of the silver film. A dielectric film or other protective film needs to be coated on the silver film. The silver film is used for low-power laser mirrors and optical mirrors in astronomical measuring instruments.
Aluminium coating has good reflectivity in the ultraviolet, visible and infrared spectrum ranges. Since aluminium has a wide transmission range and is easy to vaporize. Aluminium film has become a widely used metal thin film. Aluminium film is used for optical mirrors required for measurement and astronomical observation.
►Application of Reflection Coatings
For spectacle lenses and camera lenses, various types of reflection coating can be used to manipulate the light they receive. When compared to single coated lenses, multi-layered lenses offer both anti-reflective and reflective benefits due to casing interference effects produced within their structure. Anti-reflective lenses are primarily used to reduce ghost reflection and increase light transmission, affecting the sharpness of the lenses. Mirror coatings or enhanced reflection lenses on the other hand, have a highly reflective surface designed to provide protection from UV radiation and reduce lower amounts of scattered light for clearer vision.
Overall, the benefit of reflection coating on camera lens and eyeglasses is both in terms of aesthetics and practicality. As optical elements are exposed to a variety of light sources, reflection coating offers protection and better viewing experiences. This type of coating manipulation is also used in projectors and lens design, such as beam-splitting. Reflection coating technology is constantly improving in terms of material composition and deposition methods, enabling products to remain highly efficient despite lightweight frames.
