When light comes into contact with an optical material it is transmitted, reflected and absorbed in varying proportions. The aim of an anti-reflective (AR) coating is to minimise the reflection element and in doing so greatly increase transmission. This is key in applications where high transmission is desirable or where reflection needs to be reduced to prevent stray light affecting other elements of an optical system. Anti-reflective coatings are relatively soft and not suitable for applications where they will be exposed to harsh conditions. Where necessary, tougher AR coatings in the form of diamond-like carbon (DLC) are available.
The most basic form of AR coating is created by using a thin film of single wave material with a refractive index equal to the square root of the substrate’s. This works by creating a second interface and the effect of this is to produce two reflected waves instead of one. If these waves are out of phase they totally or partially cancel the reflected light. Two reflected waves of the same wavelength, 180 degrees out of phase, will produce no reflection. This is known as destructive interference.
AR coatings can be improved by adding further layers with alternating refractive indices, especially if reflection needs to be reduced over a broader band. Single layer AR coatings are designed to function at isolated wavelengths whereas a multi-layer coating is more effective over the broader spectrum.
Knight Optical supply high quality antireflective coatings to your exact specification. Every coating is individually tested by our highly skilled technicians in our state of art metrology lab using our Agilent UMA spectral analysis devise to ensure all components meet our high quality standards.
Knight Optical can supply a range of anti-reflective coatings both single and multi-layer to suit any application. Contact our multilingual technical sales team and discover how Knight Optical’s high quality anti-reflective coatings and service can improve your instrumentation and supply chain experience.
For more information or to place an order contact our multilingual technical sales team on +44 (0)1622 859 444 or email us and discover how Knight Optical can improve your instrumentation and supply chain experience.