Anti-Reflective Coatings

In order to make glass surfaces less reflective, you can apply a special coating to them, which is known as a λ/4 coating. A common material for this is magnesium fluoride (MgF2). The thickness of this coating should be selected, so that it corresponds to the formula d = λ/(4 x n), where n is the refractive index of the material. This means that the reflected light waves cancel each other out, and the glass reflects less light.

Another method uses three coatings with different refractive indices. This achieves a smooth transition from the refractive index of the air to the refractive index of the glass, which reduces the reflection effect accordingly.

For optimum results, where reflections are almost completely avoided and light transmission is maximized, more complex multi-coating systems are required. These consist of alternating coatings of materials with different refractive indices. The precise thickness of these coatings (and the many transitions between them) influence how the light passes through them and how it is reflected.

Low-refractive dielectrics

1. Magnesium fluorite (MgF2) with n = 1,38
2. Silicon oxide (SiO2) with n = 1,46
3. Aluminium oxide (Al2O3) with n = 1,67

High refractive dielectrics

1. Titanium oxide (TiO2) with n = 2,55
2. Tantalum oxide (Ta2O5) with n = 2,20
3. Zirconium oxide (ZrO2) with n = 2,15
4. Silicon nitride (Si3N4) with n = 2,05