High Crown 1.6-1.9
High power plus lenses made from normal crown glass have larger center thicknesses whereas high power minus lenses have larger edge thicknesses.
To overcome the problems which spectacle wearers may have because of this, a wide range of glass types with high refractive indices and relatively low densities is available. They are suitable for the manufacture of thin and attractive high power lenses which are, in addition, lighter than those lenses made from crown glass.
|D0290||HC-Weiss 0290||clear||Refractive index (n) = 1.6|
|D0786||BS 565||clear||Refractive index (n) = 1.65|
|D0888||BaSF 64||clear||Refractive index (n) = 1.7|
|D0386 1||BS 5675||clear||Refractive index (n) = 1.75|
|D0785||laSF 1.8/35||clear||Refractive index (n) = 1.8|
|D0185||BS 5680||clear||Refractive index (n) = 1.8|
|D0082||laSF 1.9/30||clear||Refractive index (n) = 1.9|