The lens layer itself is clear less. The purpose of the coating is to reduce the reflection of light. But because it is impossible to achieve no reflection at all, there is always residual reflection on the surface of the lens to form a visible color. The color of the lens layer is determined by the thickness of the film, the order of the coating, and the coating time.
Some people ask which of these residual colors is the best. In fact, there is no standard, mainly based on personal preference for color. Currently, there are more greens on the market. However, through these residual colors, we can initially help us to judge the thickness of the film: when the film is thin (thickness ≤ 139nm), the reflected light will appear pale yellowish green, and if the film is thick (thickness ≥ 139nm), it will appear blue-green. The current multilayer anti-reflection film thickness is about 0.3 μm.
It should be noted that the thickness of the film layer is not the only criterion for determining the transmittance or quality of the lens, but is related to the comprehensive factors such as materials and processes.