Surgical microscope with an interference filter and interference filter

摘要

An interference filter has a 8-12 nm thick interference layer of yttrium fluoride, thorium fluoride, lanthanum fluoride or cerium fluoride applied directly onto a support substrate. Also claimed is an operating microscope (19) which includes the above interference filter (3) located in the beam (9) of an illumination device (21). Preferably, the interference filter has a sequence of ≥ 18 alternating layers of yttrium fluoride, thorium fluoride, lanthanum fluoride or cerium fluoride and of zinc sulphide.