The U.S. Army Corps of Engineers is organized geographically into eight permanent divisions, one provisional division, one provisional district, and one research command reporting directly to the HQ. Within each division, there are several districts.
Laser Safety Glasses - Holmium Laser. 1  On this page you will find our range of Holmium laser safety glasses , Ruby laser safety glasses, Dye and Erbium Laser Safety Glasses. 2  Important: Australian laser safety standards AS/NZS 2211.3:2002 require L-Ratings to be clearly marked on the laser glasses.
Part of the lanthanide series, holmium is a rare earth element. Holmium was discovered by Swedish chemist Per Theodor Cleve. Its oxide was first isolated from rare earth ores in 1878 and the element was named after the city of Stockholm. Elemental holmium is a relatively soft and malleable silvery-white metal. It is too reactive to be found uncombined in nature, but when isolated, is relatively stable in dry air at room temperature.