Sigma has filed a patent for the development of a multi-coated lens coatings which will consist of 6 layers of varying refractive indices and provide low reflectivity over a wide range of wavelengths.
Patent details.
1. Layer characteristics
The first layer has a high coefficient of. refractive index of 1.6 to 2.5 and its thickness is from 0.045&lambda up to 0.911&lambda
The second layer has a low coefficient. refractions from 1.3 to 1.5 and its thickness is from 0.025&lambda to 0.166&lambda
The third layer will have a high refractive index. refractive index from 1.6 to 2.5, and its thickness is from 0.038&lambda to 0.375&lambda
The fourth layer has a low coefficient of. refractions from 1.3 to 1.5, and its thickness is from 0.048&lambda up to 0.152&lambda
The fifth layer has a high refractive index. refraction from 1.8 to 2.5, and its thickness is from 0.045&lambda to 0.119&lambda
The sixth layer has a low coefficient of. refraction from 1.1 to 1.3, and its thickness is from, 0.228&lambda to 0.3131&lambda
2. Layer materials
The sixth layer could be made of silicon dioxide, magnesium fluoride, aluminum oxide and optical resin or a mixture of these materials
The first layer, third layer and fifth layer can be made from materials such as cerium oxide, hafnium oxide, indium oxide, niobium oxide, tin oxide, tantalum oxide, titanium oxide, yttrium oxide, zirconium oxide, zinc oxide, praseodymium oxide or mixtures of the above oxides.
Second and fourth layers are made of aluminum oxide, magnesium fluoride, silicon oxide, or a mixture of these oxides.
3. Application methods
First layer, second layer, third layer, fourth layer and fifth layer each use one of the following coating methods: vacuum deposition, vapor deposition, CVD or ALD
The sixth layer is formed by wet application
What are the key benefits of Sigma’s new lens coatings and how do they improve the overall image quality and performance of their lenses compared to previous models?