Lanthanum Flint glass
Lanthanum Flint glass is referred to as LaF glass. In the nd-v diagram, it is located above the heavy barium flint glass, and the dispersion is smaller than that of the heavy flint glass. Together with lanthanum crown and heavy lanthanum flint glass, it forms a high-refraction, low-dispersion, colorless optical glass series. LaF glass is made by introducing La2O3, ThO2, CdO, Ta2O5, Nb2O5, etc. on the basis of ZBaF glass, but cadmium raw materials have pollution problems, and thorium has weak radioactivity, so it is no longer used. Mainly used for high-quality photographic objectives.
By modifying the glass formula, the optical glass without lead, arsenic and cadmium and other radioactive elements is expressed by a prefix "H-" indicating its envioronment-friendly characteristics, for example: H-LAF10LA.
