01/10/2026
Why does one AR coating reflect green, while another appears blue or violet? 🔍
It is not accidental.
An anti-reflective coating reduces most of the light reflected from the lens surface, but a small amount of reflection still remains. This is what we see as the characteristic green, blue or violet hue on the lens.
As our Lead Coating Technologist, Irmantas Janulis, explains:
“Visible light contains the entire spectrum of colours – almost like a rainbow. When designing a coating, we can influence which colour becomes more visible in the residual reflection. That is why some coatings appear green, while others look blue or violet.”
However, achieving the desired reflection colour is only one part of the process.
The greater challenge is ensuring that the same shade can be reproduced consistently from one production batch to the next.
The final result can be influenced by many details – the condition and preparation of the equipment, cleanliness inside the vacuum system and precisely controlled process parameters.
Even small differences can affect the final appearance.
Irmantas adds:
“Even details such as how the equipment was cleaned or prepared can influence the final result. That is why we regularly maintain the equipment, keep the system clean and monitor the key machine parameters throughout the entire process.”
This is why proven, consistently reproducible reflection shades are so important in production.
For example, our Blue coating has a characteristic bluish residual reflection while also helping protect against UV and part of the blue-light spectrum.
Similar functional properties can be combined with greenish, yellowish or even reddish reflection shades – but achieving the exact desired colour and reproducing it consistently becomes technically more demanding.
So when you notice a subtle colour reflected from a lens, you are seeing more than just an aesthetic characteristic.
It is the result of light interference, coating design and a precisely controlled manufacturing process – all working together at a microscopic scale.
Because in AR coatings, even the colour of the reflection is engineered.